Keynote/Invited Speakers
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I. Emerging Materials for Rechargeable Batteries
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Keynote Speakers
Yong-Mook Kang
Korea UniversityInnovating layered cathode materials through the mechanistic understanding of its disorders
AbstractInnovating layered cathode materials through the mechanistic understanding of its disorders
Irreversible phase transformations of layered oxide cathodes during charging have been detrimental for most of them. Even if a lot of efforts have been made to relieve this highly irreversible phase transformation, there have been just a few successful results, which definitely limit the amount of extracted alkali ions and thereby the available capacities of the layered oxides. So, this presentation will suggest couple of strategies to get over the saturated cathode technology.
As an inverse conceptual strategy, we first observed the possibility to make this irreversible phase transformation extremely reversible by utilizing crystal water as a pillar. Although we found a few cyrstal structures working with this reversible phase transition, the works using Na-birnessite (NaxMnO2•yH2O; Na-bir) or Li-birnessite (Li-bir) as basic structural units will be highlighted here. The crystal water in the structure contributes to generating metastable spinel-like phase, which is the key factor for making this unusual reversibility happen. The reversible structural rearrangement between layered and spinel-like phases during electrochemical reaction can activate new cation sites and enhance ion diffusion with higher structural stability. This unprecedented reversible phase transformation between spinel and layered structure is affected by the steric coordination or amount of crystal water in the lattice as well as the low crystallinity of pristine layered materials. Hence, this research may be correlated with the mechanism behind DRX(disordered rocksalt) cathodes. Pseudo Jahn-Teller effect (Pseudo JTE) will be also stressed out as a fundamental reason behind lattice distortion of layered oxide cathodes. Even though Jahn-Teller effect (JTE) has been regarded as one of the most important determinators of how much stress layered cathode materials undergo during charge and discharge, there have been many reports that traces of superstructure exist in pristine layered materials and irreversible phase transitions occur even after eliminating the JTE. A careful consideration of the energy of cationic distortion using a Taylor expansion indicated that second-order JTE (Pseudo JTE) is more widespread than the aforementioned JTE because of the various bonding states that occur between bonding and anti-bonding molecular orbitals in transition metal octahedra. As a model case, some of layered oxide cathodes will be dealt with in this presentation. In order to manipulate more Li from layered cathodes, oxygen redox should be stabilized because the capacity from cationic redox has been already saturated. Herein, by investigating more fundamental reasons for oxygen redox which can be valid for not only Li-rich layered cathodes but also conventional ones with rhombohedral symmetry, we will suggest the realistic solution to stabilize oxygen redox toward higher energy density and safety.
The aforementioned strategies will provide deep insight into novel class of intercalating materials, and thus it can break up some typical prejudices which we have about the layered cathodes for alkali ion (Li or Na) secondary batteries.CV
Jinhyuk Lee
McGill UniversityAdvancing high-energy and cost-efficient Ni- and Co-free Li-ion batteries through disordered rock-salt cathode materials
AbstractAdvancing high-energy and cost-efficient Ni- and Co-free Li-ion batteries through disordered rock-salt cathode materials
The global transition towards electric vehicles and large-scale energy storage systems demands cost-effective and abundant alternatives to conventional Co/Ni-based cathodes, exemplified by materials like LiNi0.6Mn0.2Co0.2O2, for lithium-ion batteries (LIBs). Disordered rock-salt (DRX) cathode materials, such as Li1.2Mn0.4Ti0.4O2 and Li2Mn0.5Ti0.5O2F, have emerged as promising candidates due to their potential to utilize earth-abundant metals like Mn, Fe, and Ti, alongside their impressive energy density exceeding 900 Wh/kg. However, significant challenges persist before these materials can be practically integrated into LIBs. In this presentation, I will explore the current understanding, obstacles, and opportunities associated with developing Ni- and Co-free LIBs using DRX cathode materials.
CV
Jongwoo Lim
Seoul National UniversityHow interfaces control lithium (de)insertion pathway: Comparing liquid and solid electrolytes
AbstractHow interfaces control lithium (de)insertion pathway: Comparing liquid and solid electrolytes
In the realm of lithium-ion batteries, the process of lithium (de)insertion follows a two-fold pathway, encompassing (1) charge transfer occurring at the electrolyte-electrode interface and (2) solid-state lithium diffusion within electrode. Conventionally, these two transport mechanisms have been regarded as distinct and investigated separately due to their sequential occurrence during battery cycling. However, our recent research demonstrates that the kinetics of charge transfer can excert control over the spatial distribution of lithium on the surface, consequently influencing the entire lithium (de)insertion pathway.
In addition, in the field of all-solid-state batteries (ASSBs), the interface between solid-electrolytes and electrodes further modulates the surface charge transfer kinetics, active surface areas, and local stresses. Chemo-mechanical properties in ASSBs complicate interfacial charge transfer and further affect lithium diffusion within the electrodes. In this talk, I will present how our synchrotron-based operando X-ray diffraction and imaging could help understand such phenomena.CVInvited Speakers
Name Affiliation Title Abstract CV Hongkyung Lee DGIST Interface Matter: Uniformly Regulating Interfacial Evolution across Lithium Metal Batteries AbstractInterface Matter: Uniformly Regulating Interfacial Evolution across Lithium Metal Batteries
Inhibiting dendritic lithium (Li) plating has long been highly desired for building safe and reliable Li-metal batteries (LMBs). However, suppressing Li dendrite growth has long been challenging through conventional materials and cell platforms and their design principles that could not satisfy the demands of fast, uniform ionic transport and interphase reinforcement. Notably, the dendrite-triggered, chaotic evolution of Li-electrolyte interfaces is uncontrollable upon prolonged cycling of practical LMBs. This presentation will present novel approaches to ensure the spatial and temporal uniformity of the Li-electrolyte interfaces across LMBs through the new electrolyte designs and tailoring of the original surfaces of starting Li-metal anodes. Before moving on to the main parts, this talk will study the Li dendrite-triggered failure scenario and the dynamic structural and chemical evolution of Li-electrolyte interfaces in the cycling of LMBs under stringent conditions and update the status and worldwide efforts in LMB technology. To regulate the Li+ transport across the electrolytes, I will discuss the Li+ flux redistributing strategy with nanospinbar-assisted dynamic Li+ transfer over the Li-metal surface. After addressing the inherently uneven nature of the native layer of commercial Li, I will propose some strategies to reconstruct the Li-metal surface for reducing the surface reactivity and improving the surface homogeneity by revisiting the electrodeposition of large-area, ultrathin Li-metal. Moving apart from the traditional interfacial roles in the current Li-ion battery platform, our preliminaries presented in this talk highlight the urgent need for intelligent battery interface design to adapt to the dynamic changes of Li-electrolyte interfaces across large-area, high-energy LMBs.
CVKeun Hyung Lee Inha University 3D Interconnected Polymer Networks for Energy Storage Applications Abstract3D Interconnected Polymer Networks for Energy Storage Applications
The rapid advancement of portable, lightweight, and flexible/wearable electronics has spurred significant research into solid-state deformable energy storage devices. Such devices can be realized through either modifying the geometrical structures of active components or utilizing inherently flexible/deformable polymer materials. Structural alterations, including buckling, the incorporation of rigid islands/elastic bridges, helically coiled springs, and the creation of 2D/3D porous structures, necessitate precise geometrical design and complex multistep fabrication processes. Conversely, inherently deformable active components can be achieved by blending rigid active materials into rubbery composites capable of accommodating strain, and by incorporating 1D nanomaterials with substantial aspect ratios, such as nanowires and nanofibers, to maintain electrical contact during mechanical deformation. Intrinsic deformable components offer versatility, particularly due to their compatibility with conventional layer-stacking processes, enabling cost-effective and large-scale fabrication. This presentation discusses various strategies for developing flexible and stretchable solid polymer electrolytes and electrodes incorporating 3D interconnected rubbery networks. These materials were successfully utilized in deformable supercapacitors and batteries.
CVSung-Kyun Jung UNIST Guided phase transition in host formation reaction for designing cathode materials of Li-ion batteries AbstractGuided phase transition in host formation reaction for designing cathode materials of Li-ion batteries
Attempts to explore materials that store lithium ions and electrons separately open a new branch of cathode materials and design strategy through numerous combinations of lithium compounds and transition metal compounds. Among the combination, host formation reaction transforming the transition metal compounds to reversible host for lithium ion storage with incorporation of anion from electrochemical splitting of lithium compounds enables to excavate the new polymorph of cathode materials. Here, we introduce the guided phase transition mechanism of host formation reaction inducing the phase transformation of transition metal compounds to new metastable phase analogous to original crystal structure. In LiF-FeF2 composite model system, the crystal structure of tetragonal FeF2 successfully guide phase transition route to reach metastable tetragonal FeF3 contrary to the formation of thermodynamically stable rhombohedral FeF3. Resemblance of crystal structure between tetragonal FeF2 and FeF3 alleviates compositional inhomogeneity even in intercalation and conversion reaction resulting low voltage hysteresis and high reversibility. We believe that guiding the reaction pathway to minimize the change in crystal structure in intercalation and conversion reaction is essence to evade irreversible reaction pathway for conversion cathode materials.
CVDong-Joo Yoo Korea University Development of Intimate Contact Technology for High Performance All-Solid-State Batteries AbstractDevelopment of Intimate Contact Technology for High Performance All-Solid-State Batteries
The widespread adoption of electric vehicles (EVs) as alternatives to fossil fuels to facilitate a greener and more sustainable future is the most remarkable technological development of recent years. Nevertheless, the exponential increase in energy demand has given rise to significant concerns regarding the safety of batteries, which necessitates urgent consideration. While conventional lithium-ion batteries (LIBs) employ flammable liquid electrolytes, they have demonstrated susceptibility to thermal runaway incidents, which present significant safety hazards and necessitate a fundamental transformation in energy storage technologies. All-solid-state batteries (ASSBs) have emerged as a promising alternative that is able to revolutionize the energy storage industry.
One of the primary obstacles that greatly hampers the performance of ASSBs is the issue of point contact between the solid electrolytes and the active materials. This problem stems from poor interfacial adhesion and restricted intimate contact between the two components, impeding effective charge transfer and ion diffusion. The presence of non-conductive interfaces, voids, or delamination zones hinders the efficient diffusion of lithium ions, resulting in increased interfacial resistance and restricted usage of active materials within the electrodes. Furthermore, the issue of solid contact contributes to the localized stress concentration and mechanical strain that occurs during charge-discharge cycles. In this presentation, the concepts of intimate contact in both the anode and cathode will be discussed.CVJungjin Park KIST Control particle ensembles in Li intercalation layered oxides: Autocatalysis and Autoinhibition AbstractControl particle ensembles in Li intercalation layered oxides: Autocatalysis and Autoinhibition
Layered oxides widely used as lithium-ion battery electrodes are designed to be cycled under conditions that avoid phase transitions. Although the desired single-phase composition ranges are well established near equilibrium, operando diffraction studies on many-particle porous electrodes have suggested phase separation during delithiation. Notably, the separation is not always observed, and never during lithiation. These anomalies have been attributed to irreversible processes during the first delithiation or reversible concentration-dependent diffusion. However, these explanations are not consistent with all experimental observations such as rate and path dependencies and particle-by particle lithium concentration changes.
This presentation, I will show that the apparent phase separation is a dynamical artifact occurring in a many-particle system driven by autocatalytic electrochemical reactions, that is, an interfacial exchange current that increases with the extent of delithiation. I experimentally validate this population-dynamics model using the single-phase material Lix(Ni1/3Mn1/3Co1/3)O2 (0.5 < x < 1) and demonstrate generality with other transition-metal compositions. Operando diffraction and nanoscale oxidation-state mapping unambiguously prove that this fictitious phase separation is a repeatable non-equilibrium effect. I quantitatively confirm the theory with multiple-datastream-driven model extraction. More generally, our study experimentally demonstrates the control of ensemble stability by electro-autocatalysis, highlighting the importance of population dynamics in battery electrodes (even non-phase-separating ones).CVJae Chul Kim Stevens Institute of Technology Electrowritten Fiber-Enhanced Copper Current Collectors for Anode-Free Batteries AbstractElectrowritten Fiber-Enhanced Copper Current Collectors for Anode-Free Batteries
We have developed an electrospinning-based manufacturing process tailored for battery systems that involve metallic lithium. In this presentation, we will present how to achieve precise three-dimensional (3D) geometrical control of fiber construction through an enhanced electrospinning method aiming at obtaining manufacturing precision comparable to 3D printing at a micro-scale. Unlike traditional techniques, our approach employs a mobile stage enabling fiber alignment. The resulting fibrous structures will be utilized in fabricating the anode current collectors for an innovative anode-free battery, a promising alternative to conventional Li-ion batteries. While integrating Li metal has historically posed challenges due to uncontrolled dendrite growth during Li plating and stripping, our research reveals that the 3D fibrous structure reinforced current collector enhances Li storage efficiency over numerous cycles compared to planar counterparts. We will discuss the effect of fiber compositions and controlled geometrical configurations on stabilizing Li plating and stripping morphologies to suppress dendrite growth. Additionally, we will propose a cell design principle to fundamentally extend the cycle life of anode-free batteries. Significantly, we believe that the advancement in battery manufacturing demonstrated in this work offers a systematic approach to developing next-generation energy storage systems, contributing to a sustainable energy future.
CVMinjoon Park Pusan National University Recent Progress in Zinc-Based Aqueous Redox Flow Batteries: Hybrid design, Membrane-free, Cathode recycling AbstractRecent Progress in Zinc-Based Aqueous Redox Flow Batteries: Hybrid design, Membrane-free, Cathode recycling
Conventional Mn-based aqueous zinc-ion battery is highly safe energy storage system, but low operating voltage (<1.5V) and low energy density limits its broad application in large-scale energy storage system. Recently, a novel aqueous zinc-manganese dioxide redox flow battery is reported. This battery is composed of Mn2+ based acidic catholyte and Zn2+ based alkaline anolyte, respectively, exhibiting an open circuit voltage of 2.66 V. Also, a neutral electrolyte was located between two different membranes to prevent the cross contamination of acidic and alkaline electrolytes, maintaining the charge balance. However, Mn3+ ions suffer from the disproportionation side reaction, lowering battery performance. Thus, the low reversibility of Mn/MnO2 redox couple should be improved for broad application of Zn-Mn redox flow batteries. In addition, the formation of zinc dendrite should be suppressed when the zinc-based anolyte was used, which could deteriorate the cell performance.
In this work, we report a high voltage aqueous Zn−Mn hybrid redox flow battery with a high operating voltage of 2.75 V at the 100% state of charge. Also, we show the recycling process of lithium-ion battery’s cathode by using the hybrid redox flow batteries. This work is a significant step forward by exploring the pH differential hybrid flow cell with the double-membrane, three-electrolyte configuration. Finally we introduce the membrane-free Zn-Mn redox flow battery with high stability.
Acknowledgements
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No.2021R1C1C1008349)CVYoungjin Kim Kangwon National University Understanding the Complicated nature of Residual Lithium in High-Nickel Lithium-Ion Battery Cathodes AbstractUnderstanding the Complicated nature of Residual Lithium in High-Nickel Lithium-Ion Battery Cathodes
The adoption of lithium-ion batteries (LIBs) by the electric vehicle (EV) industry highlights the necessity for advancements in high-energy density and cost-efficiency. Cathode materials with high nickel content, also known as high-Ni materials, are notable for their capacity to enhance energy storage. However, they encounter difficulties due to the presence of residual lithium compounds such as LiOH and Li2CO3. These substances not only induce the release of gas, thereby posing a potential threat to the integrity of the battery, but also interfere with the slurry coating procedure by forming gel-like aggregates as a result of interactions with the polyvinylidene fluoride (PVdF) binder. Although the advantages of dry coating for high-Ni cathodes are acknowledged, there is still limited research on the processes of lithium compound formation/removal, Li+/H+ exchanges, and the influence of lithium source impurities.
This study looks into the issues raised above by using a new titration method and studying the structure of the material before and after cobalt hydroxide was added. The objective is to elucidate the behavior of lithium residues on cathodes with high nickel content. Our research aims to address the challenges posed by high-Ni oxide by focusing on the development of cathode materials to improve the performance of LIBs in EVs. This study not only identifies key factors that influence the presence of lithium compounds but also provides valuable insights into strategies for mitigating their negative effects. This research represents a significant advancement towards the development of optimized cathode materials with high nickel content for potential commercial applications in the future.CV
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II. Materials and Devices for Displays and Optoelectronics
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Keynote Speakers
Wallace Choy
The University of Hong KongNano-perovskite materials for high performance light-emitting diodes and photodetectors
AbstractNano-perovskite materials for high performance light-emitting diodes and photodetectors
Halide perovskites have raised wide interest these years for photovoltaics, light-emitting diodes, and other applications due to their excellent optical and electronic properties, low cost, solution processability, and diversity as a group of materials. By ligand designs, we will discuss the influences on the phase distribution, carrier transfer and confinement of low dimensional perovskites will be improved. Using blue quasi-2D perovskites LEDs as examples, we can enhance the hole injection for better balance carrier and improve the efficiency[1], we also modulate the n-phase distribution[2,3] and optimize the carrier transfer and confinement to improve the performances of PeLEDs[4]. For perovskite nanocrystals (NCs), we will introduce new ligands to synthesized red color perovskite (CsPbI3) NCs. The ligand can significantly stabilize the CsPbI3 NCs without any crystalline deformation on the NC crystal structure. Additionally, these chemically crosslinked PMA also significantly reduces PbCs deep defects[5]. Overall, the efficiency and stability of the red perovskite LEDs can be significantly improved.
We will also demonstrate new approaches of double-side crystallization and passivation on MA-free Sn-Pb perovskites for UV-NIR photodetection applications[6-8]. The photovoltaic-mode photodetectors show a high and flat efficiency of ~80% at 760-900 nm, a high responsivity of 0.53 A/W, and a high specific detectivity of 6 exp12 Jones at 940 nm. The high-quality Sn-Pb perovskite can be fabricated on metal/Si substrates for promoting direct integration with CMOS electronics and realizing an efficient imaging array [9]. The work contributes to the evolution of perovskite for practical applications in optoelectronic devices.CV
Kazuhiro Ohkawa
KAUSTMaterials and Devices for Displays and Optoelectronics
AbstractMaterials and Devices for Displays and Optoelectronics
Micro-LED displays are energy-saving and fitting for AR and VR applications. InGaN-based RGB micro-LEDs for the pixel of the micro-LED displays will be the breakthrough of cost-competitive micro-LED displays.
InGaN-based blue and green LEDs are bright and very efficient. On the other hand, InGaN-based red LEDs are difficult compared to those LEDs. Therefore, the development of high-quality and high-In-content InGaN is a highly attractive topic for future displays. The difficulty of red emission in InGaN originates from the low-temperature growth of InGaN and strong strain in InGaN/GaN QW structures.
Our original MOVPE and strain-compensation technology are countermeasures for those issues, resulting in highly efficient InGaN-based red LEDs. The typical values of red LEDs are the peak wavelength 630 nm, FWHM 50 nm, EQE 6%, and WPE 3% at 20 mA (<3 V). Since InGaN red LEDs have large conduction offsets in the quantum wells, the characteristic temperature was as high as 400 K at the temperature range of 300-370 K. Also, red 5x5 um2 micro-LEDs have achieved the highest output power density of ca. 1000 mW/cm2 with a peak wavelength of 630 nm at around 100 A/cm2. This result implies the possibility of red and yellow VCSELs based on InGaN.
Recently, we have demonstrated InGaN-based integrated RGB micro-LEDs. Red, green, and blue LEDs are connected with GaN tunnel junctions. The RGB devices have covered 71% of Rec. 2020. The paper will present the recent progress of InGaN LED technologies including the above topics.CVInvited Speakers
Name Affiliation Title Abstract CV Sergey Makarov Harbin Engineering University Perovskite Nanocrystal Lasers AbstractPerovskite Nanocrystal Lasers
Recently, the study of halide perovskites has attracted enormous attention due to their exceptional optical and electrical properties. As a result, this family of materials can provide a prospective platform for modern nanophotonics [1] and metaphotonics [2,3], allowing us to overcome many obstacles associated with the use of conventional semiconductor materials. Resonant halide perovskite micro- and nanocrystals is a rapidly developing research area driven by its potential applications for lasers, nanophotonics, and optoelectronic devices.
Here, we overview the recent progress in the field of halide perovskite lasers starting from record-small plasmon-free single-particle lasers [4] to the larger designs where the perovskite microlasers [5, 6] are coupled with waveguiding systems [7,8,9]. Finally, we report new results on halide perovskite nanolasers based on exciton-polariton condensation and mirror-image Mie modes at a visible wavelength of approximately 0.53 µm with an ultra-small nanocavity volume (λ3/20) [10]. Additional opportunities for lead-free and up-conversion small perovskite lasers is discussed as well.
REFERENCES
S. Makarov, et al. Advanced Optical Materials, 7, 1800784 (2019).
A.S. Berestennikov, et. al. Applied Physics Reviews, 6, 031307 (2019).
P. Tonkaev, et al. Chemical Reviews 122(19), 15414-15449 (2022).
E. Tiguntseva, et al. ACS Nano 13, 4140-4147 (2020).
D.I. Markina, et al. ACS Nano 17, 2, 1570–1582 (2023).
M.A. Masharin, et al. Advanced Functional Materials (2023). arXiv:2212.13042
P. Trofimov, et al. ACS Nano 14, 8126-8134 (2020).
K.R. Safronov, et al. Laser & Photonics Reviews 2100728 (2022).
A. Berestennikov et al. ACS Nano 17, 5, 4445–4452 (2023)
Masharin, M.A., et al Opto-Electronic Advances 7, 230148, (2024).CVHao Zhang Tsinghua University 3D printing of inorganic nanomaterials by photochemically bonding colloidal nanocrystals Abstract3D printing of inorganic nanomaterials by photochemically bonding colloidal nanocrystals
3D printing has been a transformative technology for building porotypes and various functional devices. However, from the materials perspective, direct 3D printing is typically restricted to metals and photocurable polymers. Important inorganic materials, especially the semiconductors and metal oxides, can only be printed with nanoscale resolution in the presence of polymeric or other matrices. The material limitation stems from incompatibility of conditions required for forming atomic bonds in these inorganic materials and the conditions used in regular 3D printing apparatus. To address this issue, we develop an approach for 3D printing of inorganic nanomaterials, or abbreviated as 3D Pin. 3D Pin uses 1) preformed, colloidal inorganic nanocrystals with various compositions as “artificial atoms” or building blocks, and 2) the photochemically bonding between nanocrystals via their native ligands with bisazide linkers. The broad library of colloidal nanocrystals and the nonspecific bonding chemistry of these nanocrystals render 3D Pin universal, as exemplified by over 10 semiconductors (II‒VI, InP, CsPbBr3), metals (Au), metal oxides (In2O3, TiO2), and their mixtures. The printing process, triggered photochemically in the solution of nanocrystals with a femtosecond laser, allows for the formation of 3D objects in arbitrary forms and with nanoscale resolution (~150 nm). The printed structures show high materials purity (inorganic mass fraction over 90%), low porosity, and high mechanical strength. These features also allow the printed structures to preserve the original optical properties of the nanocrystal building blocks and show emergent behaviors, such as chiroptical response, owing to the structural designs. We expect 3D Pin to expand the material library of 3D printing techniques and unlock the designer space for combining inorganic material‒structure for emergent applications.
CVJeonghun Kwak Seoul National University Interface Engineering for High-Performance Quantum Dot Light-Emitting Diodes AbstractInterface Engineering for High-Performance Quantum Dot Light-Emitting Diodes
Colloidal quantum dot (QD) nanocrystals are well-known for their unique optical and electronic properties based on quantum confinement effects. These properties can be precisely tuned through solution-based synthesis by adjusting the size, shape, and chemical composition of the QDs. Due to their adaptability and tunability, QDs have attracted considerable interest in various optoelectronic applications, including QD-based light-emitting diodes (QLEDs), solar cells, photodetectors, and lasers. Among these applications, QLEDs have been of great interest for their potential in the next generation of display devices, as they exhibit exceptional optoelectronic properties. However, to expedite commercialization, it is essential to continuously improve the performance and stability of the devices. Achieving these improvements requires a comprehensive consideration of various factors, ranging from material properties to device architectures. This presentation outlines our recent strategies to improve QLED performance through interface engineering in both QDs and QLEDs. By focusing on these critical aspects, we aim to improve the functionality and efficiency of QLED technology.
CVTae-Hee Han Hanyang University Surface-tailored Perovskite Light Emitters for Optoelectronic Devices AbstractSurface-tailored Perovskite Light Emitters for Optoelectronic Devices
Metal halide perovskites have emerged as a promising candidate for optoelectronic devices, such as solar cells and light-emitting diodes. However, the polycrystalline nature of solution-processed metal halide perovskite films introduces numerous grain boundaries characterized by structural disorders and traps. These defects significantly affect the optoelectronic properties and stability of perovskite thin films and devices. This study presents effective strategies for surface engineering and grain boundary modification in polycrystalline perovskite thin films through precise control of crystal nucleation and growth during solution processing. Successful mitigation of these defects leads to a notable reduction in charged trap densities, enhanced environmental stability, and minimized ion migration within the perovskite thin film. Consequently, significant improvements in the operational stability of optoelectronic devices are achieved, highlighting the critical role of crystal nucleation and growth control in optimizing the performance of metal halide perovskite-based optoelectronics.
CVKeehoon Kang Seoul National University Overcoming Doping Challenges in Metal-Halide Perovskites AbstractOvercoming Doping Challenges in Metal-Halide Perovskites
Doping has been one of the most essential methods to control charge carrier concentration in semiconductors. In metal halide perovskite (MHP), which have revolutionized the field of solar cells and light-emitting diodes due to their favorable optoelectrical properties, extensive electrical doping via conventional substitutional doping still remains challenging due to their structural stability limited by tolerance factor and compensation of intentionally introduced defects by mobile halide ions[1]. As an alternative non-invasive approach, molecular doping has been previously reported for tuning the electrical properties of MHPs[2]. However, most of the reports have been focused on charge transfer at the interface or grain boundaries which have limited the attainable doping range. In this study, we first demonstrate molecular doping with a strong p-dopant (magic blue) for significantly improving the electrical conductivity of low-dimensional lead perovskites[3]. We identify that dopant incorporation into the bulk of the film as the structural origin of the improved conductivity and propose the solvent selection criteria for achieving an effective bulk molecular doping. Our efficient doping methods developed will open up a controllable route towards tuning electronic structure for optimizing perovskite-based electronic and optoelectronic devices).
References
[1] J. Euvrard, Y. Yan, D. B. Mitzi, Nat. Rev. Mater., 6, 531–549 (2021)
[2] Y. Kim, K. Kang et al., EcoMat, e12406 (2023)
[3] J. Lee, K.Y. Baek, J. Lee, K. Kang, T. Lee et al., Adv. Funct. Mater., 2302048 (2023)CVSeungjin Lee KENTECH Defect passivation for perovskite light-emitting diodes AbstractDefect passivation for perovskite light-emitting diodes
Solution-processable optoelectronic materials have several advantages such as light-weight, flexibility, transparency, low cost, and large-area processing compared to conventional crystalline inorganic elemental semiconductors. Among them, metal halide perovskites have been explored in light-emitting applications, a testament to their facile bandgap tuning, high color purity, and high absorption coefficient. However, these materials easily contain defect sites in surfaces, creating electronic traps within the bandgap. Furthermore, the performance of light-emitting diodes ─ which consist of several thin layers ─ depends on interface quality. A promising approach to overcome the issue is surface engineering that can passivate defects, adjust energy levels and control surface characteristics for better wettability.
In this presentation, we will introduce recent results regarding perovskite light-emitting diodes, and mainly discuss the beneficial effects of surface engineering on the device performance. In particular, we will introduce significant beneficial effects using amine-based passivating materials to passivate defect sites on the surface of perovskite films. Furthermore, we will present a method to grow perovskite films composed of uniform nano-sized single crystals by employing phenylmethylamine as a ligand. In the last chapter, we will discuss about the effect of bottom charge transport layers on the perovskite crystal growth and the resulting interface quaility using mulifunctional (defect-passivating and hole-transporting) conjugated polyelectrolytes bearing different ions.CVJiwoong Yang DGIST TBD CVJiwon Lee POSTECH Image sensors with thin-film photodiode based on novel materials AbstractImage sensors with thin-film photodiode based on novel materials
Image sensing technology has become increasingly advanced and is widely used in our daily lives. Currently, mainstream image sensing is silicon-based and uses visible or near-infrared light, but there has been a lot of research into new material-based image sensing to use different wavelengths to capture a wider range of information or to enable image sensors with different form factors. In particular, thin film photodiodes based on new materials such as organics, quantum dots and perovskites have attracted a lot of attention due to their advantages such as easy expansion to different wavelength bands, large area processing at low cost and monolithic integration on silicon.
This presentation will introduce thin film photodiode based image sensor technologies. The basics of the thin film photodiode image sensors will be described with a focus on the quantum dot based short wavelength infrared image sensor technology. In addition, the limitations of current thin film photodiode based image sensor technology will be presented along with technologies that can overcome these limitations.CVSe-Woong Baek Korea University Colloidal Quantum Dots-based Shortwave Infrared Optoelectronics for Long-range Communications AbstractColloidal Quantum Dots-based Shortwave Infrared Optoelectronics for Long-range Communications
The detection of infrared (IR) light is crucial for realizing various future applications, including recognition, bio-imaging, spectroscopy, and object inspection. In particular, utilizing photons beyond the silicon absorption band-edge (i.e., 1550 nm) becomes important to demonstrate long-range communications and quantum technologies. Colloidal quantum dots (CQDs), semiconducting nanocrystals, are promising alternative materials due to their quantum-confined bandgap tunability across visible to shortwave-infrared (SWIR) wavelengths. However, CQD-based IR optoelectronics currently face two challenges: the use of toxic elements such as Pb, Cd, and Hg, and lower performance compared to epitaxial semiconductors.
This talk showcases how to build IR devices using non-toxic CQD materials, including III-V, I-VI, and beyond. Various short-ligand passivation strategies enable stable CQD ink, thereby rendering high-quality conductive solids. We reveal that the extent of ligand passivation yields a surface-mediated photomultiplication effect, boosting the responsivity of devices. Furthermore, we have demonstrated an efficient avalanche breakdown in the CQD multiplication layer, achieving a fast response time below the nanosecond level with a notable gain of up to ~104. This represents a record gain x bandwidth product among all prior solution-processed IR photodetectors operated at 1550 nm.CVJong-Seok Kim Hanyang University Technological Challenges for OLED-on-Silicon (OLEDoS) Display Backplane Circuits in for AR & VR Devices AbstractTechnological Challenges for OLED-on-Silicon (OLEDoS) Display Backplane Circuits in for AR & VR Devices
The market for augmented reality (AR) and virtual reality (VR) devices, exemplified by Apple's Vision Pro, is experiencing rapid growth. Consequently, there is increasing interest in on-silicon microdisplays, which are gaining attention as key components of AR/VR devices. On-silicon microdisplays for AR/VR devices have significantly different requirements compared to conventional flat panel displays. Firstly, to provide users with a high level of immersion, a wide field of view (FoV) of around 120 degrees in both horizontal and vertical directions must be achieved. Secondly, considering the human eye's resolution, a resolution of approximately 60 pixels per degree (PPD) is required. Therefore, based on the required FoV and PPD, a high resolution of about 7.2k × 7.2k must be supported. Thirdly, microdisplays should be manufactured in a very small size of around 1 inch, considering the size of AR/VR devices. Given these requirements, microdisplays must implement high-resolution displays on small-sized panels. Microdisplays utilize panels fabricated on silicon substrates that enable fine processing rather than conventional panels made on glass or plastic substrates to achieve this. Representative on-silicon microdisplays include liquid crystal-on-silicon (LCoS), OLED-on-silicon (OLEDoS), and LED-on-silicon (LEDoS). In this study, we aim to explain the technical challenges of pixel circuits and driving circuits, which are the backplane circuits required to implement the on-silicon displays and discuss the methods being explored as solutions to these challenges.
CVJong Hyun Park Chonnam National University Surface Engineering for Efficienct and Stable Perovskite Nanocrystal-Based LIght-Emitting Didoes AbstractSurface Engineering for Efficienct and Stable Perovskite Nanocrystal-Based LIght-Emitting Didoes
Metal halide perovskites have gained attention as high-performance light-emitting diode (LED) materials owing to their excellent optical properties, such as facile bandgap tuning, defect tolerance, and high color purity. Furthermore, perovskite nanocrystals (PNCs) have attracted attention as high-performance LED applications due to their high exciton binding energy, high photoluminescence quantum yield (PLQY), and quantum confinement effect-driven bandgap tuning capability. However, due to the high surface-to-volume ratio, controlling sensitive surface characteristics is essential for achieving high-quality PNCs. In that sense, the importance of surface engineering has been highlighted, as the surface characteristics significantly affect the performance of PNCs, such as optical properties, electrical properties, and stability. In this talk, I will delve into the importance of surface engineering with several ligand materials and strategies to achieve high-quality PNCs for the LED application.
CVYong-Young Noh POSTECH TBD CVChaoyu Xiang CNITECH TBD Ting Zhang Ningbo Institute of Materials Technology and Engineering Application of Direct Lithography in Ultrahigh-Resolution Display AbstractApplication of Direct Lithography in Ultrahigh-Resolution Display
Colloidal quantum dots (QDs), as a class of zero-dimensional semiconductor materials, have generated widespread interest due to their adjustable band gap, exceptional color purity, near-unity quantum yield, and solution-processability. With decades of dedicated research, the potential applications of quantum dots have garnered significant recognition in both the academic and industrial communities. Furthermore, the related quantum dot light-emitting diodes (QLEDs) stand out as one of the most promising contenders for the next-generation display technologies. In recent years, driven by new concepts such as smart healthcare and "metaverse", the next generation of displays have set higher standards for pixel resolution to meet the ever-increasing demands of applications such as massive information and near-eye displays. However, the resolution of mainstream displays currently remains at the level of tens or hundreds of micrometers, and entering the submicron and nanometer scales faces many serious challenges. Ultrahigh-resolution displays are crucial for future near-eye virtual/augmented reality displays. QLED uses extremely small nanocrystals as emitters, and theoretically the light-emitting performance of the device is not limited by size, thus it has unique advantages in the field of high-resolution displays.
Different from OLEDs and micro-LED (in which shadow masking and massive transfer are usually applied to achieve full-color display, respectively), the pixilation techniques of QLEDs are mainly based on the manipulation of QD solutions or films. However, taking into account the droplet size and alignment accuracy of the industrial nozzle, it remains difficult for ink-jet printing to produce ultra-small QD pixels with well-defined boundaries. In order to meet the demands of high-resolution display, an alternative technology is needed to deliver delicate display effects and high fabrication efficiency. As a cornerstone technology in the modern semiconductor industry, photolithography is recognized as one powerful approach for the preparation of QD arrays.
For the QLED process, we have developed direct lithography processes for quantum dot layer and functional layer materials, which can realize the preparation of<5 µ m pixel arrays. Moreover, we propose and develop the first direct photolithography of EC WOx nanomaterials via an in situ ligand exchange reaction under UV radiation. A novel high-resolution EC display with precise WOx patterns (<4 µm, the highest resolution of inorganic EC materials and one of the highest resolutions of EC field) was fabricated.CV
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III. Materials and Devices for Smart Sensors
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Keynote Speakers
Invited Speakers
Name Affiliation Title Abstract CV Hongyun So Hanyang University 3D-printing-assisted sensors, actuators, and surfaces for various engineering applications Abstract3D-printing-assisted sensors, actuators, and surfaces for various engineering applications
Sensors and actuators that perform various functions are one of the important devices used in various fields such as mechanical, electrical, biomedical, chemistry, and industrial engineering. These sensors and actuators have a pattern of several millimeters or less, and many studies have recently been conducted to improve the sensitivity of sensors or the movement of actuators in combination with various three-dimensional (3D) structures. Although the top-down method using micro-processes is widely used as a process method for making sensors and actuators, there were limitations such as multi-steps, post-treatment processes, and the use of clean rooms and expensive equipment. FDM (fused deposition modeling)-type 3D printing is one of the most widely used additive manufacturing methods due to its inexpensive materials and fast printing speed. However, output printed in this way has the disadvantage of having a very rough surface. Looking closely at these fine patterns, several studies have recently been conducted that various patterns, which are difficult to make with the existing semiconductor process, can be achieved through the shortcomings of 3D printing. This presentation introduces various 3D printing-based manufacturing methods that can replace existing micro-processes, and shows the performance evaluation and reliability test results of sensors and actuators manufactured using them.
CVJunseong Ahn Korea University Nanoribbon Yarns with Versatile Metal/Ceramic Materials for High-Performance Transducer AbstractNanoribbon Yarns with Versatile Metal/Ceramic Materials for High-Performance Transducer
Nanomaterial-based yarns have been actively developed owing to their advantageous features, namely, high surface-area-to-volume ratios, flexibility, and unusual material characteristics such as anisotropy in electrical/thermal conductivity. The superior properties of the nanomaterials can be directly imparted and scaled-up to macro-sized structures. However, most nanomaterial-based yarns have thus far, been fabricated with only organic materials such as polymers, graphene, and carbon nanotubes. This paper presents a novel fabrication method for fully inorganic nanoribbon yarn, expanding its applicability by bundling highly aligned and suspended nanoribbons made from various inorganic materials (e.g., Au, Pd, Ni, Al, Pt, WO3, SnO2, NiO, In2O3, and CuO). The process involves depositing the target inorganic material on a nanoline mold, followed by suspension through plasma etching of the nanoline mold, and twisting using a custom-built yarning machine. Nanoribbon yarn structures of various functional inorganic materials are utilized for chemical sensors (Pd-based H2 and metal oxides (MOx)-based green gas sensors) and green energy transducers (water splitting electrodes/triboelectric nanogenerators/supercapacitor/thermoelectric generator). This method is expected to provide a comprehensive fabrication strategy for versatile inorganic nanomaterials-based yarns.
CVYong-Sang Ryu Korea University Colorimetric Hydrogen sensor for smark window display AbstractColorimetric Hydrogen sensor for smark window display
Palladium is the most prominent material in both scientific and industrial research on gas storage, purification, detection, and catalysis due to its unique properties as a catalyst and hydrogen absorber. Advancing the plasmonic optical phenomena of palladium reacting with hydrogen, transduction of the gas-matter reaction into light-matter interaction is attempted to visualize the dynamic surface chemistry and reaction behaviors. The simple geometry of the metal-dielectric-metal structure, Fabry-Perot etalon, is employed for a colorimetric reactor, to display the catalytic reaction of the exposed gas via water-film/bubble formation at the dielectric/palladium interface. The adsorption/desorption behavior and catalytic reaction of hydrogen and oxygen on the palladium surface display highly repeatable and dramatic color changes based on two distinct water formation trends: the foggy effect by water bubbles and the white-out effect by water film formation. Simulations and experiments demonstrate the robustness of the proposed Fabry-Perot etalon as an excellent platform for monitoring the opto-physical phenomena driven by heterogeneous catalysis.
CVFei Wang Southern University of Science and Technology TBD CVJae-Woong Jeong KAIST Reshaping Bio-Interfaces: Exploring the Potential of Mechanically Transformative Electronics AbstractReshaping Bio-Interfaces: Exploring the Potential of Mechanically Transformative Electronics
Traditionally, electronics are designed with fixed form factors tailored to specific uses. However, the fixed mechanical properties of electronics make them highly target-specific, limiting their broad use in a more compliant manner. To address this limitation, we present a new type of device called 'transformative electronics' that can change their shape and stiffness as needed. By building electronics on a platform made of gallium, which can transition between solid and liquid states based on temperature, these devices can switch between rigid and flexible modes on demand, combining the benefits of both types of electronics. We explore how this technology could be used in wearable, implantable, and sensing devices to improve interactions between electronics and biological systems. This presentation will discuss the design principles, materials, and manufacturing methods of transformative electronics, emphasizing their potential for biological applications. This innovation opens up exciting possibilities for various biomedical uses, promising significant advancements in the field.
CVXiaogan Li Dalian University of Technology Zinc oxide based heterostructured hollow microspheres for formaldehyde detection at room temperature AbstractZinc oxide based heterostructured hollow microspheres for formaldehyde detection at room temperature
The hollow Zinc oxide microspheres heterostructured with TiO2 and In2O3 were synthesized by hydrothermal method using carbon nanospheres as sacrificed templates. With UV activation, the response of ZnO-TiO2 based chemiresistive-type sensors to 10 ppm formaldehyde is 11.02 at room temperature which is 5.48 times larger than that of the pure hollow ZnO. The response and recovery time of the sensor were significantly reduced to 14 s and 16 s. With Au and In2O3 incorporation, the response of the Au-ZnO@-In2O3 sensor exhibited a further increase to 14.8 when exposed to 10 ppm formaldehyde at room temperature. However, the response/recovery times became longer with 32 s and 42 s, respectively. The sensing mechanism of the sensor to formaldehyde have been investigated by AC impedance spectroscopy, in-situ DRIFTS, and DFT theoretical calculation. It reveals that “electronic sensitization” would plays major role in enhancing the response whereas “chemical sensitization” would improve the kinetic features making the sensor have a faster response/recovery rate. Selectivity, stability and repeatability of the hollow ZnO based heterostructured microspheres based sensor under UV-activation have also been examined.
Dong Kyun Ko New Jersey Institute of Technology TBD CV
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IV. Materials, Processing, and Devices for Unconventional Electronics
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Keynote Speakers
Jonghyun Ahn
Yonsei UniversityGraphene-Based Biosensors for Body Temperature and Brain Activity Monitoring
AbstractGraphene-Based Biosensors for Body Temperature and Brain Activity Monitoring
Biosignals, such as body temperature and ECoG, provide valuable information about the overall condition of the human body and facilitate the diagnosis of various diseases. In this presentation, I will introduce two innovative devices: a wearable thermal patch with dual functionality, providing continuous body temperature monitoring and thermotherapy for effective self-care treatment, and an ECoG sensor with clinical diagnostic capabilities for monitoring abnormal brain rhythms in patients. The thermal patch is composed of a graphene-based capacitive sensor, a graphene thermal pad, and a flexible read-out board equipped with a wireless communication module. This wearable sensor continually tracks temperature variations over a broad skin area with high resolution and sensitivity. It also delivers thermotherapy through a graphene-based heater located at the device's base. Furthermore, the ECoG sensor comprises graphene electrodes and read-out circuits with a wireless communication module. This sensor is directly attached to the brain cortex, enabling continuous monitoring of ECoG signals. Animal studies have confirmed the system's effectiveness in diagnosing various diseases. This technology holds promise for the development of convenient and wearable healthcare devices.
CV
Tae-il Kim
Sungkyunkwan Univ.Materials and device designs toward motion artifact-free bioelectronics
AbstractMaterials and device designs toward motion artifact-free bioelectronics
Bioelectronics needs to continuously monitor mechanical and electrophysiological signals for patients. However, the signals always include artifacts by patients’ unexpected movement (such as walking and respiration under approximately 30 hertz). The current method to remove them is a signal process that uses a bandpass filter, which may cause signal loss. We present an unconventional bandpass filter material—viscoelastic gelatin-chitosan hydrogel damper, inspired by the viscoelastic cuticular pad in a spider—to remove dynamic mechanical noise artifacts selectively. The hydrogel exhibits a frequency-dependent phase transition that results in a rubbery state that damps low-frequency noise and a glassy state that transmits the desired high-frequency signals. It serves as an adaptable passfilter that enables the acquisition of high-quality signals from patients while minimizing signal process for advanced bioelectronics.
CVInvited Speakers
Name Affiliation Title Abstract CV Lizhi Xu The University of Hong Kong Bio-Integrated Soft Electronics Based on Biomimetic 3D Nanofiber Networks AbstractBio-Integrated Soft Electronics Based on Biomimetic 3D Nanofiber Networks
Nanofiber networks are essential structures in natural biological tissues, which exhibit a combination of mechanical flexibility, fracture resistance, and mass permeability to enable many important physiological functions. Inspired by natural soft tissues, we exploit biomimetic nanofiber networks as building blocks for the construction of a variety of bio-integrated soft devices. A key component in these materials and devices is aramid nanofiber (ANF). With appropriate solvent-based processing steps, the ANFs self-organize into hyperconnective networks, which capture some of the key features of load-bearing soft tissues. They also exhibit tissue-mimetic physical properties and microstructural reconfigurability, which are beneficial for device applications. The composites can be functionalized with bioactive molecules or soft electronic components for interfacing with cells and tissues. In this presentation, I will introduce some of our recent works ranging from electroconductive hydrogels and wearable devices to theoretical modeling and meso-structural designs. These works address the fundamental physical mismatches between biomedical devices and biological soft tissues, paving the way for the development of advanced wearable human-machine interfaces, implantable electronics, tissue engineering platforms, and other biomedical systems.
CVDae-hyeong Kim Seoul National University Flexible, Foldable, and Stretchable QLEDs AbstractFlexible, Foldable, and Stretchable QLEDs
Recent advances in soft electronics have attracted great attention due in large to its potential applications in personalized mobile and wearable electronic devices. The mechanical mismatch between conventional electronic/optoelectronic devices and soft human tissues/organs, however, often causes various challenges, such as the mechanical fracture in the device under deformations, and discomfort and consequent stress to users. Ultra-flexible and stretchable electronic and/or optoelectronic devices have low system modulus and intrinsic softness and solve these issues. Here, our unique strategies in the synthesis of nanoscale materials such as quantum dots and metal nanowires, their seamless patterned integration with ultrathin electronics, and unconventional device designs toward flexible, foldable, and stretchable quantum dot light emitting devices are presented. These wearable and stretchable light emitting devices can be integrated with various skin-mounted soft sensors and electronics. Such soft integrated systems are the results of recent breakthroughs in unconventional soft electronics, and will create many new opportunities toward next-generation human-friendly mobile electronics.
CVInkyu Park KAIST TBD CVJang-Ung Park Yonsei University Wearable Ophthalmic Devices for Disease Monitoring and Health Management AbstractWearable Ophthalmic Devices for Disease Monitoring and Health Management
The eye contains a complex network of physiological information and biomarkers for monitoring disease and managing health, and ocular devices can be used to effectively perform point-of-care diagnosis and disease management. This talk explains the target biomarkers and various diseases, including ophthalmic diseases, metabolic diseases, and neurological diseases, based on the physiological and anatomical background of the eye. This talk also introduces the recent technologies utilized in eye-wearable medical devices and the latest trends in wearable ophthalmic devices for the purpose of disease management. After introducing ocular devices such as the retinal prosthesis, we further discuss the current challenges and potential possibilities.
CVChengkuo Lee National University of Singapore TBD Chang, Jae-Byum KAIST TBD CVJae-Young Yoo Sungkyunkwan Univ. Intelligent Medical Solution using Multimodal Electronics and Control Networks AbstractIntelligent Medical Solution using Multimodal Electronics and Control Networks
Despite recent strides in medical diagnostic systems, cardiovascular diseases (the leading global cause of death) and respiratory diseases (ranking 3rd and 6th) continue to claim 43 lives per minute worldwide. Conditions like acute cardiac arrest or respiratory failure often arise suddenly, lacking warning symptoms, posing challenges for immediate treatment and response. With an alarming 8% survival rate, these issues represent significant societal concerns. Furthermore, sudden infant death syndrome (SIDS) contributes significantly to infant mortality within the first five years, underscoring the pressing need for continuous monitoring of cardiovascular and respiratory functions, along with the development of rapid response systems.
While wireless biosignal detection systems offer a promising solution for continuous health monitoring, the current emphasis primarily revolves around heartbeat detection. This leaves the technological landscape for detecting various biosignals, such as respiration and blood pressure, underdeveloped. Enhancing sensor sensitivity to subtle biosignals introduces susceptibility to external physical or electrical noise, complicating the task of obtaining reliable vital signals. Additionally, the development of medical solutions transitioning seamlessly from diagnosis to immediate therapeutic assistance demands a convergence of knowledge from medicine, electronic engineering, and control engineering, rendering it a futuristic technology.
The seminar introduces advances in three key areas that overcome the limitations of existing wireless monitoring systems: 1) the development of reliable high-performance biosignal sensors and biosignal separation algorithms, 2) the utilization of sensor networks for spatiotemporal information of biosignals, and 3) a real-time stimulation therapy system.CVXinge Yu City University of Hong Kong TBD CVXian Huang Tianjin University TBD
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V. Two-dimensional Materials and van der Waals Heterostructures
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Keynote Speakers
Lance Li
University of Hong Kong/TSMCBoosting bulk photovoltaic effect in transition metal dichalcogenide by edge semimetal contact
AbstractBoosting bulk photovoltaic effect in transition metal dichalcogenide by edge semimetal contact
The bulk photovoltaic effect (BPVE) has traditionally been observed in non-centrosymmetric oxide materials, yet its cell efficiency was too negligible for practical use. Recently, significantly larger BPVE coefficients have been noted in two-dimensional (2D) materials, albeit under specific extrinsic operational conditions such as strain engineering and the use of heterointerfaces, depolarization fields, and edge-embedded structures. However, harnessing these materials' intrinsic BPVE potential for practical applications continues to pose a significant scientific challenge. In this context, we have achieved a significant milestone in enhancing the intrinsic BPVE of 3R-MoS2 by utilizing edge contact (EC) geometry with a bismuth semimetal electrode. Unlike the traditional top contact (TC) geometry, EC geometry enables full exploitation of the in-plane spontaneous polarization of the underlying layers, resulting in a photocurrent BPVE enhancement of more than 100 times. As a result, the performance of the EC-based BPVE device is now constrained by the depth of light penetration instead of electrode contact. Furthermore, by engineering a 3R-MoS2/WSe2 heterojunction, we have successfully demonstrated the synergistic integration of BPVE with the photovoltaic effect (PVE), marking a significant leap forward in the pursuit of practical applications in this domain.
CVInvited Speakers
Name Affiliation Title Abstract CV Qijun Sun BINN, Chinese Academy of Science Triboelectric Potential Driven FETs for Interactive Neuromorphic Synaptic Devices and Systems AbstractTriboelectric Potential Driven FETs for Interactive Neuromorphic Synaptic Devices and Systems
Fully imitating functions of biological synapses or afferents is critical to the evolution of neuromorphic
computation and artificial intelligence. Benefiting from recent progress in bioinspired
sensors, artificial synapses and interactive systems, more intelligent neuromorphic devices
(or systems) capable of processing sensing signals and delivering interactive feedback are
urgent to be developed and have been rapidly emerging recently. Different types of
electronic devices (e.g., memristor, ionic devices, floating-gate transistor) have been
demonstrated to successfully mimic synaptic functions assisted with electrical, optical and
mechanical plasticization. Integration with sensory, processing, and actuating components
further endows the traditional neuromorphic devices with more complete bionic
somatosensory ability. The seamless and adaptive interactions between neuromorphic
synaptic devices and external environment is believed to be essential in establishing future
brain-like computers and artificial intelligent systems. This presentation will introduce
interactive neuromorphic synaptic devices and systems based on our recent research work of artificial afferents, bioinspired analogous nerves, myoelectric-mechanical interface, etc.
This talk will mainly cover the significant progress concerning on artificial synapses correlated with
mechanical, optical, pressure and strain trigger-signals. Based on our researches of artificial afferent,
mechanoplastic neuromorphic devices, and bioinspired mechano-photonic synapses, “interactive neuromorphic device” will be the core in this presentation. This talk will start from the principle of neurosynaptic devices activated by different sensing signals and introduce the influence of external signals on synaptic plasticity. It will also introduce the research progress of interactive neuromorphic synaptic devices/systems inspired by pressure, touch, displacement, light, heat, and mixed signals, and look forward to the future applications of interactive neuromorphic synaptic devices/systems. The interactive neuromorphic synaptic device will involve electronic devices, neuromorphic computation, sensors, and human-machine interactions, which is highly promising for revolutionary artificial synapse and neuromorphic systems.
Keywords: Triboelectric potential, FET, Interactive, Synaptic Devices, Neuromorphic SystemsCVGuohua Hu The Chinese University of Hong Kong Realizing neuromorphic computing with solution-processed low-dimensional materials AbstractRealizing neuromorphic computing with solution-processed low-dimensional materials
With the rapid advancement of artificial intelligence and machine learning, the traditional von Neumann computing is facing challenges in the computational power and energy consumption. Inspired by the human brain, neuromorphic computing by mapping the structural and functional architectures of the neural networks has emerged as a promising alternative paradigm. Solution-processed low-dimensional materials, with their unique electronic properties, allow device fabrication and engineering towards the implementation of neuromorphic computing. In this talk, I will discuss the recent progress of our research on neuromorphic computing using solution-processed low-dimensional materials and devices. The first part of my talk will focus on solution processing of low-dimensional materials, such as two-dimensional materials and carbon nanotubes, for the development of printed electronics. Specifically, I will discuss the fabrication of memristor and memristive transistor devices, and the exploitation of the device characteristics in the design of artificial neurons and synapses. On this basis, the second part of my talk will discuss the implementation of neuromorphic computing approaches, including the convolutional computing, spiking neuromorphic computing, and reservoir computing, using the devices and the artificial neurons and synapses. The demonstrations leveraging the device characteristics hold the promise to enable efficient computation in autonomous driving, virtual reality, medical diagnosis, industrial automation, and beyond.
CVKai Liu Tsinghua University Single-gate programmable graded doping for 2D reconfigurable MoTe2 devices AbstractSingle-gate programmable graded doping for 2D reconfigurable MoTe2 devices
Nonvolatile reconfigurable devices can operate in multiple designed functions, offering great opportunities to improve integration levels and decrease power consumption in next-generation electronics. With their ultrathin nature and strong gate control, two-dimensional (2D) semiconductors are promising materials for nonvolatile reconfigurable devices. However, it is a dilemma to realize rich reconfigurable functions with a simple device configuration. In this talk, we will report a flexible effective-gate-voltage programmed graded-doping (EGV-pGD) strategy, which utilizes the programmable synergy among gate, drain, and source terminals, to endow a single-gate 2D MoTe2 device with abundant reconfigurable functions. The reconfigurability of our device, allowing functions of polarity-switchable diodes, memory, in-memory Boolean logics, homosynaptic plasticity, and heterosynaptic plasticity, has surpassed all other reconfigurable devices. Accompanying the rich reconfigurable functions, our device also exhibits extraordinary performance. In particular, as a diode, the device exhibits a rectification ratio up to ~104, and as an artificial heterosynapse, it shows heterosynaptic metaplasticity with an ultralow modulatory power consumption that can be reduced to 7.3 fW, only 1/2700 of the lowest value previously reported. Our work provides an effective strategy to realize reconfigurable multifunctionality of 2D devices with the lowest complexity of device configuration and boosts the understanding of gate-controlled graded doping for 2D ambipolar semiconductors.
References
R. X. Peng, K. Liu*, et al. Nature Electronics 6, 852-861 (2023)
Y. H. Wu, K. Liu*, et al. Advanced Materials 35, 2210735 (2023).
X. W. Wang, K. Liu*, et al. Advanced Materials 33, 2102435 (2021).CVSeoung-Ki Lee Pusan National University Laser-Driven Synthesis of 2D Material-Based Electronics on Arbitrary Substrate AbstractLaser-Driven Synthesis of 2D Material-Based Electronics on Arbitrary Substrate
Two-dimensional (2D) materials are increasingly valued for their pivotal role in flexible electronics, providing substantial benefits over traditional materials. These materials are highly sensitive, enabling the accurate detection of specific analytes and various physical forces, which makes them perfect for advanced sensors on flexible bases that support various shapes and sizes. Traditional methods for producing 2D materials involve high-temperature techniques (exceeding 750°C) and often damage the films during transfer to the desired substrates, leading to contamination, wrinkles, and inconsistencies. These defects are especially troublesome in sensor arrays, where they can cause operational inaccuracies.
In response to these issues, we present a new approach for directly synthesizing 2D material-based sensor arrays on flexible substrates using a laser-driven selective heat treatment process. This method involves the thermal decomposition of precursor compounds to create the 2D materials, specifically forming a MoS2 sensor array on a stretchable substrate. A critical feature of this technique is the use of a fiber laser with a 1.06 µm wavelength, which selectively heats the precursor without significantly affecting the MoS2, allowing for rapid heating and decomposition into MoS2. We also showcased the creation of Laser-Induced Graphene (LIG) with tunable morphology on a polyimide substrate. By adjusting the laser's focus, we varied the LIG structure from porous to fibrous, with the latter resembling carpet fibers and exhibiting enhanced sensitivity to fine mechanical changes. This method not only improves the accuracy but also streamlines the manufacturing process of stretchable devices that incorporate 2D materials.Tae-Wook Kim Jeonbuk National University Giant 2D Single-Crystalline Metallic Nanosheets: Synthesis and Applications AbstractGiant 2D Single-Crystalline Metallic Nanosheets: Synthesis and Applications
In this study, we report hierarchical porous Cu film via assembly of single-crystalline, nanometer-thick, and micrometer-long copper nanosheets and their use in EMI shielding. Layer-by-layer assembly of Cu nanosheets enabled formation of a hierarchically-structured porous Cu film with features such as multi-layer stacking; 2D networking; and a layered, sheet-like void architecture. The hierarchical-structured porous Cu foil exhibited outstanding EMI shielding performance compared to the same thickness of dense copper and other materials, exhibiting EMI shielding effectiveness (SE) values of 100 and 60.7dB at thicknesses of 15 and 1.6 μm, respectively. In addition, the EMI SE of the hierarchical porous Cu film was maintained up to 18 months under ambient conditions at room temperature and showed negligible changes after thermal annealing at 200°C for 1 hr. These findings suggest that Cu nanosheets and their layer-by-layer assembly are one of the promising EMI shielding technologies for practical electronic applications. And also, we will discuss on monolayer assembly of metallic nanosheets and their applications.
Gwangwoo Kim Chungbuk National University Spatially Controllable Growth of Quantum-Confined 2D Heterostructures AbstractSpatially Controllable Growth of Quantum-Confined 2D Heterostructures
Two-dimensional (2D) heterostructures have recently attracted interest as candidate materials for classical optoelectronics and in quantum information technology. Despite significant research, realizing deterministic, in-plane quantum confinement in synthetic 2D heterostructures at the nanoscale remains challenging. In this study, we present a breakthrough by demonstrating the spatially controlled growth of quantum-confined 2D heterostructures. These structures comprise 0D quantum dots embedded within a 2D matrix, achieved through a catalytic conversion reaction on a platinum template.[1] Furthermore, an in-depth investigation into the electrical and optical quantum properties of the resulting heterostructure was conducted. The confined 0D quantum dots within the 2D matrix, coupled with the formation of lateral heterointerfaces, result in novel electronic states in these heterostructures. [1-3] These emergent states hold significant potential for applications in tunneling transistors and quantum photonic devices. This work contributes to advancing our understanding of controlled quantum confinement in 2D heterostructures, paving the way for innovative developments in quantum technologies.
References
[1] G. Kim, S. S. Kim, J. Jeon, S. I. Yoon, S. Hong, Y. J. Cho, A. Misra, S. Ozdemir, D. Ghazaryan, A. Mishchenko, D. V. Andreeva, Y. J. Kim, H. J. Chung, A. K. Geim, K. S. Novoselov*, B. S. Sohn*, H. S. Shin*, Nature Communications 2019, 10, 230.
[2] G. Kim+, K. Y. Ma+, M. Park, M. Kim, J. Jeon, J. Song, J. E. Barrios-Vargas, Y. Sato, Y.-C. Lin, K. Suenaga, S. Roche, S. Yoo, B.-H. Sohn, S. Jeon, H. S. Shin*, Nature Communications 2020, 11, 5359.
[3] G. Kim, H. M. Kim, P. Kumar, M. Rahaman, C. E. Stevens, J. Jeon, K. Jo, K.-H. Kim, N. Trainor, H. Zhu, B. H. Sohn, E. A. Stach, J. R. Hedrickson, N. R. Glavin, J. Suh, J. M. Redwing, D. Jariwala*, ACS Nano 2022, 16, 9651.CVJieun Yang Kyunghee University Synergistic Enhancement of Reversible Capacity and Cycling Stability in MoS 2 /FeS 2 Heterostructure Anodes for Lithium/Sodium-Ion Batteries AbstractSynergistic Enhancement of Reversible Capacity and Cycling Stability in MoS 2 /FeS 2 Heterostructure Anodes for Lithium/Sodium-Ion Batteries
In the quest to improve lithium/sodium-ion batteries, the study introduces a hydrothermally
synthesized MoS 2 /FeS 2 composite. This approach capitalizes on the strengths of both MoS 2 and FeS 2
materials. MoS 2 , known for its layered structure, is adept at hosting lithium and sodium ions but
struggles with long-term structural integrity during battery use. Conversely, FeS 2 boasts a high
theoretical specific capacity and better conductivity but suffers from stability issues upon repeated
cycling due to substantial volume changes. In this study, we aimed to mitigate these issues by forming
a composite. The MoS 2 /FeS 2 composite material was designed to deliver a large surface area for ion
exchange while also preserving electrical conductivity. This novel structure enhances ion diffusion
rates and adds robustness to the anode during the charge and discharge cycles. The study suggests that
the composite's ability to conduct electricity was improved by FeS 2 , and its structural stability was
enhanced by MoS 2 . Optimizing synthesis conditions yielded the MoS 2 /FeS 2 composite which
exhibited a high reversible capacity, significantly outperforming the separate materials. The composite
maintained a high capacity of 1356 mAh g -1 after 100 cycles at a lower current density (0.2C), and it
showed resilience at higher loads with a capacity of 714 mAh g -1 at 1C. The MoS 2 /FeS 2 composite
combines a significant capacity with robust cycling stability, making it a promising anode candidate
for next-generation battery technologies.CVSang Yeon Park Hongik University Copper Sulfide Electrodes for Electronic and Optoelectronic Applications AbstractCopper Sulfide Electrodes for Electronic and Optoelectronic Applications
2D nanostructures have garnered intense interests due to their 2D structure that enables super flexibility, optical transparency, and facile integration with disparate materials through van der Waals forces. In this presentation, I will introduce a new class of covellite 2D copper monosulfide (CuS) nanosheet film as a promising candidate for transparent, flexible conductive electrodes, which can be employed in various flexible and wearable electronic and optoelectronic devices. Especially, the presentation will cover from the synthesis of 2D CuS using facile sulfurization method to its employment in various electronics and optoelectronics devices including the source-drain electrode materials for 2D MoS2 channel. We achieved record high electron mobility up to 100 cm2V-1s-1 at room temperature in a back-gate device configuration. We will also cover effective doping method to tune its electrical and optical properties.
CVHyun Seok Lee Chungbuk National University Functionalization and Manipulation of Optoelectronic Properties and Their Applications in CVD-Grown 2D Semiconductors AbstractFunctionalization and Manipulation of Optoelectronic Properties and Their Applications in CVD-Grown 2D Semiconductors
Two-dimensional (2D) van der Waals materials are substances with ultra-thin layers that have atomic layer thickness. They include a variety of material groups such as metals, semiconductors, dielectrics, magnetics, ferroelectrics, etc. These can be easily exfoliated from the layered structure of bulk materials or synthesized using chemical vapor deposition (CVD). These ultra-thin 2D characteristics can modulate various quantum phenomena by adjusting thickness, stress, electric field, and interlayer bonding. Therefore, they not only lead to new physical phenomena but also have far-reaching applications in electronics, optoelectronics, spintronics, sensors, and other wide-ranging areas. As an alternative to exfoliation, the CVD method enables large-area synthesis, but controlling defects during growth remains a critical challenge. In this work, the author explores specific optoelectronic and surface properties manipulated by defects, interfaces, doping, and plasmonic hybridizations in CVD-grown 2D semiconductors. Furthermore, the author discusses the application of these characteristics in optical communications and electronic devices.
CVYonghun Kim Korea Institute of Materials Science All Solid-State Synapse Device Arrays Using 2D Channel/LiSiOx Electrolyte for Next-Generation Neuromorphic Edge Computing AbstractAll Solid-State Synapse Device Arrays Using 2D Channel/LiSiOx Electrolyte for Next-Generation Neuromorphic Edge Computing
High-precision artificial synaptic devices are essential for realizing robust neuromorphic hardware systems with reliable parallel analogue computation beyond the von Neumann serial digital computing architecture. In this talk, we will present a robust three-terminal two-dimensional (2D) MoS2 artificial synaptic device combined with a lithium silicate (LSO) solid-state electrolyte thin film is proposed for neuromorphic edge computing applications. Critical issues related to reliability and variability, such as nonlinearity and asymmetric weight updates, have been great challenges in the implementation of artificial synaptic devices in practical neuromorphic hardware systems. The rationally designed synaptic device exhibits excellent linearity and symmetry upon electrical potentiation and depression, benefiting from the reversible intercalation of Li ions into the MoS2 channel. Also, the ultra-flexible synapse device arrays using this heterostructures is also introduced.
CV
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VI. Advanced Structural Materials
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Keynote Speakers
Invited Speakers
Name Affiliation Title Abstract CV Hiromoto Kitahara Kumamoto University Grain refinement of zinc single crystals and polycrystals by SPD process AbstractGrain refinement of zinc single crystals and polycrystals by SPD process
Zinc has an hcp structure and shows crystal orientation dependence on deformation behavior. A single pass of equal channel angular pressing (ECAP) at 223 K was applied to six kinds of zinc bulk single crystals with different crystal orientations, and the deformation behavior was investigated, such as grain refinement. A zinc single crystal with several hundred cubic millimeters was found to be divided into a large number of grains by a single pass of ECAP. Twinning and recrystallization above the shear plane are key for grain refinement. ECAP deformation behavior of zinc polycrystals at 276 K was also investigated. Recrystallization occurred during ECAP and equiaxed grains were observed; the mean grain size was 12.8 micrometers after 8-pass of ECAP. On the other hand, accumulative roll-bonding (ARB) was applied to zinc polycrystalline sheets. The mean grain thickness was 6.9 micrometers after 7-cycle. Recrystallization occurred but no grain grew beyond bonding interfaces; the grain size depends on the thickness of layers. ARB is the most efficient SPD for the grain refinement of zinc.
CVHongmei Chen Jiangsu University of Science and Technology Effect of heat treatment on the microstructure evolution and properties of rare earth magnesium alloys cast with electromagnetic stirring AbstractEffect of heat treatment on the microstructure evolution and properties of rare earth magnesium alloys cast with electromagnetic stirring
The Mg-6Gd-3Y-xZn-0.6Zr (X=1, 1.5, 2, 3) alloy, melted using electromagnetic stirring (EMS) solidification, was subjected to solid solution treatment and aging. This process was followed by an analysis focusing on the microstructural evolution and property changes. The chosen solid solution treatment involved water quenching the alloy after maintaining it at 520°C for 8 hours. After the solid solution treatment, the second phases dissolved back, making an increase in plasticity. After the aging treatment, the age-hardening curve flattens out with increasing Zn content. The more residual LPSO phases, the less β' phase precipitated by aging. Solid solution aging significantly enhanced the mechanical characteristics of the alloys compared to their initial as-cast state. The 1.5Zn alloy, aged for 48 hours, exhibited the best performance, achieving strength and elongation values of 213.5 MPa and 9.7%, respectively.
CVShinji Muraishi Tokyo Inst. of Tech. Simultaneous hardening by precipitates and dislocations in A7050 aluminum alloy AbstractSimultaneous hardening by precipitates and dislocations in A7050 aluminum alloy
Thermomechanical treatment of age-hardenable aluminum alloys is important to improve the precipitation density, where plastic working is generally performed after the solid solution heat treatment. However, there are few reports on the appropriate timing of plastic working and pre-aging on precipitation strengthening. For instance, when the plastic working is performed after the pre-aging, dislocation density will be increased by existing fine GP zones formed during the pre-aging, which leads to the simultaneous hardening by precipitates and dislocations. In addition, dislocations pinned by GP-zones may suppress the recovery of dislocations and promote the diffusion of solute atoms.
When the strengthening by dislocations and precipitates coexist, the respective strengthening mechanisms cannot be simply added. In other words, when precipitates and immobile dislocations serve as pinning points for mobile dislocations, the average spacing of these obstacles will affect the external force to propagate the dislocations. Furthermore, the GP zone and η' phase are misfit precipitates, and the distribution of positive and negative internal stress around the precipitates influence the dislocation motion.CVHyunJoo Choi Kookmin University Aluminum Matrix Composites Manufactured using Nitridation-Induced Self-Forming Process AbstractAluminum Matrix Composites Manufactured using Nitridation-Induced Self-Forming Process
Conventional manufacturing processes for aluminum matrix composites (AMCs) involve complex procedures that require unique equipment and skills at each stage. This increases the process costs and limits the scope of potential applications. In this study, a simple and facile route for AMC manufacturing is developed. In this process, a mixture of Al powder and the ceramic reinforcement is simply heated under nitrogen atmosphere to produce the composite. During heating under nitrogen atmosphere, the surface modification of both Al and the reinforcement is induced by nitridation. When the oxide layer covering Al powder surface is transformed to nitrides, temperature in the local region increases rapidly, resulting in a partial melt of Al powder. The molten Al infiltrates into the empty space among Al powder and reinforcement, thereby enabling consolidation of powders without external forces. It is possible to fabricate AMCs with various types, sizes, volume fractions, and morphologies of the reinforcement. Furthermore, the manufacturing temperature can be lowered below the melting point of Al (or the solidus temperature for alloys) because of the exothermic nature of the nitridation, which prevents formation of un-wanted reactants. The simplicity of this process, which is incomparable to that of the conventional processes, will not only provide sufficient price competitiveness for the final products but also contribute to the expansion of the application scope of AMCs.
CVNokeun Park Yeungnam University TBD Jeoung Han Kim Hanbat National University Characterization of Oxide-Dispersion-Strengthened Ti-6Al-4V Alloy Produced via Additive Manufacturing Processes AbstractCharacterization of Oxide-Dispersion-Strengthened Ti-6Al-4V Alloy Produced via Additive Manufacturing Processes
This research serves as a preliminary investigation to assess the viability of oxide dispersion strengthened (ODS) alloy based on Ti-6Al-4V. ODS Ti-6Al-4V powder was fabricated using the electrode induction melting gas atomization (EIGA) method. Rod-shaped Ti ingots, enriched with Y, were prepared through vacuum arc remelting (VAR) to examine the composition and content of oxides that can dissolve in molten Ti during melting and precipitate within powders during cooling in gas atomization. In this study, we attempted the in-situ synthesis of oxide nanoparticles in ODS Ti-6Al-4V alloy during the additive manufacturing (AM) process. By pre-alloying the powder and controlling the partial pressure of oxygen, we successfully prevented abnormal growth behavior of oxide nanoparticles. Following AM, a preicipitation of oxide nanoparticles were formed in-situ and uniformly distributed within the ODS Ti-6Al-4V. The average size and number density of nanoparticles were approximately 20 nm and 10^22/m^3, respectively. This AM process yielded relatively higher strength with slightly lower ductility. Notably, a well-developed dimple structure was observed, and no evidence of cleavage fracture surfaces was noted in the fracture surface of the tensile specimen. Furthermore, we provide a detailed examination and discussion of the microstructural characterization and formation mechanism of nanoparticles in this newly AMed ODS Ti-6Al-4V alloy.
CVTae-ho Lee KIMS An interpretation of deformation mechanism based on dislocation plasticity AbstractAn interpretation of deformation mechanism based on dislocation plasticity
A challenge to tailor the properties of steels for structural applications requires a profound understanding of deformation mechanism in materials design and property enhancement. Among various deformation mechanisms, strain-induced martensitic transformation (SIMT) has received increasing attention owing to its favorable contributions to strength-elongation balance. Although several models for SIMT have been proposed and attempts have been made of providing experimental evidences to support the models, discrepancies remain about the essential parameters dictating nucleation of martensite and about the dislocation activities governing plasticity. To resolve the uncertainties underlying SIMT, we propose dislocation-based models to understand SIMT based on the systematic two-beam analyses on dislocations. Here, we propose a dislocation-based model for sequential fcc-hcp-bcc martensitic transformation. Apart from previous models for direct fcc-to-bcc MT, two-step transformation composed of fcc-to-hcp followed by hcp-to-bcc was a main transformation path. For the first stage, Frank partial dislocation played a decisive role in the formation of fcc-to-hcp MT. And, two invariant-plane strains are required to complete the hcp-to-bcc MT. By incorporating dislocation dissociation model into the concept of stacking fault energy, we suggest a synthesized concept of deformation scenario that can provide fundamental and predictive insight into plasticity and transformability.
CVNaoki Takata Nagoya University Control of elemental partitioning in aluminum alloys using solidification path in laser powder bed fusion process AbstractControl of elemental partitioning in aluminum alloys using solidification path in laser powder bed fusion process
Laser powder bed fusion (L-PBF) process enables the formation of non-equilibrium microstructure and metastable phases in rapid solidification (at an extremely high cooling rate of 105-107 K/s). The L-PBF-processed Al-Fe alloys exhibit significantly refined solidification microstructures, contributing to high mechanical performance. In the eutectic reaction in rapid solidification, alloy elements could be partitioned into a liquid phase rather than a primary solidified phase, resulting in the enhanced formation of the second solid phase (Al6Fe phase in an Al-Fe system). In contrast, the alloy elements might be partitioned into the primary solidified a-Al phase (rather than the liquid phase) through a peritectic reaction in solidification. The partitioned solute elements in the a-Al matrix would play a significant role in solid-solution strengthening. These insights can open an opportunity for controlling refined microstructures of Al alloys by elemental partitioning via solidification paths of eutectic or peritectic reactions in the L-PBF process. In this concept, we have selected alloy elements exhibiting different solidification paths in Al-X binary phase diagrams. Cu and Ti elements were used as third alloy elements for the Al-Fe-X ternary system in the present study. Cu element exhibits a eutectic reaction in an Al-Cu binary system (partition coefficient, kCuS/L < 1) and forms (Al,Cu)6Fe phase in an Al-Fe-Cu ternary system. In contrast, Ti element exhibits a peritectic reaction in an Al-Ti binary system (partition coefficient, kTiS/L > 1) and independently forms the Al3Ti phase (no partitioning into the Al6Fe phase). Herein, we designed two ternary alloy compositions of Al–2.5Fe–2Cu and Al–2.5Fe–1.5Ti (mass%) available to the L-PBF process utilizing thermodynamic calculations. In this talk, the microstructure of the L-PBF processed ternary alloys will be presented and discussed in terms of Cu or Ti elemental distribution.
CVMin-Seok Kim Gachon University Optimization of simulation models for continuous casting processes of aluminum alloys AbstractOptimization of simulation models for continuous casting processes of aluminum alloys
The traditional direct-chill casting process has been widely used for manufacturing aluminum slabs or billets. Additionally, the twin-roll casting process has gained significant attention as a method for producing aluminum sheets. Recently, with the expanded application of aluminum alloys in transportation vehicles, there is a growing demand for the production of high-strength aluminum ingots. Most of these high-strength aluminum alloys have a wide solidification temperature range, requiring sophisticated process control technologies to control casting defects during the continuous casting. Trial-and-error methods in the mass production line have limitations in terms of cost and productivity. Therefore, to minimize costs and enhance the quality of ingots, the application of process simulation technology is essential. In this study, simulation models for the direct-chill casting and twin-roll casting processes are developed, and methods for optimizing them for practical application are introduced. By applying temperature distribution measurements using thermocouples in actual continuous casting processes to the simulation model, optimization was carried out. The results showed that the simulation model effectively predicted the temperature distribution and solidification behavior of actual continuous processes.
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VII. Computational Materials Science
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Keynote Speakers
Kyeongjae Cho
University of Texas at DallasInterlayer Design of Heterostructure Thermal Boundary Resistance
AbstractInterlayer Design of Heterostructure Thermal Boundary Resistance
The performance of GaN power device is limited by the capacity of waste heat removal at the device level to avoid thermally activated device degradation mechanisms at the device hot spots. Specifically, the thermal resistance along the heat transport pathway from the GaN device hot spots to an adjacent heat spreader (e.g., diamond or AlN) is dominated by the thermal boundary resistance (TBR) of the heterostructure interfaces. To enable the potential performance of GaN power devices, it is critically important to optimize the GaN/diamond TBR well below the previously reported values which are larger than the classically limit of ~3 m2K/GW from the diffuse mismatch model (DMM) study of phonon transport at the heterostructure interfaces. In this talk, we will discuss the role of nanoscale interlayers at the heterostructure interfaces and demonstrate that the interlayer phonon engineering can enable novel phonon transport mechanisms at nanoscale leading to TBR values lower that the classical DMM limit.
This work was supported by DARPA Sponsored Special Projects (DSSP) in 2021 and 2022, and is currently supported by DARPA Technologies for Heat Removal in Electronics at the Device Scale (HTREADS) program.CVInvited Speakers
Name Affiliation Title Abstract CV Sang Soo Han KIST TBD CVChiho Kim Georgia Institute of Technology / Matmerize, Inc. Machine learning-aided design of biodegradable polymers AbstractMachine learning-aided design of biodegradable polymers
In pursuing sustainable materials, biodegradable polymers have emerged as promising alternatives to traditional plastics, finding applications across diverse industries. Particularly, the degradation products of conventional plastic are of specific concern, and fully biodegradable and non-toxic plastic alternatives offer promising solutions to this ongoing challenge. However, a rational design approach to engineer biopolymers for degradation after their intended use remains elusive. This is largely due to our inability to understand and model performance metrics (such as weight loss over time) capturing the degradation behavior of these materials as a function of chemical, geometric, and environmental factors. As an exciting development in this direction, we have established predictive machine learning models that utilize physics-informed deep neural networks (NN) on previously established, manually curated experimental data that characterizes the weight loss behavior of fully biodegradable polyester copolymer samples in both water and soil natural environments. The models were applied in a series of experiments to predict the mass loss of approximately 10,000 structural and compositional variations of the 230 homo- and copolymers originally included in the original training set. The predicted mass loss for these candidate biodegradable polymers over 365 days allowed us to identify novel copolymers with the potential to replace existing chemistries while matching property values to the desired performance metric ranges. This talk will discuss our findings and future directions, including the integration of critical properties, such as thermal and mechanical characteristics, into the screening and design workflow, bringing us one step closer to realizing the grand vision of a sustainable circular plastic economy.
CVHyeyoung Shin Chungnam National University Enhancing Oxygen Evolution Reaction Efficiency: Insights from Quantum Mechanics Calculations AbstractEnhancing Oxygen Evolution Reaction Efficiency: Insights from Quantum Mechanics Calculations
Electrochemical water splitting, powered by solar-generated electrical energy to produce hydrogen and oxygen molecules, serves as a cornerstone for advancing sustainable and clean energy. However, the efficiency and electro-kinetics of hydrogen production face challenges due to the complex four-electron-proton coupling required for the oxygen evolution reaction (OER). Despite extensive efforts to improve the catalytic performance of OER electrocatalysts, the overpotential required remains too high for cost-effective hydrogen production. Through quantum mechanics calculations, we investigate the OER mechanism on nickel oxyhydroxide-based catalysts, identifying the stabilization of the radical character on the oxygen of the metal-oxyl bond as a key factor for enhancing OER. Subsequent tests on a variety of metal-doped nickel oxyhydroxide electrocatalysts confirm our theoretical findings, establishing a significant correlation between OER activity and the electronic configuration of the doped transition metal ions, as well as the in situ conductivity of the electrocatalysts. This research provides a solid foundation for designing more efficient OER catalysts, offering valuable insights into their development.
CVHan Seul Kim Chungbuk National University Computational insights into novel low-dimensional materials for next-generation semiconductor applications AbstractComputational insights into novel low-dimensional materials for next-generation semiconductor applications
Low-dimensional materials such as two-dimensional materials, novel metal-halide crystals with internal low-dimensional polyhedrons, and colloidal quantum dots attract great attention due to their exceptional tunability of electrical and optical properties. These materials are expected to be important building blocks in the development of next-generation semiconductor devices. In this presentation, several computational studies based on density functional theory (DFT) will be introduced for the application of low-dimensional materials to various functional semiconductor devices. In particular, it will be highlighted that the material engineering parameters revealed by electronic structure calculations can act as key components toward seamless collaborations with experiments.
References
[1] Nano Today 55, 102184 (2024)
[2] Adv. Funct. Mater. 32, 2202207 (2022)CV
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VIII. Advanced Materials Imaging Technique
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Keynote Speakers
Invited Speakers
Name Affiliation Title Abstract CV Se-ho Kim Korea University Hydrogen imaging using Atom Probe Tomography (Hi-APT) AbstractHydrogen imaging using Atom Probe Tomography (Hi-APT)
Hydrogen may result a ubiquitous influence on the properties of various materials, yet its quantitative assessment remains a challenge in microscopy and microanalysis. Recent advancements in atom probe could offer promising detection sensitivity and could evaluate the structural and functional impacts of hydrogen. However, hurdles persist in specimen preparation and handling. This has spurred innovative developments in methodology and instrumentation and enable comprehensive understanding of hydrogen's effects on material properties. In this presentation, I will briefly introduce cryogenic atom probe and discuss preliminary results and the outcomes.
CVSeong Heon Kim Jeonbuk National University Nanoscale Study on Lithium-Ion Battery Electrodes Using Scanning Probe Microscopy Techniques AbstractNanoscale Study on Lithium-Ion Battery Electrodes Using Scanning Probe Microscopy Techniques
The demand for high-performance lithium-ion batteries (LIBs) is significant in various energy-related fields, including electric vehicles and energy storage systems (ESSs). To develop high-performance LIBs, it is essential to understand the degradation phenomena of LIB electrodes. Recently, several scanning probe microscopy (SPM) techniques have been introduced to study LIB electrode materials. The application of these new analysis tools to the LIB research field enables us to observe what happens inside the LIB electrode materials at the nanoscale.
In this talk, I will present research results based on SPM techniques such as scanning spreading resistance microscopy (SSRM) and Kelvin probe force microscopy (KPFM) used to investigate the degradation of LIB cathode and anode materials. [1-5].
[1] S.Y. Park et al. Nano Energy 49, 1–6 (2018).
[2] S.H. Kim et al. ACS Appl. Mater. Interfaces, 10, 24549−24553 (2018).
[3] S.H. Kim et al. Journal of Power Sources 407, 1–5 (2018).
[4] S. Choi et al. Journal of Alloys and Compounds 943, 169029 (2023)
[5] M. Cho et al. Journal of Alloys and Compounds 963, 171215 (2023)CVSeung-Ho Yu Korea University Analysis and Design of Electrode Materials for Li Rechargeable Batteries AbstractAnalysis and Design of Electrode Materials for Li Rechargeable Batteries
Lithium-ion batteries (LIBs) have long been the go-to energy storage solution for portable electronics and electric vehicles. Despite their widespread use, LIBs struggle to keep up with increasing demands for higher energy density as technology progresses. Thus, there's an urgent call to develop alternative battery systems to supplant LIBs. The intricate nature of reaction mechanisms in most post-Li-ion battery systems only underscores this challenge. Therefore, gaining a thorough understanding of how these systems function during charge and discharge cycles is imperative for their advancement.
This presentation will focus specifically on investigating the reaction mechanisms of post-Li-ion batteries through operando imaging. For instance, there has been considerable interest in exploring Li anodes due to their high theoretical specific capacities. However, the complexity of the reaction mechanism adds a layer of challenge that is not yet fully understood. Utilizing operando X-ray microscopy enables the observation of the morphological evolution of post-Li-ion battery electrodes while the battery is in operation. By directly observing changes in electrode materials during battery operation, we can gain new insights into comprehending the complexities of the reaction mechanism.CVHyobin Yoo Sogang University Operando TEM investigation of polar domain dynamics in 2D sliding ferroelectrics AbstractOperando TEM investigation of polar domain dynamics in 2D sliding ferroelectrics
Control of interlayer stacking angle in two-dimensional (2-D) van der Waals (vdW) heterostructure enables one to engineer the crystal symmetry to imprint novel functionality. By stacking two layers of transition metal dichalcogenides (TMD) with designed twist angle, one can break the inversion symmetry and thereby develop vertical electric polarization. The direction of the electric polarization can be switched electrically, suggesting that the twisted bilayer TMD can host ferroelectricity. Such ferroelectricity reported in twisted bilayer vdW system is distinguished from conventional ferroelectrics in that the lateral sliding of the constituent layers induces vertical electric polarizations.
Here we employ operando transmission electron microscopy (TEM) to investigate the domain dynamics in 2-D vdW sliding ferroelectrics. Operando TEM technique enables one to examine the structural change in the environment that mimics the electrical device operating condition. We find the domain dynamics in response to vertical electric fields is governed by the consecutive domain wall pinning-depinning process as noted by Barkhausen noises in the polarization hysteresis loop[1]. Moreover, exploiting stroboscopic operando TEM on the vdW ferroelectrics, we directly measured the domain wall velocity which is found to be limited by various disorders present in the specimens[1]. Aberration corrected scanning transmission electron microscopy analysis identifies the microstructural origin for the domain wall pinning, providing structural insight on how to improve the switching speed of the sliding ferroelectrics.
[1] K. Ko et al., Operando electron microscopy investigation of polar domain dynamics in twisted van der Waals homobilayers, Nat. Mater. 22, 992 (2023)CVJi Hye Lee Advanced Institute of Convergence Technology Flexoelectricity-driven mechanical ferroelectric polarization switching in metastable ferroelectrics AbstractFlexoelectricity-driven mechanical ferroelectric polarization switching in metastable ferroelectrics
Recently, an intriguing new concept based on flexoelectricity has emerged, ultilizing mechanical forces to switch ferroelectric polarization. This so-called mechanical switching of polarization could be technologically advantageous over conventional switching of polarization via an external electrical bias. First of all, it offers the potential to mitigate side effects induced by electric bias, such as charge injection, Joule heating, and dielectric breakdown. In addition, it might potentially enable much higher-density data writing, compared to conventional electrical bias-driven polarization switching. In this presentation, we present a breakthrough finding of hyper-efficient mechanical polarization switching in metastable ferroelectrics, marking a significant advancement in overcoming prior challenges. Through a combination of density functional theory, phenomenological modeling, and comprehensive electrical and mechanical characterizations, we unveil the remarkably superior mechanical switching of polarization exhibited by an artificial metastable ferroelectric CaTiO3 film, compared to other conventional ferroelectrics.
CVJoon Ha Chang RIST Investigating Structural and Chemical Characteristics of Lithium-Ion Battery Materials Using Electron Microscopy Techniques AbstractInvestigating Structural and Chemical Characteristics of Lithium-Ion Battery Materials Using Electron Microscopy Techniques
Over past years, the lithium-ion battery (LIB) market has undergone significant growth, prompting the need for advancements in the materials used in battery components. Among these components, the development of cathode and anode materials is crucial for enhancing the energy density and durability of battery cells. Additionally, there is growing interest in the development of solid electrolytes for the realization of all-solid-state batteries. These batteries offer enhanced safety by preventing thermal runaway and increased energy density by eliminating unnecessary components used in liquid electrolytes.
Electron microscopy (EM) is a powerful tool for analyzing the microstructure and chemical composition of materials, ranging from the microscale to the nanoscale. This technique provides comprehensive insights into materials used in LIB applications. It plays a crucial role for obtaining in-depth understanding of cathode, anode, and solid electrolyte materials.
In this presentation, we discuss the current trends in the development of cathode, anode, and solid electrolyte materials. Additionally, we highlight the importance of EM imaging studies in characterizing the structural and chemical properties of these materials. This emphasizes the significant role of EM techniques in assessing the impact of material properties on advanced LIB technology.CVJanghyun Jo Research Centre Juelich TBD Yifei Yuan Wenzhou university TBD
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IX. Semiconductor Thin Films, Materials and Devices
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Keynote Speakers
Rong Chen
Huazhong University of Science and TechnologyThin film atomic layer deposition and selective processes
AbstractThin film atomic layer deposition and selective processes
In the past decades, Moore’s law drives the semiconductor industry to continuously shrink the critical size of transistors. However, the current fabrication processing is causing challenges toward future downscaling, especially for the complex stacking and 3D structures. Atomic layer deposition provides high accuracy with nanometer or close-to-atomic scale to fabricate nanostructures. In this talk, the thin films fabrication via atomic layer deposition is presented, including selective deposition process and films with different properties. Selective ALD process enabling depositing atoms at desired surface locations. Through embedding selective atomic layer deposition into patterned substrates, vertical angstrom resolution can be achieved as well as lateral resolution. The downscaling of transistors drives the selective deposition of dielectrics and metals for alignment. Various template-assisted selective deposition methods, e.g. self-assembled monolayers, have been utilized for the alignment of 3D complex structures. Furthermore, the inherent selective deposition depends on initial nucleation control rather than relying on introducing surface modification steps will be presented. The fundamental mechanism lies in tuning the chemical thermodynamic and kinetic differences. Thin films with different properties are important for various functions. Low k value films are fabricated for ILD in ICs devices to form binary oxides as well as in situ conversion of ALD film to MOF structures. Functional oxides such as SnO, IGZO are studied with process tuning to obtain high mobility, etc. Encapsulations via oxides for optoelectronics and optics are also studied. These bottom-up approaches may provide ultimate solutions to achieve advanced technology nodes. Thus, the atomic layer deposition enables integrated manufacturing of nanomaterials, nanostructures, nanodevices and nano-systems with high accuracy to extend Moore’s law in semiconductor and emerging fields.
CV
Ang Diing Shenp
Nanyang Technological UniversityChalcogenide based Conductive Bridge Resistive Device for Universal Storage Memory – Opportunities and Challenges
AbstractChalcogenide based Conductive Bridge Resistive Device for Universal Storage Memory – Opportunities and Challenges
The rapid growth of Internet-of-Things cum Artificial Intelligence applications has created an urgent and strong demand for a new storage class memory that can address the shortcomings of current mainstream memory technologies, namely DRAM and Flash memory, developed several decades ago. Because DRAM is volatile and its capacity is limited by cost, data must be frequently transferred to and from the non-volatile Flash memory. While the latter is relatively inexpensive and has a large capacity, it is much slower by about 105-106 times. This large speed difference is a major challenge for data center applications.
Therefore, new memory devices are currently being developed to address the above challenge. To be able to address the DRAM-Flash latency gap, or eventually replacing both as a universal memory, the new memory device must be non-volatile, has a program speed and voltage comparable to DRAM (10 ns, 1 V) and a memory density comparable to Flash memory (>10 Gb/mm2). Among the emerging memory devices, the resistive random access memory or ReRAM device stands out as a promising candidate capable of fulfilling these requirements. However, two major obstacles must be overcome, namely performance variability and the lack of a suitable selector that can enable 3D integration.
In this talk, I will summarize the current progress of our research on silver-gated chalcogenide conductive bridge resistive memory devices and show that these devices have good prospects in overcoming the abovementioned challenges. Key characteristics include highly uniform switching behavior and ultralow DC switching voltages (which can facilitate 1 V pulsed switching with a low program/erase latency of ~30 ns). In addition, stack engineering may allow one to achieve volatile switching at milliampere current level, enabling a similar device to be deployed as a selector, providing compact integration with the memory counterpart.CVInvited Speakers
Name Affiliation Title Abstract CV Gun Hwan Kim Yonsei University TBD Jeong Hwan Han Seoul National University of Science & Technology Atomic Layer Deposition of Molybdenum-based Electrode Films for MIM and MFM Cell Capacitor Applications AbstractAtomic Layer Deposition of Molybdenum-based Electrode Films for MIM and MFM Cell Capacitor Applications
As the miniaturization of metal-insulator-metal (MIM) and metal-ferroelectric-metal (MFM) cell capacitors advances, there's a growing need for novel electrode materials possessing low resistivity, high work function, and exceptional mechanical properties. Molybdenum (Mo)-based conducting films, such as MoNx and MoO2, are gaining attention as next-generation electrodes to replace conventional TiN films due to their excellent properties, including elevated work function (>5 eV) and high mechanical strength. In this presentation, we will report on the atomic layer deposition (ALD) of various Mo-based films, including MoNx and MoO2, for next-generation MIM and MFM cell capacitor applications. Firstly, conductive MoNx films were grown by ALD, and MIM and MFM capacitors were constructed using a MoNx layer in combination with HfZrOx (HZO) films. Despite the excellent electrical properties of the PEALD Mo2N films, severe interfacial reactions between MoNx and HZO occurred. A bilayer electrode structure comprising ALD TiN and Mo2N was introduced to effectively regulate the interfacial reaction, aiming to enhance both the interface property and electrical performance of the capacitors. Secondly, a new strategy to grow monoclinic MoO2 films by ALD was investigated. It was found that the metastable MoO2 phase was stabilized by SnOx doping in MoOx thanks to the template effect between SnO2 and MoO2. ALD TiO2 films grown on Sn-doped MoO2 electrodes demonstrated remarkably high dielectric constants of 100–136, indicating that rutile structure TiO2 was grown. These findings indicate that ALD Sn-doped MoO2 films are promising electrodes for use in TiO2 based MIM capacitor.
CVWoongkyu Lee Soongsil University TBD CVHong-Sub Lee Kyung Hee University Alkali Ion-Based Memristors for Neuromorphic Computing Applications AbstractAlkali Ion-Based Memristors for Neuromorphic Computing Applications
Nanoscale memristive systems are emerging as an alternative platform to conventional silicon transistors for energy-efficient hardware implementation of neuromorphic computing. The memristor (ionic memristor) is referred to as the fourth circuit element, which the resistance can be changed gradually by the electric pulse signals that have been applied to it. Moreover, the stored resistance state in a memristor is non-volatile, and their large on/off ratio with analog resistive memory characteristics makes this system appealing as a circuit element for neuromorphic computing devices. Their gradual resistance change characteristics induced by ion migration depend on the magnitude, duration, and number of programming pulses, with the resulting synaptic response mimicking the synaptic function of biological neurons. However, the stochastic nature of defect-induced switching coupled with limited control over intrinsic materials defects have been identified as the primary factors undermining the reliability of memristors in scaled crossbar-array architecture.
In this talk, I will present a Na-doped TiO2 memristor that uses high-mobility sodium cations instead of oxygen anions (oxygen vacancies) as the main agent for resistive switching. In this manner, reversible switching is achieved even under rectifying characteristics involving more than three orders of magnitude smaller current than a forward-biased memristor. We adopted TiO2 as the matrix material since it can be controllably grown by atomic layer deposition (ALD) and acts as an effective host for Na-ion migration. Therefore, unlike conventional memristors based on oxygen anions, the high mobility of Na ions can be expected to produce memristive behavior regardless of the underlying oxygen vacancy concentration and even under a low electrical current.
ACKNOWLEDGMENTS
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (grant No. NRF-2022R1C1C1006337 and NRF- 2022M3F3A2A01044952).CVKiyoung Lee Hongik University TBD So-Yeon Lee Kumoh National Institute of Technology Characterization of microstructures of metal thin film for flexible electronics based on TKD and ASTAR AbstractCharacterization of microstructures of metal thin film for flexible electronics based on TKD and ASTAR
Nanostructure of cupper thin film on polyimide flexible substrate is revealed by novel orientation imaging techniques. Copper and polyimide thicknesses play critical roles on what technique is successful in acquiring diffraction patterns while avoiding electron beam damage and blistering. Conventional electron back-scattered diffraction as well as emerging higher resolution transmission orientation imaging were employed to resolve the grain structure. Spatial resolution is compared in terms of minimum detectable twin width. Experiments and simulations indicate that polyimide thicknesses below 1000 nm allow the electrons to scape; resulting in acceptable reflective or transmission patterns and lack of blistering.
CVSung Hun Jin Incheon National University TBD Takashi Onaya The University of Tokyo Design of Interface Formation Process of Ferroelectric-HfxZr1−xO2/TiN Interface for Metal–Ferroelectric–Metal Capacitors with High Fatigue Resistance AbstractDesign of Interface Formation Process of Ferroelectric-HfxZr1−xO2/TiN Interface for Metal–Ferroelectric–Metal Capacitors with High Fatigue Resistance
Ferroelectric HfxZr1−xO2 (HZO) is attractive for future non-volatile memory devices due to its scalability and excellent CMOS compatibility. The fatigue is one of the most serious issues in practical applications. The oxygen vacancies (VO) in HZO films formed during field cycling are thought to cause domain pinning, resulted in fatigue [1]. However, it has been unclear why VO increases in HZO films. In this work, we studied reaction at HZO/TiN interfaces of TiN/HZO/TiN metal–ferroelectric–metal (MFM) capacitors during field cycling to clarify the origin of VO formation. We also demonstrated superior fatigue properties by designing HZO/TiN interface formation processes.
HZO/TiN interfaces were characterized using synchrotron hard X-ray photoelectron spectroscopy after applying switching cycles. The Ti-O peak intensity of Ti 1s spectra increased during fatigue field cycling while no difference of Ti 1s spectra was observed between the pristine and wake-up states. Therefore, the surface oxidation of TiN electrodes occurred in the fatigue state, indicating that oxygen atoms were supplied from the HZO film to TiN electrodes. Thus, we concluded that one of the origins of additional VO formation in HZO films should be reaction at HZO/TiN interfaces during field cycling.
Based on these results, we focused on controlling oxygen atom movement at HZO/TiN interfaces during field cycling to obtain superior fatigue properties. We will discuss demonstration of MFM capacitors with high fatigue resistance by introducing a surface-oxidized TiN bottom-electrode [2] and inserting ZrO2 nucleation layers between the HZO film and TiN electrodes [3,4] to prevent the unwanted reaction at HZO/TiN interfaces.
[1] M. Pešić et al., Adv. Funct. Mater. 26, 4601 (2016).
[2] T. Onaya et al., Solid-State Electron. 210, 108801 (2023).
[3] T. Onaya et al., APL Mater. 7, 061107 (2019).
[4] T. Onaya, ECS Trans. 112, 75 (2023).CVYounghwan Lee Chonnam National University A study on the structural and electrical properties of ferroelectric Hf0.5Zr0.5O2 thin films fabricated under vacuum condition AbstractA study on the structural and electrical properties of ferroelectric Hf0.5Zr0.5O2 thin films fabricated under vacuum condition
HfO2-based metal-ferroelectric-metal (MFM) capacitors have attracted increased interest from the ferroelectrics community and the semiconductor industry due to their ability to exhibit ferroelectricity at nanometer length scales. In order to expedite the practical use of HfO2-based MFM capacitors including ferroelectric field effect transistor, several performance metrics need to be considered in aspects of reliability: uniformity, scalability, endurance, program write/erase speed, retention, etc. The performance of ferroelectric HfO2-based MFM capacitors generally depends on various factors such as surface energy (e.g., through grain size or thickness), defects (e.g., through dopants, oxygen vacancies, or impurities), electrodes, interface quality, and preferred crystallographic orientation (also known as crystallographic texture, or simply texture) of grains and/or domains. Importantly, it should be noted that an interfacial layer (IL) is inevitably created when dissimilar materials are adjacent and the IL between ferroelectric/electrode in MFM capacitors often deteriorates the measured electrical properties. To improve reliability performance of the HfO2-based MFM capacitors, thus, the IL should be avoided in the capacitor stack.
In this study, we fabricated MFM capacitors of TiN/Hf0.5Zr0.5O2 (HZO)/TiN via Atomic Layer Deposition (ALD) without breaking vacuum to avoid IL formation, named as Sequential, No-Atmosphere Processing (SNAP). Specific design of the unconventional SNAP recipe and its effect on structural and electrical properties of the HZO-MFM capacitors is systematically studied here. Hence, we demonstrate the ability to control crystallographic texture of the HZO by using different texture of TiN during the SNAP deposition. Our results will provide new insight on the importance of the vacuum processing as well as the effect of textureCV
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X. Emerging Materials and Devices in Advanced Biomedical Application
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Keynote Speakers
Ji Hoon Jeong
Sungkyunkwan Univ.Microneedle-Mediated Chemoimmunological Intervention of Crosstalk between Tumor and Lymph Node for Improved Cancer Immunotherapy
AbstractMicroneedle-Mediated Chemoimmunological Intervention of Crosstalk between Tumor and Lymph Node for Improved Cancer Immunotherapy
Tumor-draining lymph node (TDLN) is the primary site in which tumor-driven antigens are presented to the immune cells. It facilitates the activation of T cells and other immune cells, which can then migrate to the tumor site to elicit anti-tumor effects. However, tumors can also exploit the TDLN to render immune suppressive microenvironment favorable for the migration of tumor cells from the primary tumor site. The TDLN serves as a niche for metastatic tumor cells to survive and proliferate before they spread to distant organs. Herein, we develop amphiphilic tri-block copolymer-based dissolving microneedles (dMN) that generate self-assembled nanomicelles (NMCs) upon their dissolution after cutaneous application, which enable the drug encapsulation in NMCs and their subsequent migration to the TDLN. The dMN was employed for the delivery of SKKU-06, a natural pleiotropic immune modulator derived from fungi, which exhibits both anti-cancer and immunomodulatory properties in melanoma. The dMN-assisted intradermal administration of SKKU-06 to the melanoma site achieved enhanced anticancer effects, including immunogenic cancer cell death, enhanced the activation and maturation of antigen-presenting cells (APCs), and stimulated CD8+ T cell proliferation within both the tumor and TDLN. Notably, SKKU-06@dMN shifted the tumor microenvironment (TME) from immune suppressive (cold) to inflammatory (hot), which was further evidenced by combining it with anti-PD-1 treatment. This combined treatment significantly decreased Treg populations, altered macrophage polarization (increasing the M1/M2 ratio), and improved intratumoral infiltration CD8+ T cells, leading to the efficient growth inhibition of established primary and metastatic melanoma and increased overall survival of tumor-bearing animals.
CVInvited Speakers
Name Affiliation Title Abstract CV Dong Yun Lee Hanyang University Aurozyme : A Revolutionary Nanozyme in Colitis, Switching Peroxidase-like to Catalase-like Activity AbstractAurozyme : A Revolutionary Nanozyme in Colitis, Switching Peroxidase-like to Catalase-like Activity
Inflammatory bowel disease (IBD) is a refractory disease instigated by several factors such as disrupted intestinal barrier functions, elevated levels of reactive oxygen/nitrogen species (ROS/RNS), and high-mobility group box 1 (HMGB1) because these hazard signals dysregulate mucosal immune responses, which triggers the severity of colitis. Aurozyme, a novel nanomedicine composed of gold nanoparticles (AuNPs) and glycyrrhizin (GL) with a glycol chitosan coating layer, represents a promising therapeutic approach for colitis of multiple etiologies. It effectively scavenges reactive oxygen/reactive nitrogen species (ROS/RNS) and damage-associated molecular patterns (DAMPs), neutralizing hazardous signals involved in colitis. Aurozyme’s unique ability to switch the harmful peroxidase-like activity of AuNPs to beneficial catalase-like activity enables it to promote sustained anti-inflammatory effects, restore intestinal function, and increase the abundance and diversity of beneficial probiotics essential for gut microbial homeostasis. To our knowledge, this is the first biocompatible instance to switch peroxidase-like activities to catalase-like activities using AuNPs. Collectively, our findings suggested that mucoadhesive gold nanoparticles could be used as a potential therapeutic for IBD treatment.
CVDonghee Son Sungkyunkwan Univ. Stable Tissue-interfacing Self-healing Bioelectronics AbstractStable Tissue-interfacing Self-healing Bioelectronics
Conventional flexible/stretchable devices capable of monitoring bio-signals and delivering the feedback information have been considered as essential functional components in realizing the stable closed-loop bioelectronics. Despite such significant progress, their mechanical and electrical instability, originating from materials fatigue and the absence of tissue adhesion, still remains a challenge in pursuit of strain-durable tissue-interfacing capability.
Here, we report optimal stretchable materials design strategies and device fabrication/integration technologies for the two different kinds of self-healing tissue-adhesive bioelectronics: i) A patch-type platform for either facile peripheral nerve repair (neurorrhaphy) in rodents and nonhuman primates or large-scale conformal cardiac interfacing; ii) A syringe-injection-type platform for instantaneous closed-loop rehabilitation. The patch-type self-healing bioelectronics consists of ionically conductive hydrogel adhesive and tough composite electrodes with solid and liquid micro-/nano-fillers, enabling both on-tissue strain-insensitive electrical performance and mechanical adaptation. In terms of the injectable type, tough hydrogel with irreversible yet freely rearrangeable biphenyl bonds and reversible coordinate bonds with conductive gold nanoparticles was applied to injured nerves/muscles for realizing immediate closed-loop robot-assisted rehabilitation and effective tissue regeneration.CVYoun Soo Kim POSTECH Biomimetic hydrogels for bioelectronics AbstractBiomimetic hydrogels for bioelectronics
As a new class of materials, implantable flexible electrical conductors have recently been developed and applied to bioelectronics. An ideal electrical conductor requires high conductivity, tissue-like mechanical properties, low toxicity, reliable adhesion to biological tissues, and the ability to maintain its shape in wet physiological environments. Herein, a facile method for manufacturing a new conductive hydrogel through the simultaneous exfoliation of graphite and polymerization of zwitterionic monomers triggered by microwave irradiation is introduced. The mechanical properties of the obtained conductive hydrogel are similar to those of living tissue, which is ideal as a bionic adhesive for minimizing contact damage due to mechanical mismatches between hard electronics and soft tissues. Furthermore, it exhibits excellent adhesion performance, electrical conductivity, non- swelling, and high conformability in water. This hydrogel has demonstrated tissue-like extraneuronal electrodes, which improve the tissue-electronic interfaces, promising next-generation bioelectronics applications.
CVJinho Kim Stevens Institute of Technology TBD Kyung Min Park Incheon National University Bioactive Polymeric Hydrogels for In-Situ Tissue Regeneration AbstractBioactive Polymeric Hydrogels for In-Situ Tissue Regeneration
Polymeric hydrogels have attracted substantial attention as promising materials for tissue engineering and regenerative medicine due to their tunable properties and structural similarity to the natural extracellular matrices. An emerging paradigm in designing advanced hydrogels is to create bioactive matrices promoting endogenous tissue regeneration via host tissue stimulation by physicochemical cues of the hydrogel materials. This presentation discusses how the hydrogels are designed to create bioactive matrices that can recapitulate or stimulate native tissues to facilitate endogenous tissue regeneration. Specifically, we focus on introducing bioactive hydrogels releasing molecular oxygen or therapeutic ions for enhanced wound healing and tissue regeneration.
CVHyeon Yu Kim Northeastern University TBD Xiyu Li Sichuan University Nano biomaterials for hard tissue regeneration and multimodal tracing AbstractNano biomaterials for hard tissue regeneration and multimodal tracing
Background
Dentistry still faces numerous scientific challenges, including insufficient early bone formation and suboptimal osseointegration of implants, and susceptibility to bacterial infections. Also, the current restorative materials used in clinical dentistry lack the capability of multimodal tracing, which hinders effective tracking of the implanted material or its degradation, and bone/tooth repair processes, as well as limits comprehensive and accurate reconstruction information acquisition. In light of these limitations, we proposed a novel approach that combines the improvement of restorative properties in implant materials with the integration of multimodal tracing capabilities.
Methods
We employed rare earth ions (Yb/Ho), antibacterial ions (Zn), and paramagnetic ions (Fe) to prepare various nano hydroxyapatite (HA) crystals with multimodal tracing properties. These crystals can exhibit fluorescence, CT, and MRI tracing characteristics. Additionally, we designed and fabricated a groundbreaking titanium dental implant (magnet@Ti) with a localized static magnetic field, which promotes early osteogenesis and osseointegration with the synergistic effect of superparamagnetic HYH-Fe nanocrystals. Furthermore, we developed a composite bone scaffold containing HYH-Zn nanocrystals with pro-osteogenic, anti-infective, and traceable functions. We also used the uniform HA-Tb nanocrystals to elucidate the mechanism of interaction of HA nanocrystals in osteoblasts and new bone tissues.
Conclusions
By endowing implant materials with multimodal tracing capabilities, our approach harnesses the advantages of various imaging modalities, enabling precise tracking of in vivo material changes, evaluation of tissue reconstruction and repair, exploration of material-cell/tissue interactions, and enhanced understanding of tissue regeneration mechanisms. This achievement further facilitates micro-level regulation in the biological processes of bone regeneration.CV
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XI. Energy Harvesting Materials and Devices for Self-powered Electronics
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Keynote Speakers
Haixia Zhang
Peking UniversityHigh performance active smart sensors and their applications
AbstractHigh performance active smart sensors and their applications
The field of stretchable electronics has been developed rapidly in recent years due to their potential importance in diverse fields. Although the development of functional materials and flexible microsystems has been significantly advanced over the past decade, the precise control of soft structures remains a major challenge for practical applications of energy harvesting, functional sensing and interaction. Magnetic material is an attractive candidate that enables multifunctional devices with capabilities in both sensing and actuation.
In this talk, we show that magnetic materials with temporary magnetization can also achieve programmable, multimodal locomotion through a set of judiciously engineered 3D designs. Such 3D soft structures can exhibit various tethered locomotion under the precise control of magnetic fields, including local deformation, unidirectional tilting and omnidirectional rotation. Applications will focus on energy harvesting systems, including a 3D piezoelectric device for non-contact conversion of mechanical energy and active motion sensing, as well as a 3D magnetic-controlled solar cell that automatically tracks the light through continuous and accurate rotation. The design strategy and resulting magnetic-controlled 3D soft structures hold great promise not only for enhanced energy harvesting, but also for multimodal sensing, robotic interfaces, and biomedical devices through further encapsulation.CVInvited Speakers
Name Affiliation Title Abstract CV Isaku Kanno Kobe University Piezoelectric Thin Films for a Micro-Power Source AbstractPiezoelectric Thin Films for a Micro-Power Source
Recently, piezoelectric electromechanical systems (MEMS) using piezoelectric thin films have been actively investigated as next-generation functional microdevices [1]. Vibration energy harvesting is one of the promising applications in piezoelectric MEMS because piezoelectric thin films are able to generate relatively large electric power even with simple micro- or millimeter-scale unimorph cantilevers. For practical application of piezoelectric energy harvesters, piezoelectric thin films are required to have not only large piezoelectric properties but also sufficient long-term stability, high fracture toughness, and flexibility. Our group has developed piezoelectric PZT thin films deposited on metal foils to satisfy the above requirements [2]. Among various metal foils, stainless steel is the most suitable because thin stainless steel foils can be easily obtained at low cost. In this study, we deposited PZT thin films on stainless steel foils with a thickness of less than 50 μm by rf-magnetron sputtering method and used them for intentional bending power generation. We fabricated finger-flexion PZT thin-film power generators and succeeded in lighting an LED by the generating electric power [3]. In addition, card-bending-type PZT thin film power generators were fabricated and successfully generated a large electric power of 177 μW [4].
[1] I. Kanno, Jpn. J. Appl. Phys., 57 (2018) 040101
[2] H. Hida, et al., Microsyst. Technol., 22 (2016) 1429-1436
[3] R. Harada, et al. , Sens. Actuators A, 322 (2021) 112617
[4] D. Teramoto, et al., Sensors and Materials, to be publishedWonjoon Choi Korea University Ultrafast extreme thermal-chemical-electrical waves for fabricating multi-material/interface structures toward energy harvesting and storage devices AbstractUltrafast extreme thermal-chemical-electrical waves for fabricating multi-material/interface structures toward energy harvesting and storage devices
Rationally designed multi-element/interface materials (M-EIM) enable precise control of physicochemical properties, improving energy conversion. Among them, hybridizing multi-metal(or semiconductor)/metal oxides and carbon-based materials (MMO-CBM) have emerged as an effective strategy for boosting energy harvesting/storage performances because a combinatorial approach to low-dimensional materials can provide an unusual electrochemical characteristics which are not exhibited by single-element materials. However, their conventional synthesis inevitably involves phase/interface segregation, and requires complex procedures involving high costs and long processing times. Here, we introduce ultrafast extreme thermal-chemical-electrical waves (UTEW) as a tunable-scalable fabrication technique of MMO-CBM toward high-performance energy harvesting and storage devices. UTEW is an instant thermal-electrical-chemical conversion that induces thermochemical reactions among precursor mixtures, implementing unusual thermodynamic decomposition and recombination for fabricating engineered M-EIM. It is capable of supplying tremendous thermochemical pulse waves through entire precursor mixtures within a few milliseconds to seconds, while the overall temperature ranges and heating-cooling rates are controllable by tuning processing parameters. We present recent researches utilizing UTEW for advancing energy harvesting/storage materials. An electrothermally tunable morphological and redox design of heterogeneous Pd/PdxOy/carbon is devised to develop humidity-driven energy harvesters. Then, we report a humidity-thermoelectric bimodal energy harvester for sustainable and complementary power generation, overcoming thermal saturation or the temporal absence of thermal gradient in thermoelectricity and the low power output in humidity-driven energy harvesting. Furthermore, UTEW-driven fabrication strategies are extended to bi-, tri-, and high-entropy metal oxides involving unique structures for energy storage devices. Morphological/structural traps capturing metastable states and wetted interfaces of the constituents are demonstrated through the unconventional combination/arrangement of materials, thereby completing facile fabrication of hybrids that do not previously exist. The UTEW-based design strategy will inspire extremely rapid, yet precisely controlled fabrication routes to sorting and optimizing heterogeneous materials for energy harvesters, electrochemical cells, catalysts, electromagnetic shielding, and sensors, potentially useful in self-powered electronics.
CVSangtae Kim Hanyang University Electrochemically driven Thermal Energy Harvesting AbstractElectrochemically driven Thermal Energy Harvesting
Thermogalvanic cells offer scalable low-grade waste heat recovery using tunable electrode-dependent thermopower and electrolyte-dependent thermal conductivities. However, the use of single-phase electrodes thermodynamically curb the entropy difference, limiting the thermopower enhancement. Here, we show that phase transforming electrodes achieve significantly enhanced thermopower using the melting phase transition of bulk NaxK alloys. Under both temporal and spatial temperature gradients, the electrodes exhibit significantly increased thermopower up to 26.1 mV/K across the melting point and the generated voltages of 261 mV under 10 K temperature gradient. We also show that stabilizing the liquid metal electrode-electrolyte interface plays a critical role in evaluating the thermopower associated with the phase transition. The strategies demonstrated in this work suggest potential design guidelines towards optimizing thermogalvanic cells to specific temperature ranges.
CVSunghoon Hur Korea Institute of Science and Technology Enhanced Performance of a Thermoelectric Generator by Cantilever Vibration and Piezoelectricity AbstractEnhanced Performance of a Thermoelectric Generator by Cantilever Vibration and Piezoelectricity
Hybrid energy harvesters, combinations of energy harvesters with different harvesting mechanisms, have been proposed to overcome limitations of single method energy harvester. Although the total power is reported to be larger than that of individual power output, most of works reported that the total power output is lower than the summation of individual energy harvesters. Moreover, to the best of our knowledge, no research has been reported that each harvesting method assists the other harvesting efficiency. Here, we present an effective hybrid energy harvester that combines piezoelectricity and thermoelectricity, resulting in a larger final power generation. The piezoelectric cantilever beam was adopted to leverage oscillation-induced cooling effect for the heat dissipation effect, a crucial factor for the thermoelectric power generation. The study also investigates heat dissipation effects with respect to cantilever designs, showing that the trapezoidal cantilever design exhibits the highest displacement and heat dissipation. Furthermore, finite-element analysis is conducted to validate the experimental findings, which are consistent with the measured heat dissipation trends. As a result, the hybrid energy harvesting method achieves a power output of 7.619 mW in the presence of 0.5g vibrational source, more than 50 % increase compared to a static condition. This improved performance demonstrates that one harvesting method can be supportive to the other so that the devised hybrid energy harvester is promising for diverse applications where thermal and vibrational energy sources exist.
CVJeong Min Baik Sungkyunkwan Univ. Functional Electroactive materials for Heat managements and Nanoplastic filtration AbstractFunctional Electroactive materials for Heat managements and Nanoplastic filtration
Tribomaterials are important not only for improving the output performance of energy harvesting devices but also for extending their applications. In general, the static surface charges are created by the contact electrification, in which the driving force is possibly related to the difference of the surface chemical potential. However, as limited by the surface potential difference, the charge density generally cannot reach an ultimate high level to approach, commonly ~ tens of uC/m2.
Here, we present facile strategies to maximize the charge density via sophisticated materials design as well as the potential applications such as Heat managements and nanoplastic filteration. A new dielectric, a C60-containing block polyimide (PI-b-C60)1, a new cationic material structure consisting of SiO2 and MoS2 coated on a Ni-mesh in sequence was presented.2 These materials are applied to enhancing the output voltage of a thermoelectric generator by introducing highly charged polyimide-based dielectrics.3 Finally, an efficient strategy to enhance the filtration of nanoplastic will be also presented.
1. Jae Won Lee, et al, Energy Environ. Sci., 2021, 14, 1004-1015
2. Jin-Kyeom Kim et al, Energy Environ. Sci., 2023, 16, 598-609
3. Sun-Woo Kim, et al, Adv. Energy Mater. 2022, 220298.Il-Kyu Park Seoul National University of Science and Technology Synergistic performance enhancement of nanogenerators based on hybrid nanostructures AbstractSynergistic performance enhancement of nanogenerators based on hybrid nanostructures
With the development of Internet of Things (IoT) technology, energy-harvesting technologies that generate electrical energies from the environment regardless of time and place have attracted much attention. Energy-harvesting technologies enable the operation of mobile devices or wireless sensor networks for the realization of IoT by collecting the wasted energy in various forms, such as mechanical, optical, and thermal energies, and converting them into the form of electrical energy capable of operating widely spread, small electronic devices. Recently, energy scavenging technologies based on energy conversion from various wasted ambient energies to electrical energy have received much attention for self-powering and renewable energy applications. Harvesting abundantly available wasted ambient mechanical (e.g., from human activity, machinery vibration, noise or sound waves, airflow, and water flow), optical (solar, photonic, and radioactive), and electrochemical energies has been a long-standing dream and is being widely investigated for use in sustainable and self-powering systems. In this presentation, the fabrication and applications of various organic-inorganic multi-dimensional nanomaterials will be introduced based on recent developments. In addition, a demonstration of fiber-based nanomaterials for energy conversion devices will be presented. The synergistic enhancement of nanogenerator performances has been verified, and its mechanism was suggested based on hybrid nanostructures. More details about the performances of the devices will be discussed in the presentation.
CVSeungjun Chung Korea University Compliant thermoelectric generators for sustainable self-powered wearables AbstractCompliant thermoelectric generators for sustainable self-powered wearables
Softening of thermoelectric generators (TEGs) allows conformal contact with arbitrary-shaped heat sources, which offers an opportunity to realize self-powered flexible applications. However, existing rigid/flexible thermoelectric devices inevitably exhibit reduced thermoelectric conversion efficiency due to the parasitic heat loss in high-thermal-impedance polymer substrates and poor thermal contact arising from rigid interconnects. In this talk, I would like to introduce our recent efforts to improve the thermoelectric performance of compliant TEGs, which facilitate achieving high energy conversion efficiency in TEGs capable of conforming to 3D surfaces of heat sources simultaneously. In addition, skin-like thermoelectric devices with magnetically self-assembled thermoelectric particles will be presented for realizing fully soft energy harvesting devices.
CVBaojin Chu University of Science and Technology of China Polarized Surface Effect in Ferroelectric Materials AbstractPolarized Surface Effect in Ferroelectric Materials
Flexoelectricity is an electromechanical coupling effect between polarization and strain gradient in dielectrics. This effect has intensively studied in ferroelectrics, but the generating mechanisms are not completely understood. The flexoelectric effect of ferroelectric ceramics was investigated to understand the mechanism of this effect. We found that there exist polarized surface layers on ferroelectric ceramics. The piezoelectric response from the surface layers is a main mechanism responsible for the large flexoelectric-like response of the ferroelectric ceramics, which is much larger than the theoretically calculated response. We show that this polarized surface layer effect also exists in other materials, such as ferroelectric polymers. Our study provides an important mechanism to understand the flexoelectric effect in ferroelectric materials.
CV
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XII. Materials for Enviromantal Science
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Keynote Speakers
Jung Rae Kim
Pusan National UniversityMicrobial CO2 Conversion to Value-added Chemicals using Carbon-negative and Sustainable Microbial Electrosynthesis Cell
AbstractMicrobial CO2 Conversion to Value-added Chemicals using Carbon-negative and Sustainable Microbial Electrosynthesis Cell
Microbial electrosynthesis (MES) is a promising strategy for the conversion of CO2 to useful chemicals. Nevertheless, the characteristics of electrode-associated cells in MES and their metabolic pathway regulation in CO2 fixation have not been elucidated. This work presents the electrode-driven hydrogen and polyhydroxybutyrate (PHB) production from CO2 in Rhodobacter sphaeroides. Under an applied potential of - 0.9 V vs. Ag/AgCl to the cathode and glutamate as nitrogen source, Rhodobacter sphaeroides produced hydrogen (328 mL/L/day) with CO2 as the sole carbon source under illumination. The initial planktonic cells decreased rapidly in suspension, whereas biomass formation on the cathode surface increased gradually during MES operation. With ammonium chloride as nitrogen source, the electrode-associated cells produced PHB at concentrations up to 23.50 ± 2.8% of the dry cell weight (DCW), whereas the suspended cells grew faster but with a lower cellular PHB content. The electron uptake and regulation of the metabolic pathways differed in electrode-associated and suspended R. sphaeroides. Gene expression analyses showed that phaA expression was upregulated in electrode-associated R. sphaeroides, whereas phaB expression was downregulated in suspended cells. The electrode-associated cells expressed unconventional CO2 fixation enzymes, such as isocitrate dehydrogenase and formate dehydrogenase, with more PHB synthesis. These results show that CO2 can be upcycled to polymeric substances and provide novel insights into the genetic regulation of electrode-associated cells in MES.
CVInvited Speakers
Name Affiliation Title Abstract CV Jaesang Lee Korea University Heterogeneous catalysis for oxyanion and ozone activation AbstractHeterogeneous catalysis for oxyanion and ozone activation
Low-valent metal- and carbon-based materials catalyze the redox reactions involving oxyanions (e.g., persulfate and hydrogen peroxide) and ozone to enable the radical and non-radical oxidative degradation of organic compounds in water. Treatment efficiency and major degradative pathway are sensitive to the type of activator and radical precursor. Specifically, the high-yield production of radical oxidants, such as sulfate and hydroxyl radicals, was achievable with reduced transition metals that initiated the heterolytic dissociation of peroxide bonds through the one-electron reduction of oxyanions. Nickel sulfides served as the key species in the catalytic conversion of ozone into hydroxyl radicals whereas contributing to a marked increase in the capability of nickel-carbon composites for non-radical persulfate activation. Low-valent nickel oxide/hydroxide oxidatively transformed into the high-valent counterparts as non-radical oxidants upon the addition of diverse oxyanions, including persulfate and hypochlorite, which contrasted with the observation that reduced cobalt-derived catalysts performed the radical-induced oxidation of organics through the selective activation of peroxymonosulfate. Nanostructured carbons and carbon-encapsulated metals mediated the transfer of electrons from organic compounds as electron donors to persulfate molecules as electron acceptors, which led to the carbocatalytic treatment processes with substrate-specific efficiency and minimal sensitivity to the presence of background organic and inorganic constituents.
Gun-hee Moon KIST Advancing the Oxidation of Aromatic and Plastic Contaminants with Direct Hole-Mediated Pathways in Photocatalytic and Photoelectrochemical Systems AbstractAdvancing the Oxidation of Aromatic and Plastic Contaminants with Direct Hole-Mediated Pathways in Photocatalytic and Photoelectrochemical Systems
The increasing severity of environmental pollution, driven by the persistence of organic pollutants and the accumulation of plastic waste, underscores the critical demand for the formulation of effective and sustainable remediation methodologies. This presentation explores the progress in photocatalytic and photoelectrochemical technologies aimed at the oxidation of aromatic compounds and polymeric substances, highlighting essential studies that reveal the mechanisms and effectiveness of these innovative approaches. It will delve into the methodologies for the selective participation of photo-generated holes in the oxidation of target pollutants. The precise manipulation of reactive species plays a pivotal role in the efficient breakdown of organic contaminants, and a deeper insight into the characteristics of these pollutants, as well as their reactions with specific radical species, is vital for the creation of highly active materials tailored for environmental engineering applications. This cohesive strategy not only addresses the pressing issues of water pollution and waste management but also lays the groundwork for the advent of sustainable technologies capable of converting pollutants into valuable resources. The outcomes emphasize the significance of employing hole-mediated oxidation processes within a comprehensive framework to confront a variety of environmental challenges, thus establishing a novel standard for the efficiency and utility of photocatalytic and photoelectrochemical systems in the field of environmental remediation and resource recovery.
CVSon Moon KIST Battery Materials for Water Treatment and Desalination AbstractBattery Materials for Water Treatment and Desalination
Electrochemical water treatment/desalination processes have been actively investigated for centuries as an alternative to membrane processes due to their low energy consumption. However, it was recently revealed that the process represented by capacitive deionization (CDI) uses less energy, but its energy efficiency is not high (thermodynamic efficiency <1%). In other words, a small amount of energy is used to adsorb a small amount of ions.
To overcome this low energy efficiency, water treatment/desalination processes using Faradaic electrodes, typically battery electrodes, are being developed. This process is very energy efficient because it utilizes ion-selective electrodes (thermodynamic efficiency >10%), and can be widely used from the recovery of ions such as ammonium to brackish water desalination. Another battery technology is a desalination battery, including seawater batteries, which refers to a device that can store ions in the form of energy in electrodes while desalinating water (i.e., sodium ions present in seawater).
Therefore, in this presentation, recent research cases will be introduced on how battery materials can be used for water treatment/desalination. In addition, it will be discussed whether this technology can overcome the limitations of existing electrochemical water treatment/desalination systems.CVSang-Yeop Chung Yonsei University Eco-friendly construction materials incorporating marine wastes and bacteria AbstractEco-friendly construction materials incorporating marine wastes and bacteria
This study explores eco-friendly construction materials by incorporating marine wastes and bacteria into cement-based composites, addressing both environmental concerns and enhancing material properties. The accumulation of waste shells and fishing nets presents significant environmental challenges, including soil pollution and odor issues. Moreover, the construction field faces scrutiny for its substantial energy consumption and CO2 emissions during aggregate production. Our research investigates the potential of recycling various marine wastes, such as cockle, oyster, and murex shells, along with waste fishing nets, by integrating them as partial substitutes for fine aggregates and fibers in cementitious materials. These materials were cleaned using an ultrasonic device or washed, then crushed or ground before incorporation into cement mortar specimens to examine their effects on the material's microstructural characteristics and flexural performance. The results demonstrate that cockle shell powder, when properly processed, serves as a viable alternative to traditional aggregates, and ground waste fishing nets can effectively reinforce cement mortar, improving its flexural properties. Additionally, the utilization of bacterial concrete as a self-healing material, capable of autonomously repairing damages through microbially induced calcium carbonate precipitation (MICP) can be considered a sustainable and environmental approach. The precipitated calcium carbonate, in phases such as calcite and vaterite, significantly enhances the durability and mechanical properties of cement mortar, depending on the curing solutions used. This research not only offers a solution to managing marine waste but also introduces innovative methods to produce more sustainable and durable construction materials, contributing to the reduction of environmental impact in the construction industry.
CVWooyul Kim KENTECH Operando Spectroscopic Analysis for Photo/Electrocatalytic Processes AbstractOperando Spectroscopic Analysis for Photo/Electrocatalytic Processes
Observing key intermediates directly on the catalyst surface poses a significant challenge in various photo/electrocatalytic processes, including CO2 reduction and O2 reduction reactions. To gain a comprehensive understanding of the reaction mechanisms, it is essential to conduct combined studies utilizing complementary tools such as electrochemical characterization, computational calculations, and operando spectroscopies. Among these, time-resolved attenuated total reflection-surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) stands out as particularly suited for investigating electrochemical CO2RR due to its ability to observe interfacial processes in real-time with high surface sensitivity. Time-resolved analysis offered by ATR-SEIRAS allows for the exploration of the kinetic relevance of intermediates and their dynamics in relation to reactants and products during the reaction. Furthermore, integrating operando spectroscopic studies with material characterization enables the correlation of intermediate behavior with catalyst conditions. In this context, I will introduce in situ time-resolved FT-IR (or ATR mode) spectroscopic techniques to capture isotopically labeled products and key intermediates generated during the photoreduction of carbon dioxide.
Sungjun Bae Konkuk University Synthesis of novel remedial materials from solid wastes and their uses for removal of contaminant in wastewater AbstractSynthesis of novel remedial materials from solid wastes and their uses for removal of contaminant in wastewater
Massive amounts of various solid wastes have been produced worldwide from different industrial plants (e.g., coal fly ash from coal fired power plant, red mud from alumina production by Bayer process, and steel slag from steel plant). The solid wastes are usually composed of various metal oxides which can be reutilized as sources of novel material synthesis. Herein, many elements (i.e., Si, Al, Ca, and Fe) were selectively extracted from various solid wastes or used them as support material to effectively remove organic, inorganic, and radioactive pollutants in aqueous environments. All the remedial materials developed from this study showed a great performance in each treatment process which shows the potential conversion of solid wastes into much value-added materials.
CVSeoni Kim Ewha Womans University Chloride-mediated ion separation for CO2 removal from seawater AbstractChloride-mediated ion separation for CO2 removal from seawater
The concentration of CO2 in the atmosphere is on the rise, prompting widespread efforts to extract CO2 from various sources including power plant exhausts, chemical processes, and directly from the atmosphere. Historically, efforts have primarily focused on capturing CO2 from localized sources such as power plants. However, there is increasing interest in negative emission technologies, which aim to remove CO2 that has already been released into the environment. These strategies largely focus on direct air capture, but the relatively low atmospheric CO2 concentration (about 420 ppm) presents challenges due to the slow absorption rates and the energy demands of regenerating capture agents.
The ocean, which has absorbed approximately 30% of anthropogenic CO2 emissions, presents a significant opportunity for CO2 separation due to its higher CO2 concentrations—about 120 times that of the atmosphere. By extracting CO2 from ocean water, we can indirectly lower atmospheric CO2 levels, as the CO2-depleted water can then reabsorb CO2 from the air, potentially reducing overall atmospheric concentrations. A critical aspect of this technology is the environmentally responsible reintroduction of treated water back into the ocean, which involves minimizing chemical additives and avoiding the production of harmful byproducts. The electrochemical method offers distinct advantages here, eliminating the need for external chemicals and providing fine control over the reaction through voltage adjustments.
In this presentation, a new electrochemical system composed of two different chloride-capturing electrodes will be introduced to modulate the alkalinity of seawater and extract CO2 as a gas phase. This system could successfully remove carbon dioxide from seawater without introducing an ion exchange membrane.CVWooChul Song Postech TBD Sanghyun Jeong Pusan National University Dual Resistance Janus PDA/Patterned PVDF Membrane for Membrane Distillation with Early Wetting Detection using Electrochemical Impedance Spectroscopy AbstractDual Resistance Janus PDA/Patterned PVDF Membrane for Membrane Distillation with Early Wetting Detection using Electrochemical Impedance Spectroscopy
Membrane distillation (MD) stands out as a promising separation technology due to its high efficiency and minimal energy requirements. However, issues like membrane fouling and wetting persist, particularly when dealing with low surface tension substances such as oil and surfactants. To tackle these challenges, researchers have developed novel MD membranes with asymmetric wettability, known as Janus membranes, featuring a hydrophilic layer atop a hydrophobic layer. This configuration allows the hydrophilic side to remove hydrophobic contaminants while the hydrophobic side exhibits remarkable resistance to wetting. In this study, a Janus polydopamine (PDA)/patterned polyvinylidene fluoride (PVDF) membrane was fabricated using non-solvent- and vapor-induced phase separation methods. This membrane, with its hydrophobic patterned PVDF layer, effectively delayed membrane wetting without significantly compromising flux (12.50 to 11.42 LMH) or permeate conductivity (up to 2.37 µS m-1). Additionally, the hydrophilic PDA layer prevented oil from interacting with the membrane surface, enabling stable operation for over 10 h. The membrane's performance was evaluated in direct contact MD (DCMD) setups using both a 3.5 wt.% NaCl feed solution with hourly sodium dodecyl sulphate injection and a 3.5 wt.% NaCl feed solution containing 1000 mg L-1 oil. Notably, the wetting of the membrane was systematically monitored in real-time using electrochemical impedance spectroscopy (EIS). The Janus membrane exhibited decreasing normalized impedances corresponding to different wetting stages, ranging from 0.99 to 0.45 during partial wetting and eventually reaching 0.00 during full wetting. Simultaneously, wetting fronts gradually increased from 0% to 82% and ultimately to 100% with membrane wetting. Compared to conventional electrical conductivity measurement methods, EIS with impedance and wetting front analysis provided more precise detection during DCMD operation. This study showcases the effectiveness of Janus membranes in mitigating membrane wetting and highlights the real-time monitoring techniques like EIS for understanding membrane performance under dynamic conditions.
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XIII. Advanced Materials and Technologies for Next-Generation Solar Cells
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Keynote Speakers
Kwanyong Seo
UNISTHarnessing Light Energy with Crystalline Silicon Nano- and Micro-Structures
AbstractHarnessing Light Energy with Crystalline Silicon Nano- and Micro-Structures
Recent advances in nanotechnology and our growing understanding of how light interacts with nano- and micro-structures have significantly improved our ability to capture and manipulate light. In this talk, I will discuss research results that have leveraged crystalline silicon micro-structures as a promising approach for developing next-generation energy-harvesting devices from solar energy. Specifically, micro-structuring crystalline silicon enables the creation of novel devices, such as flexible and transparent solar cells—applications not previously feasible with traditional, rigid, and opaque crystalline silicon. Moreover, crystalline silicon is considered a leading material for solar-to-chemical conversion applications. I will also present demonstrations of an artificial leaf for water splitting and a large-scale hydrogen generation system using crystalline silicon. Additionally, I will introduce a discussion on a nanowire-based photodetector with high external quantum efficiency.
CV
Jun Kun Lee
University of PittsburghControlling the Crystallization of Halide Perovskite Film for Solar Cell Applications
AbstractControlling the Crystallization of Halide Perovskite Film for Solar Cell Applications
Due to the outstanding properties and solution processability, organometal halide perovskite solar cells (PSCs) rapidly emerge as a high-efficiency and low-cost photovoltaic technology. One of key issues in the manufacturing of PSCs is the facile growth of the halide perovskite films, which is covered in this presentation.
The 1st part of the presentation will show how engineer the SnO2/perovskite interface by introducing a thin PbS quantum dots (QDs) interlayer and explored the dual roles of PbS QDs in the passivation of SnO2 ETL and the crystallization of the active PVK layer. A solution of PbS QDs was spin-coated on the SnO2 film to passivate dangling Sn bonds on the top of SnO2 and anchor the iodide on the bottom of active layers. The PbS modifier dramatically decreases the defects at the interlayer and suppresses the nonradiative recombination of the deivces. In addition, the PbS QDs underlayer assists the nucleation of perovskite film by stabilizing the intermediate phase between δ and α-FAPbI3 phases. The PVK layer grown on the SnO2-PbS ETL has a better morphology and crystallization.
The 2nd part of the presentation will address the combination of solvent engineering with the inkjet printing, which can be used for large-scale PSCs fabrication. This presentation reports the printing process of the perovskite precursor solution using a single nozzle printer and the crystallization process of the inkjet-printed perovskite films by solvent engineering. Concerning antisolvent bathing, we systematically studied the effect of the polarity difference between the solvent and the antisolvent on the crystallization and grain growth of the film. It is found that the difference in polarity of solvents and antisolvents proved to be a valuable indicator of if an intermediate phase would form, which in our case was essential for dense grain growth.CVInvited Speakers
Name Affiliation Title Abstract CV Wanchun Xiang Shaanxi Normal University Efficient and stable inorganic perovskite solar cells AbstractEfficient and stable inorganic perovskite solar cells
Inorganic perovskites hold promise for improving stability of perovskite solar cells (PSCs). [1] However, the narrow-bandgap inorganic perovskite is thermodynamically unstable at room temperature, limiting the development of stable PSCs. In addition, severe nonradiative charge recombination at interface restrains the obtainment of high efficiency devices. Among different types of defects responsible for energy loss, iodide vacancies exhibit the lowest formation energy and therefore dominate at perovskite surface. We show that compositional engineering by doping significantly stabilizes the α-phase of inorganic perovskite at room temperature. [2-3] By further developing interfacial modifiers with functions such as synergetic passivation [4], chelation [5], the defect density of inorganic perovskite films can be appreciably reduced. The coordination of lithium ions and the introduction of cross-linked hydrophobic layer further enhance the device stability, while maximizing the power conversion efficiency of inorganic PSCs to 21.8% (n-i-p structure) and 21.0% (p-i-n structure), both are the highest efficiencies so far for the corresponding device structures [6-7].
References
[1] Energy Environ. Sci, 2021, 14, 2090-2113.
[2] Joule, 2019, 3, 205-214.
[3] Nat. Commun, 2019, 10, 4686.
[4] Angew. Chem. Int. Ed, 2021, 60, 23164-23170
[5] Angew. Chem. Int. Ed, 2023, 135, e202216634
[6] Adv. Mater, 2023, 36, 2306982
[7] Adv. Mater, 2024, 202312237CVEdgardo Saucedo Silva Polytechnic University of Catalonia (UPC) – Barcelona Tech All about solution based kesterite solar cells for new record efficiency over 15% AbstractAll about solution based kesterite solar cells for new record efficiency over 15%
The synthesis of multinary semiconductors for solar energy conversion applications such as kesterite (Cu2ZnSn(S,Se)4, CZTSSe) is extremely challenging due to the complexity of this type of compounds. Having multiple elements in their structure, the formation of secondary phases, punctual or extended detrimental defects, and/or singular interfaces is commonly very problematic. In particular, quaternary kesterite-type compounds are not the exception, and all these detrimental issues explain why during almost 10 years the world record efficiency was unchanged. But the very recent development of molecular inks route with special precursors, allows the accurate control of single kesterite phase with high crystalline quality. In addition, the use of selective diluted alloying has shown a high potential for minimizing detrimental punctual defects formation, contributing to increase the conversion efficiency record of kesterite based solar cells up to 15% in a short time.
This presentation will be focused first in demonstrating how the molecular inks synthesis route was of key relevance for the control of high-quality single phase kesterite, through the modification of the synthesis mechanisms. The relevance of the composition of the ink, the precursor salts, and the interaction between the solvent and the cations in the solution is key for a reliable and reproducible high efficiency kesterite production baseline. Then, diluted alloying/doping strategies will be presented including Cu, Zn and Sn partial substitution with elements such as Ag, Li, Cd or Ge. The positive impact of these cation substitutions will be discussed in regards of their impact on the kesterite quality, as well as on the annihilation of detrimental punctual defects, allowing for new efficiency records at 15% level.
Finally, very recent, and innovative interface passivation strategies will be discussed, showing the pathway to increase the record efficiency beyond 20%.CVChun Cheng Southern University of Science and Technology Dual molecular bridges at perovskite heterointerfaces for efficient inverted solar cells with fill factor beyond 0.87 AbstractDual molecular bridges at perovskite heterointerfaces for efficient inverted solar cells with fill factor beyond 0.87
Utilizing molecular bridges presents a promising means to enhance the performance of perovskite solar cells (PSCs) by boosting fill factor (FF). However, concurrently bridging the perovskite absorber and its adjacent interfaces is challenging. Here, we construct dual molecular bridges at perovskite heterointerfaces, enabled by a self-organizing additive of 4-fluoro-phenethylammonium formate (4-F-PEAFa) and a customized hole transporter of [2-(7H-dibenzo[c,g]carbazol-7-yl)ethyl]phosphonic acid (DBZ-2PACz). The molecular bridges spanning two interfaces lead to the formation of an “integral carrier transport pathway”, mitigating both non-radiative recombination and charge-transport losses in the fabricated PSC devices. We thus achieve a remarkable power conversion efficiency (PCE) of 26.0% (25.6% certified) in inverted PSCs, accompanied by a high fill factor of 0.87 and a low ideality factor of 1.06. The unencapsulated devices retain 96% of their PCEs after aging at 85 °C for 2200 hours and 90% after maximum power point tracking at an elevated temperature of 50 °C for 973 hours.
CVJangwon Seo KAIST Efficient and Stable Perovskite Solar Cells through Rationally Designed Hole Transporting System AbstractEfficient and Stable Perovskite Solar Cells through Rationally Designed Hole Transporting System
Since 2009, the power conversion efficiencies (PCE) of perovskite solar cells (PSCs) have increased from 3.8% to 26.1% over the last decade. Most highly efficient PSCs employ an n-type layer of mesoporous titanium dioxide or tin oxide in an n-i-p device configuration, where organic/polymer conductors are commonly used to transport holes into a metal. Numerous efforts have thus far been devoted to achieving a defect-free perovskite film with high-quality morphologies for achieving reduced loss-in-potential results and increased efficiency levels. These comprehensive advances in interface engineering, composition engineering, and charge-transporting layer engineering for perovskite solar cells allow us to attain a PCE greater than 25%. In this talk, I will present our contribution to enhancing photovoltaic performance for PSCs. Furthermore, much efforts have been made to ensure both high efficiency and long-term stability, in research to commercialize PSCs. The doped hole transporting layers (HTLs) with lithium-based hygroscopic dopant are not stable under high thermal stress, which is a primary cause of device degradation. Thus, I will discuss rationally designed HTL system for efficient and stable PSCs and also present our recent work to introduce new dual-functional ionic liquid (IL) dopants into HTL. Finally, I will briefly introduce our efforts to develop scalable PSCs for practical applications.
CVJun Hong Noh KAIST Interfacial Design in Halide Perovskite Solar Cells AbstractInterfacial Design in Halide Perovskite Solar Cells
Halide perovskite solar cells (PSCs) exhibit a thin-film device architecture wherein the light-absorbing perovskite layer is sandwiched between n-type and p-type semiconducting layers. The electric field within the light-absorbing layer can be finely tuned not only through the implementation of charge-transporting layers (CTLs) but also via meticulous interfacial design between the perovskite and CTLs. Additionally, the optimization of radiation from stacked perovskite layers within the entire device, achieved by minimizing non-radiative recombination processes, holds the potential to enhance performance through mechanisms such as photon recycling and scattering. Consequently, the strategic interfacial design on both sides of the perovskite layer, addressing both electrical field distribution and optical radiation characteristics within the thin-film solar cell architecture, emerges as a crucial factor in approaching the radiative efficiency limit. This presentation will delve into our recent efforts in interfacial design, aimed at bolstering the photovoltaic performance of PSCs through refined electrical and optical strategies.
Inchan Hwang KIER Large-area CIGS Solar Cells with Non-toxic Buffer Layer and Microgrid Electrode AbstractLarge-area CIGS Solar Cells with Non-toxic Buffer Layer and Microgrid Electrode
The efficiency of copper indium gallium selenide (CIGS) solar cells using transparent conductive oxide (TCO) decreases significantly with increasing the device area due to TCO's poor electrical properties. Developing high-efficiency large-area CIGS solar cells requires a novel top electrode that has high transmittance and conductivity. In this study, a microgrid/TCO electrode is developed to minimize optical and resistive losses for developing highly efficient large-area CIGS solar cells. Also, the buffer layer of the CIGS solar cells is changed from the CdS buffer to a ZnMgO (ZMO) buffer to increase device efficiency by reducing parasitic absorption in the short-wavelength region. By applying the ZMO buffer and the microgrid electrode, the CIGS solar cell with an increased device area of up to 20 mm × 70 mm exhibits an efficiency of up to 19.7%.
CVJeung-hyun Jeong KIST Bifacial Cu(In,Ga)Se2 solar cells for enhanced efficiency, modularization, and durability AbstractBifacial Cu(In,Ga)Se2 solar cells for enhanced efficiency, modularization, and durability
The Cu(InGa)Se2 (CIGS) solar cell exhibits strong potential in future energy markets such as building, mobility and public facilities due to its high efficiency, good stability, and outstanding applicability. By replacing the opaque Mo back electrode with a transparent conducting oxide (TCO) film in a bifacial cell structure, it is possible to increase the photovoltaic power output from rear light incidence, improve processability of laser scribing for modulation, and enhance mechanical stability in a flexible application due to high interface adhesion at TCO/CIGS. However, the interface presents challenges in forming ohmic contacts and has a high recombination rate at the interface, which degrades the photovoltaic efficiency. In this study, we applied ITO thin films as the back electrode and explored ohmic contact formation and interface passivation capabilities. We presented several ways to form an ohmic ITO/CIGS interface and compared their passivation abilities, achieving over 20% cell efficiency for front light incidence and at the same time the rear incident photocurrent comparable to 20 mA/cm2. During the P3 laser scribing required for fabricating monolithic-integrated module, laser heating can damage the CIGS/CdS interface, inevitably reducing photovoltaic efficiency. By directing the laser from substrate, heating of the CIGS/CdS interface by the laser can be avoided, thus securing excellent P3 scribing performance. The electrical degradation mechanisms associated with different P3 scribing processes were compared. Additionally, CIGS solar cells can be implemented as flexible modules on polyimide films. Replacing the conventional Mo back electrode with ITO significantly improved mechanical stability. Especially in repeated bending tests, while the efficiency stability of cells were no different between Mo and ITO back electrode, the modules demonstrated vastly superior stability with ITO. We successfully demonstrated transparent solar module and flexible module by employing the bifacial CIGS cell structure and the laser processing techniques, achieving either excellent transparency or flexibility, together with enhanced modulation and durability due to improved interface adhesion of TCO/CIGS.
CVJin Young Kim UNIST High-Performance Perovskite/Organic Tandem Solar Cells with Mixed Self-Assembled Monolayers AbstractHigh-Performance Perovskite/Organic Tandem Solar Cells with Mixed Self-Assembled Monolayers
Perovskite/organic tandem solar cells offer a promising avenue to surpass the Shockley-Queisser limit by mitigating thermalization losses. However, wide bandgap perovskite solar cells (WBG PSCs) face challenges, particularly in open-circuit voltage losses. Herein, we propose a novel approach employing a mixed self-assembled monolayer (mSAM) as a hole-selective layer (HSL). This strategy facilitates efficient hole extraction by homogenizing the surface potential of the HSL. Furthermore, the modification of indium tin oxide with mSAM enhances perovskite crystallinity, reducing lattice strain and phase segregation. We have significantly improved the device efficiency, achieving a power conversion efficiency of 18.85% for WBG PSCs and 24.73% for perovskite/organic tandem cells. These results demonstrate the potential of the mSAM strategy to advance both the performance and stability of perovskite-based tandem solar cells for practical renewable energy applications.
CVYun-Hi Kim Gyeongsang National University Development of Organic Semiconducting Materials for OPV AbstractDevelopment of Organic Semiconducting Materials for OPV
Organic solar cells have attracted great attention as next-generation wearable power generators due to their merits of light-weight, low cost, and potential stretchability. One of the most successful advances in improving the power conversion efficiency (PCE) of OSCs has been recently achieved with the advent of non-fullerene small molecule acceptors (NFSMAs). A highly fused backbone structure of the NFSMAs incorporated with strong dye molecules allow to a high absorption coefficient compared to conventional fullerene-based acceptors, leading to the drastic improvement of the light absorption and the PCE of OSCs to 19%. In this presentation, I will discuss the design strategies of Non-fullene acceptors for good stability as well as high efficiency. Despite recent successes of the NFSMA-based OSCs, morphological instability and sharp domain interfaces caused by strong crystalline and high diffusion properties of the NFSMA can limit long-term stability and mechanical reliability for their practical applications. In this regard, all-polymer solar cells (all-PSCs)—consisting of a polymer donor (PD) and a polymer acceptor (PA)—are a particularly attractive class of the PSCs due to their excellent morphological stability and mechanical robotness . Here, we report a new series of NFSMA-based PA materials containing the same building blocks of PD to enhance the molecular compatibility between PA/PD, achieving high mechanical robustness and efficiency of all-PSCs.
Sung-Yeon Jang UNIST High-Performance Solar Cells Based on Low Bandgap Organic Perovskite Quantum Dots AbstractHigh-Performance Solar Cells Based on Low Bandgap Organic Perovskite Quantum Dots
In the last ten years, the field of solution-processed solar cells has advanced significantly. This improvement is mostly due to the search for new materials and the perfection of manufacturing techniques aimed at increasing the efficiency and market viability of solar cells. Currently, the focus of research has shifted towards not only enhancing efficiency but also expanding the variety of solar cell technologies and improving production methods. In this scenario, quantum dot technology stands out as a promising avenue for innovation. The unique properties of quantum dots present exceptional opportunities for groundbreaking work. This presentation will cover the progression of quantum dot solar cells, from foundational concepts to the latest technological achievements. We'll examine how quantum dots operate, highlighting their role in mitigating defects and stabilizing phases. Utilizing the quantum effects of these dots is a key tactic for improving stability and addressing challenges in defect management. This method paves the way for new directions in solar cell research and promises a future filled with innovative developments.
Ka-Hyun Kim Chungbuk National University Deep level transient spectroscopy and capacitance transient of silicon heterojunction solar cells AbstractDeep level transient spectroscopy and capacitance transient of silicon heterojunction solar cells
Deep Level Transient Spectroscopy (DLTS) and Capacitance Transient (CT) are widely used experimental techniques for characterizing the electronic properties of semiconductor materials and devices, including solar cells. This work presents a comprehensive study on the application of DLTS and CT in investigating deep-level defects in solar cells. The DLTS technique enables the identification and quantification of deep-level defects within the semiconductor bandgap, significantly impacting the performance and efficiency of solar cells. By measuring the device's transient response under certain bias conditions, DLTS provides valuable information about the energy levels, capture cross sections, and densities of these defects. This information is crucial for understanding charge carrier recombination processes and optimizing solar cell fabrication processes. The CT behavior of pn junctions can be analyzed using exponential fitting, providing direct information about the trap density, emission rate, and capture cross section of the defects. However, in modern semiconductor devices, including high-efficiency solar cells, the complicated device structure results in multiple exponential decays in its CT behavior that overlap. Therefore, an appropriate method to interpret CT results is required. In this study, DLTS and CT measurements were performed on silicon heterojunction solar cells. The obtained results shed light on the nature of defect states, leading to a better understanding of the device physics and potential avenues for performance enhancement. The findings presented in this work demonstrate the significance of DLTS and CT techniques in characterizing solar cells, providing valuable information for device optimization and the development of more efficient photovoltaic technologies.
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XIV. Water splitting, CO2 reduction
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Keynote Speakers
Bharat Kale
MITWPUHighly stable and crystalline semiconductor quantum dot glassy materials for energy genration and storage.
AbstractHighly stable and crystalline semiconductor quantum dot glassy materials for energy genration and storage.
Major advances have been made recently in exploring new kinds of Quatum dots (QDs)-embedded glasses for variety of optial applications. These QD-glasses demonstrtaed efficient and stable luminiscence in the visible to mid IR range and showed many competitive applications such as phosphors and optical fibre applifiers. However, this is the first time, we have used such unique glass for energy and energy storage applications. It is well known that semiconductor quantum dots are unstable at ambient conditions and hence it is very difficult to study their size quantization and functionality, precisely. In view of this, the semiconuctor quntaum dots of different size ( 2-7 nm) are grown in the glass matrix and studied the optical properties. These Q dot semiconductor glasses are highly stable and can be used for optical applications.The CdS, CdSSe, bismuth quantum dots grown in glass matrix have shown fantastic optical properties and used for solar light harvesting to produce hydrogen. More significantly, the oxide semiconductor Ag3PO4 quantum dots of size (1-5 nm) have been grown in glass matrix which shows an excellent optical property. The dodecahedrons of Ag3PO4 are also been seen at nano phase state in glass matrix which is quite unique. The uniform distribution of very tiny quantum dots have been observed in glass matrix which are quite stable up to 300 °C. The fabrication of variety of quantum dot glasses have been demonstrated for hydrogen production. The hydrogen generation using such systems has been demonstrated for the first time. More significantly, these quantum dot glasses have also been used for the lithium-ion battery applications for the first time. There will be huge potential for these glasses to explore them further for energy applications.
CVInvited Speakers
Name Affiliation Title Abstract CV Han-Hee Cho UNIST Organic Photoelectrochemical Cells for Overall Solar Water Splitting AbstractOrganic Photoelectrochemical Cells for Overall Solar Water Splitting
Solar-driven water splitting to produce hydrogen and oxygen offers a promising avenue for reducing reliance on fossil fuels as hydrogen can be converted into electrical energy using a fuel cell or transformed into useful chemical feedstocks. Despite its potential, the search for cost-effective light harvesting semiconductors suitable for industrial-scale deployment remains a challenge. Organic photoelectrochemical cells (OPECs) utilizing organic semiconductors (OSs) coupled with co-catalysts have recently attracted great attention as alternative photoelectrodes for solar water splitting, considering unique features of OSs such as precisely tunable optoelectrical properties and solution-processability at low temperature. However, the conversion efficiency and stability of OPECs (both photocathode and photoanode) have remained particularly poor. Herein, we present high-performance and robust organic photoelectrochemical cells by employing a bulk heterojunction (BHJ) blend of semiconducting polymers as a photoactive layer. Our in-depth study on photoreduction and photooxidation by OPECs identifies critical parameters that determine the performance and operational stability: (i) rational selection of semiconducting polymer donor and acceptor to generate free charges efficiently and ensure chemical stability upon illumination, (ii) large surface roughness of interlayers to improve interfacial adhesion, and (iii) mitigation of charge accumulation at the interfaces. By leveraging these findings, our optimized polymer BHJ photocathode and photoanode show outstanding performance and unprecedented robustness compared to previous OPECs, demonstrating a new benchmark of OPECs for solar water splitting. Consequently, this advancement, combined with the simplicity of the polymer blending process, establishes polymer BHJs as a promising route for efficient and scalable solar-driven water splitting technology.
CVAn Hardy Hasselt University (Photo)electrocatalysis towards water splitting and CO2 reduction based on inorganic materials from solution based synthesis Abstract(Photo)electrocatalysis towards water splitting and CO2 reduction based on inorganic materials from solution based synthesis
Solution-based synthesis methods for inorganic materials share a common starting point: the liquid solution phase. These methods encompass various classes like sol-gel, precipitation (hydro- or solvothermal), each offering different variants based on reagents, structure directing agents, and process parameters such as temperature and pressure. This variability allows for control over material composition, structure, and morphology, influencing catalytic properties relevant to applications like water splitting and CO2 conversion.
Hydrothermal precipitation, illustrated by CuFeO2 synthesis, involves Cu(II) and Fe(II) precursors undergoing redox reactions to form Cu(I) and Fe(III), crucial for CO2 reduction. Optimizing conditions is vital to prevent undesired secondary phases. Systematic investigation of Fe/Cu ratios during synthesis aids in this optimization, offering insights into reaction mechanisms. Oxide synthesis involves anion supply either from ambient O2 during calcination or from the solvent (water) during hydrolysis. Conversely, sulfide synthesis relies on precise control of metal ion precipitation through selected sulfide sources to manage nucleation rates and particle size. Hydrothermal conditions, including temperature and pressure, impact crystallinity and morphology of the reaction products obtained. For instance, MoS2 spherical aggregates synthesized under varying conditions exhibit different electrocatalytic properties for water splitting.
For thin films, chemical solution deposition via spin coating is preferred over hydrothermal methods. Aqueous solution-gel synthesis, suitable for complex oxides like CuBi2O4 used in photoelectrochemical water splitting, yielded optimal performance at a film thickness of 135 nm, achieving high photocurrent densities.
In summary, the importance of solution based synthesis routes for water splitting and CO2 reduction via (photo)electrochemical methods will be demonstrated in this overview presentation of our group’s recent work.
The authors acknowledge support by the Flemish Research Foundation (FWO, G053519N), by SYNCAT, a Flemish cSBO Catalisti MOT3 Moonshot, Vlaamse Veerkracht green H2 and UHasselt cleanH2 BOF21GP04 projects.CVYongfa ZHU Tsinghua University Organic Semiconductor Photocatalysts for Water split under Solar Irradiation AbstractOrganic Semiconductor Photocatalysts for Water split under Solar Irradiation
Self-assembled PDINH supramolecular is an effective visible-light photocatalyst for oxygen evolution. Strong π-π stacking between PDINH molecules enables effective long-range electrons delocalization and accordingly promotes photo-generated charge migration and separation, leading to its remarkable photocatalytic activity. The highly crystalline perylene imide supramolecular photocatalyst is prepared. The catalyst possesses a breakthrough photocatalytic oxygen performance (40.6 mmolg-1 h-1 ), which is 1353 times higher. The SA-TCPP can powerfully spilt water to hydrogen and oxygen at 40.8 and 36.1 μmol·g-1·h-1. Photogenerated holes work as the most significant radical in the photocatalytic therapy process, which is abundant on the surface of photocatalyst in cytoplasm. The solid tumors was completely removed via photocatalysts injection and red-light irradiation. The donor-acceptor (D-A) TPPS/C60-NH2 photocatalyst was prepared by ionic self-assembly (ISA) method. The photocatalytic H2 production rate of TPPS/C60-NH2 is greatly improved, which is 17.71 times than the pure TPPS.
A highly crystalline urea-perylene imide polymer photocatalyst has been successfully built, which achieves super efficient oxygen evolution production (3223.9 μmol g-1 h-1) without cocatalysts. Its performance is 106.5 times higher than conventional PDI supramolecular photocatalyst. The g-C3N4/rGO/PDIP Z-scheme heterojunction has been successfully constructed and shows an efficient and stable photocatalytic overall water splitting performance with H2 and O2 production rate of 15.80 and 7.80 μmol h-1, respectively, about 12.1 times higher than g-C3N4 NS. Meanwhile, the notable AQE of 4.94% (420 nm) and solar-to-hydrogen energy conversion efficiency of 0.30% are achieved. The tetracarboxylic perylene and HOF supramolecules with hydrogen production performance of 120 mmolg-1h-1 and 1046 mmolg-1h-1 were obtained. In addition, the organic semiconductor photocatalyst also has excellent hydrogen peroxide production ability, and the sunlight conversion efficiency reaches 1.8%.CVDongWon Chun KIST Direct observation of hydrogen-sorption kinetics in metal-hydrides for solid-state hydrogen storage through in-situ transmission electron microscopy AbstractDirect observation of hydrogen-sorption kinetics in metal-hydrides for solid-state hydrogen storage through in-situ transmission electron microscopy
Hydrogen is being widely explored as a promising alternative to fossil fuels in light of its numerous advantages, for example, its abundance on Earth, high energy density, and low environmental impact upon combustion. In particlular, solid-state hydrogen storage system is attracting significant attention due to its potential for lower working pressures and higher volumetric energy density. Nevertheless, the utilization of metal-hydrides as hydrogen storage systems faces significant challenges owing to thermodynamic and kinetic limitations, hindering their widespread adoption.
Detecting hydrogen atoms, consisting of a single electron and proton, is challenging particularly when they are incorporated into metals to form metal-hydrides. Therefore, the hydrogen-sorption processes in metal-hydrides have not been thorougly studied. The development of in-situ transmission electron microscopy (in-situ TEM) systems allows to observe materials behaviors directly under working conditions including heating, electrica biasing, and exposure to liquid or gaseous environments at the atomic scale with high temporal resolution.
In this presentation, I will discuss direct observation of hydrogen absorption and desorption process in Mg-X composite metal-hydrides (where X represents Fe and Ni) for solid-state hydrogen storage system. By using an in-situ gas holder system, I track the hydrogenation and dehydrogenation processes of Mg-X metal hydrides. Also, I will explain how we can extract the thermodynamic and kinetic parameter from our experimental findings.
Furthermore, I will introduce the hydrogen absorption and desorption processes in single Pd nanoparticles using environmental-TEM where the relationship between hydrogen-sorption kinetics and crystal orientations are explored.CVXiaotai Wang Xi'an Jiaotong-Liverpool University TBD Mahesh Suryawanshi UNSW Sydney Solar Catalysts for Transforming Sunlight into Green Hydrogen and Beyond AbstractSolar Catalysts for Transforming Sunlight into Green Hydrogen and Beyond
The development of sustainable materials using scalable methods that can enable high-efficiency solar energy conversion devices to produce hydrogen fuel is critical for better utilizing the world‘s abundant solar resources and accelerating the much-needed renewable energy transition. Chalcogenide and chalcogenide-halide materials possess environmentally friendly, non-toxic, inexpensive, and earth-abundant constituent elements and exhibit a band gap in the range of (~ 1.0 to ~ 2.0 eV) and a high absorption coefficient (~ 104 cm-1), making them promising in these sustainable energy technologies.
In this talk, I will talk about our recent research advances in the development of chalcogenide and emerging chalcogenide-halide materials and their applications in solar hydrogen production. In addition to this, I will also talk about our recent developments in PV-driven electrolysis using earth-abundant catalysts for producing hydrogen and value-added chemical products. Current bottlenecks and future, promising directions will also be discussed.CVArchana Kalekar Institute of Chemical Technology (ICT), Mumbai, Maharashtra TBD CV