bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation Behavior of Nanoholes in Porous Ga Oxide
Authors: Kondo Toshiaki
Published: December 2024

Fabrication processes of porous Ga oxide have attracted attention due to its useful semiconductor properties of Ga oxide that allow completely decomposing water. The porous Ga oxide is expected to be applied to various energy conversion devices, such as hydrogen generation devices. The performance of the devices highly depends on their geometrical structures in addition to their semiconductor properties. Therefore, to improve the device performance, geometrical control of the porous Ga oxide is important. One of the fabrication processes of the porous Ga oxide is an anodization process. An advantageous point of the anodization process is the good controllability of the geometrical structures of the nanohole array. Until now, our group has reported the fabrication process of porous Ga oxide having an ideally ordered nanohole array structure by the anodization process utilizing a pretextureing process [1]. This pretexturing process had been originally proposed to fabricate an ideally ordered anodic porous alumina [2]. Prior to the anodization, an ideally ordered array of nanometer-sized concaves was formed onto the surface of Ga metal by the pretexturing process. During the anodization of the textured sample, the nanoholes preferentially grew from each concave, then, an ideally ordered nanohole array was obtained. However, the formation of straight nanoholes having a high aspect ratio was difficult although various anodizing conditions were considered. In the present research, the formation of a porous Ga oxide having a high aspect ratio was studied [3]. It was observed that the growth direction of nanoholes depends on the crystal orientation of Ga metal. The growth direction of the nanohole was almost coincident with the certain crystal axis of Ga metal when the anodizing voltage was low. The present fabrication process is expected to be applied to fabricate various energy conversion devices requiring a geometrically controlled porous Ga oxide, such as hydrogen generation devices.

[1] T. Kondo, Y. Kuroda, T. Shichijo, T. Yanagishita, H. Masuda, J. Vac. Sci. Technol. B, 40, 010603 (2022).

[2] H. Masuda, T. Yanagishita, T. Kondo: “Fabrication of Anodic Porous Alumina”, Encyclopedia of Interfacial Chemistry 1st Edition, Elsevier (2018).

[3] T. Kondo, Sci. Rep., 13, 12408 (2023).
(Invited) Slit Pores Engineering in 2D Layered MXenes for Electrochemical Energy Storage and Conversion
Authors: Naguib Michael
Published: December 2024

MXenes constitute a diverse family of 2D transition metal carbides/nitrides, characterized by the formula Mn+1XnT
x
(where M represents an early transition metal, X denotes carbon or nitrogen, n ranges from 1 to 4, and T
x
indicates surface terminations). Their exceptional electrical conductivity and ion-hosting capacity make them outstanding candidates for electrode materials in electrochemical energy storage systems. The interlayer spacing in MXenes can be considered as tunable slit pores. While intercalation plays a pivotal role in the applications of MXenes as a mechanism for ion storage, the impact of pre-intercalation on their electrochemical performance is not well understood. In this context, we will discuss several examples where pre-intercalation and slit pores engineering have significantly altered the electrochemical behavior of MXenes. Manipulating Ti3C2T
x
MXene multilayers through pre-intercalation has yielded an ultra-high areal capacitance of up to 5.7 F/cm2—a record for MXenes. Notably, engineering the slit pores through pre-intercalation, with an interlayer spacing of approximately 2.2 nm, has achieved a capacitance of 257 F/g—an order of magnitude higher than that of pristine MXene—across a voltage window exceeding 3V in pure EMIMTFSI electrolyte. This outcome results in a high-energy density comparable to batteries without compromising their impressive power density. The slit pores in MXenes can also support the growth of other nanomaterials such as nitrogen-doped carbon sheets. The hybrid of Ti3C2T
x
with confined nitrogen doped carbon in the slit pores have demonstrated a reversible sodium-ion specific capacity of 305 mAh/g at a specific current of 20 mA/g, 2.3 times that of pristine multilayer MXene. For Li-ion batteries, a reversible capacity of 400 mAh/g at a specific current of 20 mA/g has been achieved, which is 1.5 times that of Ti3C2T
x
MXene.
Early Detection Strategies for Lithium-Ion Battery Safety in Electric Vehicles
Authors: Torres-Castro Loraine , Bates Alex Martin , Johnson Nathan Brenner , Quintana Genaro
Published: December 2024

Lithium-ion batteries (LIBs) play a crucial role in the electrification of the automotive industry. However, onset of thermal runaway due to failure modes can occur under a variety of conditions including extreme cycling, regular operation, and even rest. Current battery management systems (BMS) often fail to detect thermal runaway until failure is imminent, providing limited intervention opportunities. This study evaluates advanced diagnostic techniques aimed at providing earlier warnings of LIB failures, thereby enhancing safety protocols within EV battery packs.

An assessment of the effectiveness of commercial gas sensors and rapid electrochemical impedance spectroscopy (EIS) will be presented, including their ability to determine warning times as cells are subjected to thermal and electrical stress. Data from these diagnostics are analyzed alongside real-time gas emissions using Fourier Transform Infrared Spectrometry (FTIR) and Mass Spectrometry (MS) to gain insights into the failure mechanisms of abused cells. The correlation of rapid EIS and gas sensor data with FTIR and MS analyses helped identify specific markers indicative of the onset of instability within the battery cells. These markers, which could be detected well in advance of critical failures, could be integrated into a BMS to enhance the safety and reliability of LIBs, mitigating the hazards associated with batteries in EVs. Our findings suggest a path forward for incorporating these diagnostic measures into the standard BMS to continuously monitor the state of stability of cells and battery packs, potentially revolutionizing battery safety in the automotive industry.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. SAND2024-04747A
Identifying Variability across Institutions in Differential Scanning Calorimetry for Materials Level Battery Safety
Authors: Johnson Nathan Brenner , Bhargava Bhuvsmita , Bates Alex Martin , Diaz Megan , Albertus Paul , Torres-Castro Loraine , Preger Yuliya
Published: December 2024

With the growing concern over Li-ion battery safety, particularly with cells that utilize lithium metal anodes, differential scanning calorimetry (DSC) has emerged as a promising technique for the safety analysis of prospective chemistries on a materials scale. DSC is generally used for single materials, single cell layers, and combinations of layers to assess the thermal stability of battery materials as well as the interactions between materials. Despite the common use of DSC in the literature, there is no standardization for sample preparation or reporting requirements to ensure cross-institutional reproducibility. The reaction conditions (e.g., reaction kinetics) present within a DSC sample pan can vary greatly depending on factors such as pan material, pan type, sample loading, and the model/brand of the DSC. These unaccounted-for differences have led to significant variation in DSC results reported in the literature. This makes comparison of results challenging and, perhaps more importantly, modeling efforts using reported DSC data difficult.

In this work, Sandia National Laboratories (SNL) and University of Maryland, College Park (UMD) exchanged and tested lithium metal all-solid-state (LiSSB) materials on each respective DSC platform. UMD utilizes a high-temperature, high-pressure stainless-steel pan on a standard DSC. SNL utilizes an open sapphire pan on a pressurized DSC with no active purge. The results between samples were compared quantitatively and used to determine experimental design factors that can heavily influence results. Using that information, a list of critical experimental parameters was compiled in order to standardize DSC testing, improve cross-institutional reproducibility, and facilitate predictive modeling efforts for battery safety. By carefully controlling the testing conditions of DSC, bounds can be placed on the prediction of large-format cell safety for prospective chemistries which can improve the robustness of early-stage battery safety analysis. This will better guide materials development for next generation chemistries towards fundamentally safer battery materials.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
Efficient Reformulation of Lithium-Ion Battery Models Using Symmetric Polynomials: Extending to Phase Field Models
Authors: Thiagarajan Raghav Sai , Garrick Taylor R. , Subramanian Venkat R.
Published: December 2024

Energy storage will play a crucial role in the transition to clean and renewable sources of energy production to meet future consumption demands. Lithium-ion (Li-ion) batteries are widely adopted due to their high energy density, low self-discharge rate and fast charging capabilities for applications like electric vehicles and grid storage.

Lithium-ion batteries are typically modeled using porous electrode theory coupled with various transport and reaction mechanisms, along with suitable discretization or approximations for the solid-phase diffusion equation.The solid-phase diffusion equation represents the main computational burden for typical pseudo-2-dimensional (p2D) models since these equations in the pseudo r-dimension must be solved at each point in the computational grid. This substantially increases the complexity of the model as well as the computational time. Traditional approaches towards simplifying solid-phase diffusion possess certain significant limitations, especially in modeling emerging electrode materials which involve phase changes and variable diffusivities. A computationally efficient representation for solid-phase diffusion was shown in a previous paper1 based on symmetric polynomials using Orthogonal Collocation and Galerkin formulation (weak form). This approach increases the accuracy of the approximation (p form in finite element methods) to enable efficient simulation with a minimal number of semi-discretized equations, ensuring mass conservation even for non-linear diffusion problems involving variable diffusivities.

These methods will be reviewed for the full p2D model, illustrating their advantages in simulating high C-rates and short-time dynamic operation and extended to newer systems containing phase field models to analyze the robustness of the approximations.

References

R.S. Thiagarajan, A. Subramaniam, S. Kolluri, T. R. Garrick, Y. Preger, 729 V. De Angelis, J.-h. Lim, V. R. Subramanian et al2023 J. Electrochem. Soc. 170 010528
Comparison of Chloride Deposition Rates Measured at a Marine Site Using Dry Candles with Annual, Bi-Monthly and Monthly Exposure Durations
Authors: Sugamoto Ryan , Kealoha Jan , Yamamoto Blake , Hihara Lloyd H.
Published: December 2024

One of the key factors for atmospheric corrosion rates in marine environments is deposition of chloride ions onto metal substrates. Deposition rates are commonly measured using the wet candle or dry plate methods described in standards such as ISO9225 and JIS Z2382. Although the wet and dry methods differ in configuration, analysis for both methods are generally based on monthly exposure intervals. Since deposition rates in marine environments are susceptible to seasonal changes, variations in wave action, and isolated events such as large storms, measurements are conducted throughout the course of a year to obtain a comprehensive evaluation, however, doing so using monthly intervals could be a significant commitment of resources and time for remote sites. This study exposed dry candles, which do not have reservoirs for the wick, and are less sensitive to changes in wind direction compared to dry plates. The dry candles were exposed concurrently with wet candles for 12-month, two-month and monthly intervals at a marine site. Results were examined for correlations between the wet and dry candles, as well as factors such as gauze material, temperature, relative humidity, wind, and wave heights.
Study of Rust Structure Change in Wet and Dry Conditions Using XAFS Measurement
Authors: Ozawa Takahiro
Published: December 2024

Steel products used in social infrastructures such as bridges and tunnels are required to have a long corrosion life for a safe, secure and sustainable society. In general, it is well known that the corrosion behavior of steel varies depending on the corrosive environment, added elements, metallurgy, and rust. In particular, the rust affects corrosion electrochemically, so it is very important to clarify the type and distribution of rusts. Various types of measurement and analysis have been applied to understand the microstructure and distribution of rust layers. In particular, imaging X-ray absorption fine structure (XAFS) is a very effective method for analysis of the generation and growth behavior of rusts that include many amorphous components, because it is possible to measure the valence and bonding distance of iron rusts in two dimensions. Although direct observation of the corrosion progression process by dry-wet cycles has been studied in the past, all of them are limited to structural analysis of only the steel surface under a thin water film in order to suppress the effect of X-ray absorption by the solution. In this study, we attempted in-situ XAFS observation of rust growth and structural change in the depth direction in a dry-wet condition using rusted steel under a controlled water film environment. Rusted steel specimens were corroded by atmospheric exposure, the rust layer was protected by resin coating, and the specimens were thinned to a thickness of about 0.01 mm using a microtome. Imaging XAFS measurements were performed at SPring-8 BL16B2 (SUNBEAM BM) at the same location in the order of pre-test, immersion in salt water, and drying. Noise2Noise, which learns and processes images based on acquired data alone, was used to remove noise from the images, enabling high-resolution analysis. XAFS spectrum were extracted from the denoised data, background removal and normalization were performed. The normalized XAFS spectrum fit the curve obtained by the weighted addition of the spectra for magnetite, goethite and lepidocrocite, and the rust existence state was analyzed from each component and its score value. From the measurement images, the distribution of each rust is clearly observed, and in particular, the amount of Fe3O4 decreases from the steel surface to the surface layer of the rust. In the wet condition, the amount of Fe3O4 increases significantly compared to that in air conditions, and goethite decreases in the vicinity of the steel, while lepidocrocite decreases throughout the rust layer. The reason is assumed to be that oxygen and magnetite react to form goethite and lepidocrocite in the surface layer of the rust, consuming oxygen, and that oxygen does not reach the inner rust layer, causing magnetite to increase as it moves toward the interior.
Electrochemical Conditions to Evalute the Corrosion Fatigue Behavior of Friction-Welded Stainless and Carbon Steel
Authors: Rossi Stefano , Benedetti Luca , Benedetti Matteo , Fontanari Vigilio
Published: December 2024

The aggressive environment significantly influences fatigue-corrosion behavior, reducing material resistance. Welding materials with different electrochemical nobilities proves even more critical due to their particular geometry and the establishment of galvanic couplings. However, the use of joining of dissimilar steels is increasingly necessary to satisfy both corrosion resistance and mechanical properties. The behavior of components and structures working under fatigue in an aggressive environment such as the marine one can be critical.

This study characterized the friction junction between a stainless steel 304L and a carbon steel ASTM A105. A specially designed and constructed electrochemical cell allowed evaluating the fatigue-corrosion behavior of the junction in a 3.5 wt.% NaCl solution, simulating the marine environment, at different electrochemical potentials. To simulate and verify the influence of cathodic protection and overprotection, fatigue-corrosion tests were conducted both in free immersion conditions and at two cathodic potentials equal to -850 mV and -1300 mV Ag/AgCl. The negative role of the aggressive environment and the positive role of cathodic protection were highlighted. The effect of hydrogen developed by the cathodic reduction reaction in overprotection was also evaluated. Failure analyses allowed identifying different degradation mechanisms depending on the different testing conditions.
Comparison of Different Energy Storage Systems for Stationary Applications Based on Real Cases
Authors: Poli Nicola , Trovò Andrea , Marini Giacomo , Guarnieri Massimo
Published: December 2024

Among the different energy storage systems, the electrochemical ones are the most suitable to increase the share of renewable production up to 100%, due to their wide energy and power scalability, site versatility, modularity and ease of use. Few are those available on the market and already used for stationary applications, such as: hydrogen-electrolyzer-fuel cell, lithium-ion, sodium-sulfur and flow batteries [1]. Several studies compare such systems from a technical and economic point of view, but very few are based on real experimental results to show which system provides the best performance in terms of both operation performance and revenues. Thanks to the collaboration with some energy companies that are increasingly interested in the energy storage sector, our goal is to simulate and compare the performance of different energy storage technologies used in real installations over the years in Italy [2-4]. The comparison will not only focus on general parameters such as the cost and the lifetime of the systems, but it will also provide a business analysis to show the actual benefits that each system can bring to costumers. This research aims to provide a comprehensive comparison that can help companies to choose the most appropriate energy storage systems suitable for real needs with a focus on flow battery systems.

References

[1] Trovò A, Rugna M, Poli N, Guarnieri M, Prospects for industrial vanadium flow batteries, Ceramics International 2023 (in press)

[2] Poli N, Trovò A., Fischer P, Noack J, Guarnieri M, Electrochemical rebalancing process for vanadium flow batteries: Sizing and economic assessment J Energy Storage 2023, 58 (106404)

[3] Bovo A, Poli N, Trovò A, Marini G, Guarnieri M, Hydrogen energy storage system in a Multi‒Technology Microgrid:technical features and performance, International J Hydrogen Energy 2023 (in press)

[4] Epoupa Mengou J, Trovò A, Guarnieri M, A vanadium redox flow Battery bracing the pilot microgrid at Eni Renewable Energy & Environmental R&D Center, 2021, 22nd IEEE International Conference on Industrial Technology (ICIT), Valencia, Spain, 2021, pp. 298-303

Figure 1
Corrosion Behavior of Additively Manufactured Mg-1Zn Alloy: Comparative Study between As-Built and Heat-Treated Conditions
Authors: Reyes Raul , Garcia-Galvan Federico R. , Lieblich Marcela , Jiménez José Antonio , Fajardo Santiago
Published: December 2024

Additive Manufacturing (AM) unveils a spectrum of distinctive advantages, including design freedom, minimal waste generation, and energy efficiency compared to traditional manufacturing methods. Laser Powder Bed Fusion (LPBF) is a notable technique within AM, involving the selective deposition and melting of metallic powder layers using a high-powered laser to create three-dimensional parts based on a pre-designed digital model.

Magnesium (Mg), with a density of approximately 1.74 g/cm³, emerges as a promising material in the transportation industry due to its lightweight nature and excellent strength-to-weight ratio. This not only addresses engineering challenges but also provides significant advantages in terms of energy efficiency and the reduction of CO2 emissions, the primary contributor to the greenhouse effect. Moreover, Mg's biocompatible properties offer opportunities for use in the biomedical field, particularly for temporary implant applications. However, the use of Mg alloys is limited by their low ductility and corrosion resistance in aqueous environments

This study investigates the microstructure and corrosion resistance of LPBF-prepared Mg-1Zn alloy in a NaCl solution. Surface analysis, electrochemical measurements including Potentiodynamic Polarization (PDP) and Electrochemical Impedance Spectroscopy (EIS), and gravimetric hydrogen (H2) collection were conducted to assess the alloy's performance. Additionally, the effect of heat treatment was studied. Consequently, two conditions were examined: as-built and heat treated Mg-1Zn.
Repurposing Plastics into Membranes for Redox Flow Batteries
Authors: Diaz Andrea , Zhang Zhongbo , Zhang Lu , Patel Shrayesh N.
Published: December 2024

Solving sustainability grand challenges can be optimally approached through unique innovative approaches to material design and application integration. Membranes play a critical role in redox flow batteries’ cycling performance, optimizing blockage of redox active species while promoting transfer of charge balancing ions. Leading membrane designs are costly, demonstrating opportunity for pathways towards membrane cost reduction through unique material re-design. Here, we have been exploring repurposing commercially available engineered plastics for application for higher value energy storage applications – a strategy towards upcycling. We report the use of aromatic based polymers towards novel membrane design with tunable mesoporous architecture and interconnected nano-sized ion-conducting channels tailored to aqueous redox flow battery (RFB) systems. We fabricate a porous membrane scaffold through a phase inversion technique which is then post-functionalized to give it charge bearing capabilities, demonstrating a good balance between conductivity and perm-selectivity. First generation membrane designs demonstrate notably low area-specific resistance (ASR) in both acidic and alkaline electrolytes. These membranes also demonstrate lower permeance of the redox active species when compared to leading membranes such as NafionTM and when tested in an alkaline system. Moreover, when tested in a cycling flow battery, the membranes can deliver notable capacity retention and power density. In addition, a technoeconomic analysis of these membranes also demonstrates a significant cost decrease when compared to leading RFB membranes. This work suggests exciting opportunities for upcycling non-sustainable plastic waste utilizing a tunable technique to target structure-property-processing of polymers towards mesoporous membranes for energy conversion and storage applications.
(Invited) Materials and Processes Developments for the Commercialization of Perovskite Solar Cells
Authors: Eguchi Naoto , Yamamoto Kohei , Fukazawa Taro , Funaki Takashi , Onozawa-Komatsuzaki Nobuko , Nishimura Naoyuki , Kanda Hiroyuki , Mondal Santa , Kogo Atsushi , Miyadera Tetsuhiko , Miyake Takashi , Murakami Takurou N.
Published: December 2024

Perovskite solar cells (PSCs) can be the lightweight film type of solar cells from their bendable characteristics of the perovskite layers. However, performance improvements are still needed, such as long-term durability and the development of large-area deposition processes for commercialisation.

To this end, we are working on the development of high durability technology and cell manufacturing technology to lead the mass production of perovskite solar cells. We are also working on methods for analysing perovskite solar cells and technology for evaluating their performance and reliability. This presentation will introduce the research and development activities at AIST for the commercialisation of perovskite solar cells.

We would like to thank NEDO for supporting the R&D projects for perovskite solar cells (JPNP21016).
Inorganic Additive-Based Approach for Wide-Bandgap Perovskites and Their Crystallization Mechanism
Authors: Nishikubo Ryosuke , Park Yeon , Saeki Akinori
Published: December 2024

The formation process of lead halide perovskite (LHP) is affected by various components such as composition, additive, under-layer, etc... Those components significantly change the perovskite quality such as crystallinity, defect density, and halide segregation. However, the comprehensive understanding of the correlation between process condition (composition, underlayer, and additive) and charge dynamics is still lacked. Furthermore, the crystallization dynamics with varied process condition are of significant importance to reveal the control strategy of film quality. Herein, charge carrier dynamics of Br-rich wide-bandgap (WG) perovskite was studied using photoluminescence spectroscopy (PL) and time-resolved microwave conductivity (TRMC). Inorganic additive was introduced to suppress trap formation and halide segregation. Although various organic additive have been reported, the study of inorganic additive for WG perovskite are relatively few. The crystal formation dynamics was also studied by originally build in-situ optical spectroscopy.

Varied composition of perovskite (A-site: FA0.8MA0.15Cs0.05, FA0.9Cs0.1, FA0.85MA0.15, X-site: Br 20, 33, 50%) with different under-layer (regular: TiO2, inverted: PTAA/PFN-Br) were prepared, and evaluated. X-ray diffraction measurement demonstrated that 3-cation (FAMACs) exhibits relatively high crystalline size when TiO2 was used as under-layer, whereas 2-cation (FACs) exhibited improved crystallinity when it was deposited on PTAA/PFN-Br. TRMC measurement revealed that FAMACs on TiO2 and FACs on PTAA/PFN-Br exhibits improved charge lifetime. Subsequently, inorganic additive was introduced into FAMACs perovskite with the Br-ratio of 33%. Metal chloride additive exhibited the improvement in TRMC photoconductivity, photovoltaic performance, and stability upon voltage scan. Nucleation and crystallization dynamics was also studied using originally developed in-situ spectroscopy. The significant change of formation dynamics was observed upon changing composition and additives. Our study provides new insight into perovskite film formation and obtained property.

Figure 1
Large-Area Ultrasonic Spray Manufacturing with Open-Air Plasma Curing of Transparent Conducting Oxides for Thin Film Solar Cells with High Figures of Merit via Solution Combustion Synthesis
Authors: Colburn Thomas William , Crane Gabriel , Flick Austin C , Carbone Abigail , Miller Robert D , Dauskardt Reinhold Horst
Published: December 2024

Transparent conducting oxides (TCOs) have remained critically important as electrodes for perovskite solar cells, LEDs, and optoelectronics. Commonly implemented solution-based deposition methods of TCOs such as sol-gel utilize lengthy anneals at temperatures >400 ºC under controlled forming atmospheres which limit high-throughput manufacturing. Sol-gel produced TCOs can also struggle from lower conductivity and lower film density which can inhibit performance as an electrode. As a result, sputtering is commonly used to generate films at the sacrifice of in-line throughput speeds and cost. Solution combustion synthesis overcomes challenges with sol-gel and sputtering by utilizing an exothermic combustion event to generate thin films at impressive speeds from liquid precursors under ambient conditions and with lower required thermal loads.

Here, we present a fully vacuum-free, open-air, and high-speed deposition of large area TCOs via solution combustion synthesis. We utilize four ultrasonic spray printing passes at 6 m/min followed by a 1-minute thermal cure to generate the oxide. Then, we utilize an open-air, 15-minute forming gas plasma anneal to introduce oxygen vacancies. Using this method, we demonstrate the fabrication of 300 cm2 of indium tin oxide with an average Haacke figure of merit (%Tvis
10/Rs) of 0.005 1/ohm, average sheet resistance of 64 +/- 14 ohm/sq and a champion sheet resistance of 38 ohm/sq. We also demonstrate optical transmission of 89% +/- 3% and stability of the films in air for >20 days. In-house cost modeling in collaboration with the National Renewable Energy Laboratory of our TCO fabrication process for a 100 MW perovskite solar module facility demonstrates a >50% reduction in price for the TCO compared with traditional vacuum sputtering. This work is a meaningful step toward a new method for manufacturing TCOs at commercial scales for solar and optoelectronic applications in open-air and reduced costs.
New Perylene Diimide Dyes and Inks for Large Area Roll-Coated Organic Solar Cells
Authors: Welch Gregory Charles
Published: December 2024

Polycyclic aromatic molecules, especially perylene diimide based dyes, are widely used as electronic materials in photovoltaic devices.1 Our team at the University of Calgary has been actively developing modified perylene diimides for use in a range of solution processed electronic devices including organic solar cells,2 organic light emitting diodes,3 transistors and sensors,4 electrochromic films,5 and photo/electro cathodes.6 This presentation will detail the design and synthesis of several classes of modified perylene diimides for specific use in large area organic solar cell devices and modules, primarily as cathode interlayers in both conventional and inverted type cells, but also as non-fullerene acceptors. Structure-property relationships, the formation of functional large area films via slot-die coating using green solvents, and utility both small area devices and flexible modules will be discussed. Applications as indoor light recycling devices and integration into operational greenhouses will be presented.

1 Journal of Materials Chemistry A, 2021, 9 6775-6789

2 Journal of Materials Chemistry C, 2020, 8, 13430-13438

3 Journal of Materials Chemistry C, 2020, 9, 2314-2319

4 Journal of Materials Chemistry C, 2021, 9, 13630-13634

5 Journal of Materials Chemistry C, 2024, 12, 1710-1717

6 Chemical Science, 2022, 13, 1049-1059
(Invited) Development of Fused Porphyrin Sensitizers for Efficient Dye-Sensitized Solar Cells
Authors: Higashino Tomohiro
Published: December 2024

Dye-sensitized solar cells (DSSCs) have attracted considerable attention as an alternative to silicon-based solar cells due to their potential advantages in terms of power conversion efficiency, production cost, design flexibility, and indoor use. Because the photovoltaic performance of DSSCs strongly depends on sensitizers, various kinds of sensitizers have been developed. Among them, porphyrin sensitizers have made remarkable contribution to performance improvement in DSSCs. The push–pull type porphyrin sensitizers have displayed excellent light-harvesting ability and demonstrated high power conversion efficiencies more than 10% in DSSCs.

Meanwhile, incorporation of aromatic-fused structure into a porphyrin core is a fascinating option for highly efficient DSSCs because of direct π-expansion of the porphyrin core and resultant red-shifted absorption. However, aromatic-fused porphyrin sensitizers have suffered rather low cell performances due to their mismatch of HOMO-LUMO levels, high aggregation tendency, and short lifetime of the excited states. Bearing these in mind, we envisioned that the introduction of methylene-bridged fused structure into a porphyrin core would overcome these drawbacks, boosting the cell performance. In this context, we designed and synthesized a series of methylene-bridged thiophene-fused porphyrin sensitizers and revealed that the DSSC of thiophene-fused porphyrin sensitizer achieved the highest power conversion efficiency ever reported for DSSCs with aromatic-fused porphyrin sensitizers. Furthermore, rational molecular design can realize further enhancement of the photovoltaic performance of the DSSCs with thiophene-fused porphyrin sensitizers.
(Invited) Design and Synthesis of π-Conjugated Polymers for High-Efficiency Organic Photovoltaics
Authors: Osaka Itaru
Published: December 2024

Bulk-heterojunction organic solar cells based on π-conjugated polymers as the p-type semiconductor (electron donor) have been intensively investigated in the last few decades since they can enable lightweight, flexible, semi-transparent, low-cost, and low-energy fabrication in contrast to the conventional silicon solar cells. While fullerene derivatives have been used as the n-type semiconductor (electron acceptor), which afford power conversion efficiencies of more than 10% when combined with a narrow-bandgap π-conjugated polymer, recently non-fullerene acceptors having low bandgap have been shown to provide even higher efficiencies over 18% when combined with a wide-bandgap π-conjugated polymer. A key to improving the power conversion efficiency is to control the polymer order as well as the morphology (phase separation) that determines the charge separation and charge transport processes. Therefore, careful molecular design of π-conjugated polymers to manage the backbone coplanarity and intermolecular interactions is imperative. We have been studying a number of π-conjugated polymers by incorporating various heteroaromatics into the polymer backbone. In this presentation, I will show the design and synthesis of new π-conjugated polymers and discuss how the molecular structure affects the polymer order in the thin film and thereby OPV performances.
Stretchable Micro-Supercapacitors Based on Laser Directly Patterned Graphene/Liquid Metal
Authors: Choi Yu Jeong , Ryu Hui Jin , Yang Chanwoo
Published: December 2024

Herein, we fabricate highly deformable micro-supercapacitors (MSCs) based on gallium indium liquid metal (EGaIn) current collectors with integrated graphene. The well-defined interdigitated electrode patterning with controlled gap was successfully realized by using laser ablation technique due to strong laser absorption of graphene and EGaIn. By carefully controlling the gap size between adjacent interdigitated electrodes and the mass loading of graphene, we achieved high areal capacitance (1336 µF/cm2) with reliable rate performance. In addition, due to the intrinsic liquid properties of the EGaIn current collector, the energy storage performance of the MSC maintained 90% of its original areal capacitance even after repeated folding and 20% stretching (1000 cycles). Finally, we successfully integrated the deformable MSC with a commercial light-emitting diode to demonstrate the feasibility of MSC as a deformable power source. The fabricated MSCs operated stably under various mechanical deformations, including stretching, folding, twisting, and wrinkling.
Fluorine-Free Conducting Binder Polymer for Conductive Agent-Free NCM811-Based Lithium Ion Batteries
Authors: Choi Hojun , Jeonghun Kim
Published: December 2024

In this study, we synthesized conductive polymer, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) having high concentration, proper viscosity, and electrical conductivity of 500 S/cm for fluorine-free binder of lithium ion batteries (LIBs) without conductive agents such as super-P, carbon nanotube, and graphene. Only one water-based polymer could act as both a binder and a conductive agent for a high-nickel cathode, NCM811. The aqueous conductive polymer is environment-friendly and processable for fabrication of cathode. However, in an aqueous environment, high-nickel cathode has serious performance degradation such as a decrease in capacity and a corrosion of the current collector. In order to solve this problem, the surface of NCM811 was pretreated with phosphoric acid and the surface treatment process was analyzed and optimized in this study. We report the synthesis of PEDOT:PSS, process for viscose slurry, and their application to fluorine-free conducting binder for high-nickel cathode without conductive agent for LIBs.
(Invited) Control of Elementary Processes in Semiconductor Process Plasmas
Authors: Shiratani Masaharu , Kamataki Kunihiro , Itagaki Naho , Yamashita Naoto , Okumura Takamasa , Koga Kazunori
Published: December 2024

Low-temperature plasma technology is used in as much as 70% of the front-end processes of semiconductor fabrication, including etching, deposition, and surface modification [1-7]. In this talk, I focus on the importance of controlling elementary processes in semiconductor process plasmas. First of all, the choice of source gas is important. In hard carbon thin film deposition, for instance, the higher the C/H in the film, the harder the film tends to be. Therefore, it is easier to achieve a higher degree of hardness by using C2H2 as the raw material gas rather than CH4, which has a lower C/H. If the raw material molecules contain benzene rings, the benzene rings are more easily incorporated into the films, and the C/H tends to be lower. Next, it is important to select the type of radicals produced by electron impact dissociation of the source gas; in the case of CH4, four types of radicals, CH3, CH2, CH, and C, are produced by electron impact dissociation. The surface sticking probability is small for CH3 and large for C. To deposit films with high step coverage on complexly shaped surfaces such as trenches, it is desirable to use CH3, which has a small surface sticking probability, as the main precursor for film deposition. These two different directions make it difficult to form hard carbon thin films in trenches with a high step coverage. Therefore, other avenues are to be explored. One such approach is control of elementary processes by unconventional plasma generation, which includes pulsed plasmas, amplitude-modulated RF discharge plasmas, and arbitrary waveform excitation plasmas. In short, elementary process control is the key to success in low-temperature plasma technology.

Acknowledgements: This work was partly supported by JSPS KAKENHI (Grant Nos. JP20H00142, JP21H01372, JP21K18731, and JP23K03368), the JST ASPIRE, the NTT collaborative research, and the Murata Science Foundation.

[1] M. Morimoto, et al., Jpn. J. Appl. Phys. 62 (2023) SN1001.

[2] K. Kamataki, et al., Mater. Sci. Semicond. 164 (2023) 107613.

[3] M. N. Agusutrisno, et al., Mater. Sci. Semicond. 162 (2023) 107503.

[4] R. Narishige, et al., J. Mater. Res. 38 (2023) 1803.

[5] N. Yamashita, et al., J. Mater. Res. 38 (2023) 1178.

[6] I. Nagao, et al., Mater. Adv. 7 (2022) 918.

[7] S. H. Hwang, et al., Processes., 9 (2020) 2.
(Invited) Impact of CMOS Miniaturization on Digital and RF Applications and Its Future
Authors: Iwai Hiroshi
Published: December 2024

Semiconductors, especially CMOS LSIs (Complementary Metal-Oxide-Semiconductor Large-Scale Integrated Circuits), are fundamental to our contemporary highly intelligent society, exemplified by technologies like artificial intelligence (AI). The exceptional performance and functionality of current CMOS LSIs are largely attributed to the ongoing miniaturization of their core components: MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors). Since the inception of MOS LSI production in the early 1970s, MOSFETs have undergone regular size reductions every 2 to 3 years. The minimum linewidth, which was 10 μm in 1970, has now shrunk to nearly one-thousandth of that size, approaching 10 nm. Each phase of MOSFET miniaturization has encountered formidable technological challenges, overcome through innovative solutions.

However, we stand at a critical juncture. The relentless drive toward smaller MOSFETs is now approaching physical limits. The future trajectory of CMOS LSIs will veer away from further miniaturization and instead focus on channel stacking—a strategy to sustain progress. In this presentation, I delve into the history of CMOS LSI miniaturization, explore its impact on digital information processing and RF communication applications, and gaze into the post-miniaturization era, anticipating both opportunities and challenges.
Contact Resistance Reduction of MoS2-Based Field Effect Transistor Using Semimetallic TiS2 Contact Layer Deposited By Atomic Layer Deposition
Authors: Seo Jeongwoo , Yoon Hwi , Lee Sangyoon , Sohn Inkyu , Kim Hyung-jun , Chung Seung-min , Kim Hyungjun
Published: December 2024

Recently, two-dimensional transition metal dichalcogenides (2D TMDCs) have been researched as promising channel materials for filed effect transistors (FETs) owing to their high mobility at atomic-level thickness. As miniaturization and high performance of the electronic devices are required, however, high contact resistance at the interface between the metal electrode and 2D TMDC channel has become a major challenge.1

The high contact resistance at the metal-semiconductor interface originates from the uncontrollable high Schottky barrier height (SBH). Due to Fermi-level pinning induced by metal-induced gap state (MIGS) and defect-induced gap state (DIGS), the barrier height cannot be controlled by conventional Schottky-Mott rule, regardless of metal work function. Since MIGS occurs due to perturbation of metal wave function into the semiconductor, inserting semimetallic material as contact layer can be a solution to suppress the MIGS and further reduce the contact resistance.2

In this study, ALD TiS2 was used as semimetallic contact layer between the MoS2 channel and Ti/Au electrode for MoS2-based TFT. With the TiS2 contact layer, we could observe improvements in overall device performances, which is attributed to the semimetallic nature of TiS2. In addition, low temperature ALD TiS2 process contributed to the clean interface with vdW bonding between MoS2 and TiS2, resulting in suppression of DIGS, as well as MIGS. Owing to the ALD TiS2 contact, we could mitigate FLP and achieve metal-semiconductor interface with low Schottky barrier height, resulting in low contact resistance.

References

1 K. Schauble et al., “Uncovering the effects of metal contacts on monolayer MoS2,” ACS Nano, vol. 14, no. 11, pp. 14798–14808, 2020, doi: 10.1021/acsnano.0c03515.

2 P. C. Shen et al., “Ultralow contact resistance between semimetal and monolayer semiconductors,” Nature, vol. 593, no. 7858, pp. 211–217, 2021, doi: 10.1038/s41586-021-03472-9.
Influence of Nanoscale Dielectric Gap on Electrical Characterization in Scanning Probe Microscopy
Authors: Eom Seongmun , Kavle Pravin , Kang Deokyoung , Kim Yeongyu , Martin Lane W. , Hong Seungbum
Published: December 2024

Scanning Probe Microscopy (SPM) techniques, including Conductive-Atomic Force Microscopy (C-AFM), Kelvin Probe Force Microscopy (KPFM), and Piezoresponse Force Microscopy (PFM) or Electrochemical Strain Microscopy (ESM), are critical for the in situ, non-destructive analysis of material interfaces with high spatial resolution. Despite substantial advancements in SPM technologies, challenges related to their reliability and accuracy remain, primarily due to measurement artifacts and electrochemical reactions on the sample surface. These artifacts can significantly skew results, leading to misconceptions unless critically analyzed.

This study explores the influence of the dielectric gap on electric characterization, particularly focusing on how variations in permittivity affect the results obtained from C-AFM and PFM techniques. By adjusting the permittivity of the dielectric medium (air, water with εr = 79, and silicone oil with εr = 2.1-2.8), we demonstrate that high permittivity media can significantly correct the discrepancies commonly observed in coercive field measurements, aligning them closer to values obtained from conventional capacitor-based polarization methods.

Our findings illuminate the critical role of the dielectric gap in SPM, suggesting methodological adjustments for improved accuracy in the nanoscale electrical characterization of electrochemical materials. These insights offer significant implications for advancing the precision and reliability of SPM techniques in studying electronic materials.
(Invited) Na-Ion Battery: Towards Sustainable Layered Oxide Cathodes
Authors: Li Xiaolin , Omenya Fredrick , Lucero Marcos , Reed David M
Published: December 2024

Na-ion batteries with layered oxide cathodes have similar rocking chair working mechanism to Li-ion batteries and are promising for grid energy storage and electric vehicles. The option of P2 and O3 structures provides excellent flexibility in material design for high performance and material sustainability. In our journey of sodium-ion battery development at Pacific Northwest National Laboratory, we demonstrated the viability of the technology using high-Ni layered oxides and have developed various types of layered oxides towards low-cost cathodes with reduced amounts of critical materials. Fading mechanisms of these materials in the bulk structures and at the interfaces also are investigated. In this talk, I will reveal our effort on both fundamental understanding of the cathode material design and practical research on the material scaleup and pouch cell fabrication.
(Invited) Recent Developments in Lithium-Manganese-Oxide Electrochemistry
Authors: Thackeray Michael M. , Tornheim Adam P. , Vu Anh D. , Shi Boyu , Lee Eungje , Croy Jason R.
Published: December 2024

There has been a concerted effort over the past several years to design and develop manganese-rich lithium-metal-oxide cathodes for the lithium-ion battery industry. The prime motivation for this endeavor is to identify more cost effective and high energy electrode materials that can compete with today's Ni-rich (NMC) and LiFePO4 (LFP) systems. This presentation will cover recent developments at Argonne National Laboratory, highlighting the progress made in developing, characterizing and understanding disordered rocksalt- and lithiated-spinel electrode materials with a high manganese content, with a particular focus on cobalt-free systems.