bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stretching Compensation Pixel Circuit Based on Oxide Thin Film Transistor
Authors: Kim Seo Gwon , Kang In Hye , Kang Seok Jun , Woo Jae Geun , Bae Byung Seong 
Published: December 2020

Thin film transistors (TFTs) are the essential elements to implement active matrix organic light-emitting diode (AMOLED) display. The TFT on the AMOLED controls the emission of the OLED. Pixel circuits are being studied to improve the display quality. Poly-crystalline silicon TFT and oxide TFT have been manufactured and integrated on glass substrates for AMOLED. Various kinds of display such as foldable, rollable, wearable and stretchable displays are being studied.
In stretchable displays, the device and wires manufactured on the substrate are stretched out. The resistances of wire, parasitic capacitances are affected by stretching of the substrate. In addition, when the substrate is stretched, electrical characteristic such as threshold voltage and mobility of TFT would be able to change, which results in the luminance change of the OLED. Therefore, analysis of changes in TFT is required when the substrate is stretched, and compensation circuits are required. In this study, the compensation pixel circuit is proposed for the stretchable display.
To make the circuit, IGZO was used as an active layer of the TFT and deposition by RF magnetron sputter. Insulator layer was deposited for the gate insulator using atomic layer deposition (ALD) and inter layer dielectric was formed after doping of the source-drain region in the same way after doping of the source-drain region.
WSe2 Homogeneous in-Plane Pin Junction Diode with Electric Double Layers
Authors: Choi Wonjun , Ahn Jongtae , Im Seongil , Jeong Yeonsu 
Published: December 2020

Transition metal dichalcogenide (TMDC) materials are in the spotlight as next-generation semiconductor materials because of their advantages over other semiconductor materials. Research on WSe2 among the materials is underway, and the feature of WSe2 has an ambipolar characteristic, and the fermi level change and the doping effect are different according to the electrode type.
In the present study, we have fabricated a homogeneous WSe2 PIN junction diode. Our in-plane multilayer WSe2 p-i-n homogeneous diode exhibited photovoltaic properties by asymmetric physical contact doping effect with electric double layer(EDL). Owing to the EDL placed between the cathode and anode, local charge carrier type and density profile are modulated in the same layers.
Compared to general diode mode, PIN mode enhance the photo response of the device in our visible measurement range. The diode exhibits excellent rectifying behavior with a current rectification ratio of 104 or higher. Photovoltaic performance of short circuit current and open circuit voltage achieved 3.2 nA, 0.55 V, respectively under the 550 nm green light. And spectrum responsivity is about ~100 mA/W (max point) at 3.2 eV to 1.6 eV.

Figure 1
(Invited) Liquid Phase Interfacial Assemblies of Porous Nanosheets with Controlled Orientation and Thickness
Authors: Makiura Rie 
Published: December 2020

Development of rational methods for creating ordered two-dimensional (2D) structures with nanometer scale precision is one of the central issues in the nanoscience and nanotechnology fields because of their intrinsic physical-chemical properties which are seen in those of their equivalent bulk state. Inclusion of highly regulated nanopores into the nanosheet structure will further open the possible applications such as nanosieves, molecular/ion storage and sensor devices as well as introducing guest molecules into the nanopores tune variedly the sheet properties (electric conduction, nanoheterojunction). Utilizing molecular building units are suitable for creating such porous nanosheets because of rich variety of design and facile modification of size and shape. Furthermore, various chemical interactions such as covalent bond, coordination and hydrogen bond are applied for assembling molecular-based nanosheets.
Here, I present a facile bottom-up synthesis of molecular nanosheets with both positional and size regulated nanopores utilizing air/liquid interfaces. By applying liquid interfaces, growth direction of the object can be well controlled with utilizing self-assembly feature of the molecules under mild conditions. We have succeeded to tune finely the nanosheet structures by rational modification of molecular building units [1-4]. In addition, new methodology we developed based on the liquid interface technique resulted in enlarging the nanosheet size. The highly crystalline structure remains after transferring a solid substrate from the liquid surface as well as without any supports. Notably, such highly oriented porous crystalline structure is obtained specifically by applying bottom up synthesis at air/liquid interfaces, not by other techniques such as drop cast [5].

Makiura, R. et al. Nature Mater. 9, 565 (2010).

Motoyama, R. Makiura, O. Sakata, H. Kitagawa, J. Am. Chem. Soc. 133, 5640 (2011).

Makiura, R., Konovalov, O. Rep. 3, 2506 (2013).

Makiura, R. et al. ChemPlusChem. 79, 1352 (2014).

Makiura, R. et al. ACS Nano,
11, 10875–10882 (2017).

Figure 1
(Keynote) Functional 2D Conjugated Polymers By Interfacial Synthesis
Authors: Dong Renhao 
Published: December 2020

The discovery of graphene one decade ago has triggered enormous interest in developing chemistry of synthetic two-dimensional materials (2DMs). In our work, we have employed interfacial chemistry toward the controlled synthesis of organic 2DMs with diverse structures and functions.[1] For instance, we demonstrated the synthesis of 2D conjugated metal-organic framework (2D c-MOF) at the air-water or liquid-liquid interfaces. The 2D c-MOFs feature with stacked layers and possess unique electronic properties, such as full π delocalization, narrowed band gaps, high conductivity and high mobility, which render 2D c-MOFs as advanced electronic materials. One representative iron-bis(dithiolene) 2D MOF exhibited as a p-type semiconductor with a band-like transport and high mobility of ~220 cm2/Vs.[2] Owing to their conductivity, the 2D c-MOFs have shown potential for transistors, photodetectors, sensing, magnetics, and energy storage and conversion.[1,3,4] Besides the coordination polymer, we have also synthesized conjugated 2D covalent polymers at the air-water or liquid-liquid interfaces. In our latest work, we have employed a surfactant-monolayer-assisted interfacial synthesis (SMAIS) method to prepare 2D polymers, like 2D polyimides and 2D polyimines, which exhibit few-layers and micrometer-sized single-crystalline domains.[5] In short, we expect to develop interfacial chemistry methodologies toward the controlled synthesis of organic 2DMs and achieve delineation of reliable structure-property relationships and superior physical and chemical performances of organic 2DMs.
References
[1] R. Dong, et al., Chem. Rev. 2018, 118, 6189-6235.
[2] R. Dong, et al., Nat. Mater. 2018, 17, 1027-1032.
[3] a) R. Dong, et al., Nat. Commun. 2018, 9, 2637; b) C. Yang, et al., Nat. Commun. 2019, 10, 3260.
[4] H. Zhong, et al., Angew. Chem. Int. Ed. 2019, 58, 10677-10682.
[5] K. Liu, et al., Nat. Chem. 2019, 11, 994-1000.
(Invited) Atomic Layer Deposition of MOF from Dissolved Precursors ― ‘Solution ALD’ (sALD)
Authors: Barr Maissa K. S. , Nadiri Soheila , Chen Dong-Hui , Weidler Peter G. , Baumgart Helmut - , Redel Engelbert , Asker Ceyla , Forberich Karen , Hoga Felix , Stubhan Tobias , Egelhaaf Hans , Brabec Christoph , Bachmann Julien 
Published: December 2020

Metal organic frameworks (MOFs) are crystalline three-dimensional porous solids featuring a high surface area, which have attracted considerable attention in a wide range of applications e.g. in catalysis, hydrogen storage, gas separation, thermoelectric applications or as chemical sensors. Beyond solvothermal synthesis of bulk MOF crystals, growing MOFs thin films has been limited so far to rather conventional solution-based techniques. However, traditional growth methods from solution such as spin-coating, spray-coating or dip-coating generate MOFs thin films with a rather low film quality and an alarming lack of a precise film thickness control under 1 nm. This renders them unsuitable for most industrial applications and severely limits their future application potential.
Atomic layer deposition (ALD) provides this capability, but is limited by the necessity to use gaseous precursors in vacuum conditions at temperatures typically above 100°C. This is incompatible with the typically high temperature sensitivity of many hybrid metal-organic compounds such as the MOFs.
In this perspective, we have transferred the principles of ALD to precursors dissolved in liquid solvents. The ‘solution ALD’ (sALD) method can be implemented in a variety of microfluidic or slot-die processing devices. We have demonstrated that the principles of classical, gas-based ALD —self-limiting surface reactions— are reproduced in sALD. sALD shares the fundamental properties of standard ‘gas ALD’ (gALD), in particular the self-limiting surface chemistry and the ability to coat deep pores in a conformal manner Furthermore, sALD allows the experimentalist to design new, advantageous, reactions of known semiconductors (oxides, heavier chalcogenides), or to deposit materials otherwise inaccessible to ALD altogether, such as polymers, ionic solids, and metal-organic frameworks. They may be obtained in highly pure, crystalline form at room temperature, either as planar films or as conformal coatings of porous substrates. Based on these advances, we have been able to make the first sALD-derived films of a MOF, Cu-BDC. At any chosen thickness, sALD MOF films feature significantly lower roughness and better adhesion than those generated by the best spray-coating and dip-coating methods available currently.
Fabrication of Amorphous SRVOX-Based Memristor for Neuromorphic Computing
Authors: Lee Tae-Ju , Kim Su-Kyung , Seong Tae-Yeon 
Published: December 2020

Because resistive random access memory (RRAM) has advantages, such as fast switching speed, low energy consumption, and simple device structure, it is promising device architecture for memory, artificial intelligence, and neuromorphic computing. In particular, for RRAM for use in neuromorphic applications, it must be able to mimic synaptic behavior by pulse modulation. In order to have such a characteristic, the resistance state has to be gradually changed by the stress, e.g., potentiation and depression. High linearity is required because the linearity of RRAM obtained through each resistance state is evaluated as an especially important property for artificial synaptic applications.
In this work, we performed the electrical properties of sputter-deposited amorphous strontium vanadate (a-SVO) RRAM with Pt bottom electrode and Ag top electrode. Sufficient reproducibility and uniformity between devices was realized. The highest resistance ratio of ~ 103 was observed and insignificantly changed for retention testing up to 2 × 104 s. In particular, the conduction filament generated from the a-SVO RRAM was adjusted according to the regulation of voltage stress to obtain a multi-level resistance state. It was confirmed by ToF-SIMS analysis and COMSOL Multiphysics simulation that the conduction filament was formed by Ag atoms. Hopfield Neural Network simulation was conducted to verify that the performance of analog resistive switching behavior of a-SVO RRAM is suitable for neuromorphic computing. The accuracy of our simulated device was saturated to 86.8 % for 100,000 asynchronous iterations. The results imply that our a-SVO RRAM is of great potential for use in neuromorphic computing.
Electrochemical Manipulation of the Electron Transports of SrCoO
x
Epitaxial Films
Authors: Yang Qian , Cho Hai Jun , Jeen Hyoungjeen , Ohta Hiromichi 
Published: December 2020

Strontium cobaltite (SrCoO
x
) has attracted increasing attention as the active material for novel electrochemical memory devices [1-3] because its optical, electrical, and magnetic properties can be controlled electrochemically. Especially, the redox reaction between SrCoO2.5 and SrCoO3 is important because one can control from antiferromagnetic insulator to ferromagnetic metal. In order to utilize this redox reaction as a practical memory device, the macroscopic phenomenon must be clarified. Here, thermopower analysis is used to clarify the electrochemical oxidation macroscopically. A 6-nm-thick GDC (10 mol% Gd-doped CeO2) film was heteroepitaxially grown on (001) YSZ substrate followed by the growth of ~40-nm-thick SrCoO2.5 by pulsed laser deposition. The out-of-plane XRD patterns of the resultant films showed that the SrCoO2.5 were heteroepitaxially grown on the GDC/YSZ with the epitaxial relationship of (001) [100] SrCoO2.5 || (001) [110] GDC/YSZ. We then deposited Pt electrode on the backside of the YSZ substrate and applied current into the film as schematically shown in Fig. a with -5 or -10 V at 300 °C in air. In order to measure the electron transports of the intermediate state, we suspended the electrochemical oxidation several times. From the XRD analyses of the films, we clarified that the conversion rate from SrCoO2.5 brownmillerite to SrCoO3 perovskite could be controlled electrochemically. Although the resistivity (Fig. b) of SrCoO2.5 film was high (5.5 Ω cm), the resistivity dropped after slight oxidation due to the parallel electronic circuit composed of very low resistive SrCoO3 (0.35 mΩ cm). Furthermore, the thermopower (Fig. c) dropped from 70 μV K-1 to ~0 μV K-1 after slight oxidation. A steep decrease in both resistivity and the absolute value of thermopower of electrochemically oxidized SrCoO
x
epitaxial films indicates the columnar oxidation firstly occurred along the oxidation direction and then spread perpendicular to the oxidation direction. This macroscopic image of the electrochemical oxidation would be useful for developing a functional device utilizing the electrochemical redox reaction of SrCoO
x
.
[1] N. Lu et al., Nature
546, 124 (2017).
[2] T. Katase et al., Adv. Electron. Mater. 2, 1600044 (2016).
[3] Q. Lu et al., Nano Lett.
16, 1186 (2016).
[4] Q. Yang et al., Adv. Mater. Interfaces
6, 1901260 (2019).

Figure 1
Development of Electrochromic Device with Poly(3,4-ethylenedioxythiophene) on Invisible Silver-Grid Transparent Electrode
Authors: Kawabuchi Miyuki , Tsuneyasu Shota , Hashimoto Natsuki , Ohsawa Masato , Satoh Toshifumi 
Published: December 2020

Electrochromic (EC) reaction is defined as a reversible color change which induced by the electrochemical redox reactions. The EC device is promising as an optical modulation device such as a display and a window. However, a flexibilities of the EC device is unsatisfied because conventional EC device consists of transparent conductive oxide on the glass substrate. To overcome this, we have developed a gravure offset printed invisible Ag-grid transparent electrodes by using Ag-nanoparticles ink,[1] and demonstrated that a powder electroluminescent device by this transparent electrode showed the high bending stability.[2], [3] Therefore, it is also expected the realization of EC device showing high bending durability.
In this study, the novel EC device composed of poly(3,4-ethyenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) has been fabricated on a gravure offset printed fine Ag-grid transparent electrode and evaluated optical and electrochemical properties. Scanning the potential from 0 V (vs. Ag/Ag+) to the negative direction, the cathodic current due to the reductive reaction of PEDOT:PSS was observed, and the absorbance correspond to the coloration of PEDOT:PSS was increased. Then, when scanning the potential to the positive direction, the anodic current due to the oxidative reaction of PEDOT:PSS was observed, and the absorbance was decreased. This changing in the absorbance were observed several tens of times. These evaluation results demonstrate that PEDOT:PSS develops a reversible color change with the EC reaction on the fine silver-grid transparent electrode.

Reference

[1] M. Ohsawa, N. Hashimoto, Mater. Res. Express, 5, 085030 (2018).
[2] N. Takeda, S. Tsuneyasu, K. Yanagawa, N. Hashimoto, M. Ohsawa, T. Satoh, Electron. Lett., in press.
[3] M. Ohsawa, N. Hashimoto, N. Takeda, S. Tsuneyasu, T. Satoh, Flex. Print. Electron. (under review).

Figure 1
Effect of Specific Surface Area of Counter Electrode in Hybrid Capacitor Type Electrochromic Device
Authors: Liang Zhuang , Nakamura Kazuki , Kobayashi Norihisa 
Published: December 2020

We have already reported a novel hybrid capacitor multicolor electrochromism (EC) in a single device by introducing a porous capacitive counter electrode, ITO particle-modified electrode.1 Due to the formation of the electrical double layer on the counter electrode successfully compensated the charge consumption of EC reaction enables certain colors to be represented selectively both anodic and cathodic EC molecules by just using two electrodes and sandwiched electrolyte. In our another paper, we also found that the capacitance has a greater impact on the appearance of multiple colors.2 Beyond those, in practical EC applications, the performance of coloration, response time also play very important roles. In this regard, the effect of the increase of specific surface area of counter electrode on the EC properties of the hybrid capacitor ECD has not been studied in detail.
In this paper, we fabricated several ECDs having hybrid capacitor structure with flat ITO electrode as the working side and ITO particle-modified electrodes which having different thickness (aim to increase the specific surface area) as the counter side. As the EC molecule, we employed the molecule of 10-methylphenothiazine (MPT). We discussed the effect of increased specific surface area of the counter electrode on the EC properties in the hybrid capacitor ECD.
We measured the capacitance of the ITO particle-modified electrodes having different thickness. Fig. 1 shows the relationship between electrostatic capacitance and thickness of ITO particle-modified electrodes. From the result, we can clearly know that with the increase of thickness, the capacitance showed an increasing trend.
Fig. 2 shows the transmission spectra of the ECDs under application of positive voltage of 1.2 V for 10 s. The transmittance of ECDs decreased strongly due to oxidized MPT molecule appeared at around 515 nm. As the result, color of ECDs changed from transparent state to pink color. At the same driving condition, with the increase of thickness, the amount of charge consumed by EC reaction increased, leading to more obvious ΔT. This result can be explained that with the larger capacitance due to increased specific surface area leading to larger accumulation of electrical charge on the counter electrode, oxidative reaction of the MPT was promoted on the working electrode, toward increased density of pink color.
References
[1] Z. Liang, M. Yukikawa, K. Nakamura, N. Kobayashi, Phys. Chem. Chem. Phys., 2018, 20, 19892–19899.
[2] Z. Liang, K. Nakamura, N. Kobayashi, Sol. Energy Mater. Sol. Cells, 2019, 200, 109914-109921.

Figure 1
Microporous Layer Water Saturation Determination By Sub-Voxel X-Ray Computed Tomography
Authors: Chen Yen-Chun , Liu Wenmei , Berger Anne , De Angelis Salvatore , Schmidt Thomas J. , Buechi Felix N. 
Published: December 2020

A microporous layer (MPL) is typically added to gas diffusion layers in polymer electrolyte fuel cells (PEFC) to enhance fuel cell performance and water management. The related transport mechanisms are not completely understood and therefore characterization is required. However accurate determination of MPL liquid water saturation has not yet been broadly addressed, except for preliminary work.
We demonstrate that X-ray computed tomography (XCT) is suitable and efficient in characterizing MPL’s local liquid water saturation in an ex situ model experiment setup. Our image evaluation pipeline was first developed on porous polymeric membrane materials, validated by independent gravimetric measurements. Mercury intrusion porosimetry (MIP) on MPL further justifies the efficacy of the method. The pipeline has indicated an accuracy of ca. ±7% and a field of view of 6 mm, which suits differential cell investigations. The linear relationship of greyscale value (GSV) and linear attenuation coefficients is shown to hold even for a polychromatic radiation source. This methodology has the potential to accurately characterize the water saturation in MPLs under operando PEFC conditions.
Mapping of Heterogeneous Catalyst Degradation in Polymer Electrolyte Fuel Cells
Authors: Cheng Lei , Khedekar Kaustubh , Rezaei Talarposhti Morteza , Perego Andrea , Metzger Michael , Kuppan Saravanan , Stewart Sarah , Atanassov Plamen , Tamura Nobumichi , Craig Nathan , Zenyuk Iryna V. , Johnston Christina 
Published: December 2020

Durability of cathode catalyst in polymer electrolyte fuel cells (PEFCs) is a key factor, limiting large-scale commercialization of PEFC for transportation applications. The catalyst degradation occurs during operational load profiles switches from ideal to peak, where multiple operational factors affect the degradation rate. The catalyst degrades heterogeneously as the catalyst particles are exposed to local variations throughout the entire catalyst layer during operation. State-of-the-art analytical techniques for studying degradation of Pt catalyst do not possess fine spatial resolution to elucidate such non-uniform degradation behavior at a large electrode level.
We report a new methodology to spatially resolve and quantify the heterogeneous Pt catalyst degradation over a large area (several cm2) of aged MEAs based on synchrotron X-ray micro-diffraction. PEFC samples were aged using voltage cycling as an accelerated stress test. The heterogeneity of catalyst degradation at a micrometer length scale was visualized by mapping Pt catalyst particle size after voltage cycling between 0.6V and open circuit potential. We demonstrated in details that the Pt catalyst particle size growth was non-uniform and followed the flow field geometry. The Pt particle size growth was greater in the area under the flow field land, while it was minimal in the area under the flow field channel. Additional non-uniformity was observed with the Pt particle size increasing more rapidly at the gas outlet area of than the Pt particle size at the inlet area.

Figure 1