Unraveling the Photovoltage Formation Mechanism in Indium-Tin Oxide Branched Nanowires/Poly(3-Hexylthiophene) Photorechargeable Supercapacitors.

Photorechargeable supercapacitors are promising next-generation renewable energy storage devices. Previously, a hybrid structure consisting of indium-tin oxide branched nanowires (ITO BRs) and poly(3-hexylthiophene) (P3HT) was demonstrated as a photorechargeable supercapacitor. However, the formation mechanism of photovoltage has not been studied.

Design of highly transparent ohmic contact to N face n-GaN for enhancing light extraction in GaN-based micro LED display.

In GaN-based vertical micro LEDs, conventional metal n-contacts on the N face n-GaN suffer from a low aperture ratio due to the high reflection of metals, resulting in low-light extraction efficiencies. Great efforts have been devoted to enhancing transparency by employing transparent conducting oxides for n-contacts, but they exhibited poor Ohmic behavior due to their large work functions. Herein, we introduce an InN/ITO n-contact to achieve both superior contact property and high transparency.

LEGO-like Assembly of Fibrous Modules for Display Textiles.

Due to their promising advantages over classical rigid devices, the development of display textiles has exciting potential for various fields, including sensor technology, healthcare, and communication. To realize display textiles, it is necessary to prepare light-emitting building blocks at the fiber level and then weave or knit them to form the desired textile structures. However, from a practical viewpoint, it is difficult to continuously weave functional fibers containing light-emitting devices using conventional textile technologies.

Combination of an inject-and-transfer system for serial femtosecond crystallography.

Serial femtosecond crystallography (SFX) enables the determination of room-temperature crystal structures of macromolecules with minimized radiation damage and provides time-resolved molecular dynamics by pump-probe or mix-and-inject experiments. In SFX, a variety of sample delivery methods with unique advantages have been developed and applied. The combination of existing sample delivery methods can enable a new approach to SFX data collection that combines the advantages of the individual methods.

Water Washable and Flexible Light-Emitting Fibers Based on Electrochemiluminescent Gels.

Herein, a new concept of device architecture to fabricate fibrous light-emitting devices is demonstrated based on an electrochemiluminescence (ECL) material for an electronic textile system. A unique feature of this work is that instead of conventional semiconductor materials, such as organics, perovskites, and quantum dots for fibrous light emitting devices, a solid-state ECL electrolyte gel is employed as a light-emitting layer. The solid-state ECL gel is prepared from a precursor solution composed of matrix polymer, ionic liquid, and ECL luminophore.

Photonic Encryption Platform Dual-Band Vectorial Metaholograms in the Ultraviolet and Visible.

Metasurface-driven optical encryption devices have attracted much attention. Here, we propose a dual-band vectorial metahologram in the visible and ultraviolet (UV) regimes for optical encryption. Nine polarization-encoded vectorial holograms are observed under UV laser illumination, while another independent hologram appears under visible laser illumination.

Completely Hazy and Transparent Films by Embedding Air Gaps for Elimination of Angular Color Shift in Organic Light-Emitting Diodes.

Red, green, and blue top-emission organic light-emitting diodes (RGB TOLEDs) suffer from white color change with viewing angle due to the microcavity effect, called white angular dependence (WAD). Great efforts are devoted by applying various kinds of hazy films, but they suffer from poor mechanical stability and optical transmittance. Herein, we introduce an air-gap-embedded hazy film (AEHF) to solve these problems and suppress WAD in RGB TOLEDs.

CuS-Decorated GaN Nanowires on Silicon Photocathodes for Converting CO Mixture Gas to HCOOH.

Hybrid materials consisting of semiconductors and cocatalysts have been widely used for photoelectrochemical (PEC) conversion of CO gas to value-added chemicals such as formic acid (HCOOH). To date, however, the rational design of catalytic architecture enabling the reduction of CO gas to chemical has remained a grand challenge. Here, we report a unique photocathode consisting of CuS-decorated GaN nanowires (NWs) integrated on planar silicon (Si) for the conversion of HS-containing CO mixture gas to HCOOH.

Photonic Multilayer Structure Induced High Near-Infrared (NIR) Blockage as Energy-Saving Window.

Energy-saving window that selectively blocks near-infrared (NIR) is a promising technology to save energy consumption. However, it is hard to achieve both high transmittance in visible light and high reflectance in NIR for the energy-saving windows. Here, a TiO /Ag/TiO /SiO /TiO multilayer is demonstrated on a glass substrate to selectively block NIR while maintaining high transmittance to visible light.

Indium Tin Oxide Branched Nanowire and Poly(3-hexylthiophene) Hybrid Structure for a Photorechargeable Supercapacitor.

We report a photorechargeable supercapacitor that can convert solar energy to chemical energy and store it. The supercapacitor is composed of indium tin oxide branched nanowires (ITO BRs) and poly(3-hexylthiophene) (P3HT) semiconducting polymers. ITO BRs showed electrical double layer capacitive characteristics that originated from the unique porous and self-connected network structure.

Grain Boundary Engineering of Cu-Ag Thin-Film Catalysts for Selective (Photo)Electrochemical CO Reduction to CO and CH.

We investigated the relationship between grain boundary (GB) oxidation of Cu-Ag thin-film catalysts and selectivity of the (photo)electrochemical CO reduction reaction (CO RR). The change in the thickness of the Cu thin film accompanies the variation of GB density, and the Ag layer (3 nm) has an island-like morphology on the Cu thin film. Therefore, oxygen from ambient air penetrates into the Cu thin film through the GB of Cu and binds with it because the uncoordinated Cu atoms at the GBs are unstable.

Highly transparent all-dielectric metasurface to block the near-infrared region of the solar spectrum.

Blocking the near-infrared region (NIR) is indispensable for saving energy consumed to maintain the interior temperature in buildings. However, simultaneously enhancing transmission in visible light and blocking in the NIR remains challenging. Here, we theoretically demonstrate a transparent all-dielectric metasurface selectively blocking the NIR by using TiO nanocylinders and an indium tin oxide (ITO) layer.

Abnormal dewetting of Ag layer on three-dimensional ITO branches to form spatial plasmonic nanoparticles for organic solar cells.

Three-dimensional (3D) plasmonic structures have attracted great attention because abnormal wetting behavior of plasmonic nanoparticles (NPs) on 3D nanostructure can enhance the localized surface plasmons (LSPs). However, previous 3D plasmonic nanostructures inherently had weak plasmonic light absorption, low electrical conductivity, and optical transmittance. Here, we fabricated a novel 3D plasmonic nanostructure composed of Ag NPs as the metal for strong LSPs and 3D nano-branched indium tin oxide (ITO BRs) as a transparent and conductive framework.

AlGaN Deep-Ultraviolet Light-Emitting Diodes with Localized Surface Plasmon Resonance by a High-Density Array of 40 nm Al Nanoparticles.

We present a remarkable improvement in the efficiency of AlGaN deep-ultraviolet light-emitting diodes (LEDs) enabled by the coupling of localized surface plasmon resonance (LSPR) mediated by a high-density array of Al nanoparticles (NPs). The Al NPs with an average diameter of ∼40 nm were uniformly distributed near the AlGaN/AlGaN multiple quantum well active region for coupling 285 nm emission by block copolymer lithography. The internal quantum efficiency is enhanced by 57.

Spontaneously Formed CuS Catalysts for Selective and Stable Electrochemical Reduction of Industrial CO Gas to Formate.

The electrochemical CO reduction in aqueous media is a promising method for both the mitigation of climate changes and the generation of value-added fuels. Although many researchers have demonstrated selective and stable catalysts for electrochemical reduction of pure CO gas, the conversion of industrial CO gas has been limited. Here, we fabricated the copper sulfide catalysts (CuS), which were spontaneously formed by dipping a Cu foil into a laboratory-prepared industrial CO-purged 0.

Application of a high-throughput microcrystal delivery system to serial femtosecond crystallography.

Microcrystal delivery methods are pivotal in the use of serial femtosecond crystallography (SFX) to resolve the macromolecular structures of proteins. Here, the development of a novel technique and instruments for efficiently delivering microcrystals for SFX are presented. The new method, which relies on a one-dimensional fixed-target system that includes a microcrystal container, consumes an extremely low amount of sample compared with conventional two-dimensional fixed-target techniques at ambient temperature.

Subwavelength-scale nanorods implemented hexagonal pyramids structure as efficient light-extraction in Light-emitting diodes.

Subwavelength-scale nanorods were implemented on the hexagonal pyramid of photochemically etched light-emitting diodes (LEDs) to improve light extraction efficiency (LEE). Sequential processes of Ag deposition and inductively coupled plasma etching successfully produce nanorods on both locally unetched flat surface and sidewall of hexagonal pyramids. The subwavelength-scale structures on flat surface offer gradually changed refractive index, and the structures on side wall of hexagonal pyramid reduce backward reflection, thereby enhancing further enhancement of the light extraction efficiency.

Air-gap-embedded robust hazy films to reduce the screen-door effect in virtual reality displays.

We report a way to make an air-gap-embedded flexible film to reduce the screen-door effect (SDE) in virtual reality (VR) displays. Oxygen plasma was treated with a polyethylene terephthalate substrate to produce wavelength-scale micropatterns. These micropatterns induce an effective haze, but it is easily destroyed by a very small external scratch.

Ultrafast and Chemically Stable Transfer of Au Nanomembrane Using a Water-Soluble NaCl Sacrificial Layer for Flexible Solar Cells.

Large-scale industrial application of flexible device has called for development of transfer methods that deliver high yield and stability. Here, we show an ultrafast and chemically stable transfer method by using a water-soluble NaCl sacrificial layer. Extremely thin (10 nm) and large-area (4 in.

Nylon mesh-based sample holder for fixed-target serial femtosecond crystallography.

Fixed-target serial femtosecond crystallography (FT-SFX) was an important advance in crystallography by dramatically reducing sample consumption, while maintaining the benefits of SFX for obtaining crystal structures at room temperature without radiation damage. Despite a number of advantages, preparation of a sample holder for the sample delivery in FT-SFX with the use of many crystals in a single mount at ambient temperature is challenging as it can be complicated and costly, and thus, development of an efficient sample holder is essential. In this study, we introduced a nylon mesh-based sample holder enclosed by a polyimide film.

Nano-imprinting of refractive-index-matched indium tin oxide sol-gel in light-emitting diodes for eliminating total internal reflection.

Refractive-index (RI)-matched nanostructures are implemented in GaN-based light-emitting diodes (LEDs) for enhancing light output efficiency. The RI-matched indium tin oxide (ITO) nanostructures are successfully implemented in GaN-based lateral LEDs by using ITO sol-gel and nanoimprint lithography. The ITO sol-gel nanostructures annealed at 300 °C have RI of 1.

Flexible top-emitting organic light emitting diodes with a functional dielectric reflector on a metal foil substrate.

For flexible organic light emitting diodes (OLEDs), roll-to-roll production enables low-cost fabrication and wide-ranging applications. Choosing an appropriate substrate material is one of the critical issues in the fabrication of flexible OLEDs. We demonstrated top-emitting OLEDs with a highly reflective distributed Bragg reflector (DBR) using a metal foil substrate.

A strain induced subwavelength-structure for a haze-free and highly transparent flexible plastic substrate.

This paper presents a method to produce subwavelength-scale (<250 nm) AgCl nanostructures on a flexible plastic film, which is indispensable for highly efficient flexible displays. Using Cl2 plasma treatment on an Ag-coated plastic film, AgCl nanostructures were produced through the reaction of Ag atoms with Cl radicals. During the reaction, the volume of AgCl expands, leading to drastically changed surface morphology from a two-dimensional (2D) flat Ag surface to a 3D subwavelength-scale AgCl nanostructure.

Extremely flat metal films implemented by surface roughness transfer for flexible electronics.

We present an innovative approach to fabricate an extremely flat (EF) metal film which was done by depositing metal on an extremely flat mother substrate, then detaching the metal from the substrate. The detached flexible metal films had a roughness that was within 2% of the roughness of the mother substrate, so EFs with < 1 nm could be fabricated using the surface roughness transfer method. With quantitative analysis using synchrotron XPS, it was concluded that the chemical reaction of oxygen atoms with the metal film played a critical role in designing a peel-off system to get extremely flat metal films from the mother substrate.

Monolithic Nanoporous In-Sn Alloy for Electrochemical Reduction of Carbon Dioxide.

Nanostructured metal catalysts to convert CO to formate, which have been extensively studied over decades, have many problems such as durability, lifetime, high process temperature, and difficulty in controlling the morphology of nanostructures. Here, we report a facile method to fabricate monolithic nanoporous In-Sn alloy, a network of nanopores, induced by electroreduction of indium tin oxide nanobranches (ITO BRs). The electroreduction process concentrated a local electric field at the tip of the nanostructure, leading to current-assisted joule-heating to form a nanoporous In-Sn alloy.