Enhancing Efficiency and Stability of Tin Halide Perovskite Light-Emitting Diodes via Engineered Alkali/Multivalent Metal Salts.

Sn-based perovskite light-emitting diodes (PeLEDs) have emerged as promising alternatives to Pb-based PeLEDs with their rapid increase in performance owing to the various research studies on inhibiting Sn oxidation. However, the absence of defect passivation strategies for Sn-based perovskite LEDs necessitates further research in this field. We performed systematic studies to investigate the design rules for defect passivation agents for Sn-based perovskites by incorporating alkali/multivalent metal salts with various cations and anions.

Three-Dimensional Touch Device with Two Terminals.

A crossbar array is an essential element that determines the operating position and simplifies the structure of devices. However, in the crossbar array, wiring numerous electrodes to address many positions poses significant challenges. In this study, a method is proposed that utilizes only two electrodes to determine multiple positions.

Ultrathin Metal Film on Graphene for Percolation-Threshold-Limited Thermal Emissivity Control.

Translucent Au/graphene hybrid films are shown to be effective in reducing thermal emission from the underlying surfaces when the deposition thickness of Au is close to the percolation threshold. The critical Au deposition thickness for an abrupt change in emissivity is reduced from 15 nm (Si substrate) to a percolation-threshold-limited thickness of 8.5 nm (graphene/Si substrate) because of the chemical inertness of graphene leading to the deposited Au atoms forming a thin, crystalline layer.

Super-Bright Green Perovskite Light-Emitting Diodes Using Ionic Liquid Additives.

Halide perovskites have potential for use in next-generation low-cost, high-efficiency, and highly color-pure light-emitting diodes (LED) that can be used in various applications, such as flat and flexible displays and solid-state lighting. However, they still lag behind other mature technologies, such as organic LEDs and inorganic LEDs, in terms of performance, particularly brightness. This lag is partly due to the insulating nature of the long-chain organic ligands used to control the perovskite-film morphology.

Sensing with MXenes: Progress and Prospects.

Various fields of study consider MXene a revolutionary 2D material. Particularly in the field of sensors, the metal-like high electrical conductivity and large surface area of MXenes are desirable characteristics as an alternative sensor material that can transcend the boundaries of existing sensor technology. This critical review provides a comprehensive overview of recent advances in MXene-based sensor technology and a roadmap for commercializing MXene-based sensors.

Electroplated Silver-Nickel Core-Shell Nanowire Network Electrodes for Highly Efficient Perovskite Nanoparticle Light-Emitting Diodes.

The low sheet resistance and high optical transparency of silver nanowires (AgNWs) make them a promising candidate for use as the flexible transparent electrode of light-emitting diodes (LEDs). In a perovskite LED (PeLED), however, the AgNW electrode can react with the overlying perovskite material by redox reactions, which limit the electroluminescence efficiency of the PeLED by causing the degradation of and generating defect states in the perovskite material. In this study, we prepared Ag-Ni core-shell NW electrodes using the solution-electroplating technique to realize highly efficient PeLEDs based on colloidal formamidinium lead bromide (FAPbBr) nanoparticles (NPs).

Wearable and Semitransparent Pressure-Sensitive Light-Emitting Sensor Based on Electrochemiluminescence.

Tactile sensors are being researched as a key technology for developing an electronic skin and a wearable display, which have recently been attracting much attention. However, to develop a next-generation wearable tactile sensor, it is necessary to implement an interactive display that responds immediately to external stimuli. Herein, a wearable and semitransparent pressure-sensitive light-emitting sensor (PLS) based on electrochemiluminescence (ECL) is successfully implemented with visual alarm functions to prevent damage to the human body from external stimuli.

Minimizing Residual Images of Amorphous Indium Gallium Zinc Oxide Thin-Film Transistor-Based Flexible Organic Light-Emitting Diode Displays by Controlling Oxygen Partial Pressure.

Plastic organic light emitting diode displays suffer from residual image, which is closely connected with the hysteresis of the driving thin-film transistor in the pixels. Therefore, in researching paper, we manufactured an OLED display comprise a polyimide substrate and an amorphous indium gallium zinc oxide thin film transistor active layer. Paper proposed a solution for reducing hysteresis through oxygen partial pressure control and evaluated it using hysteresis analysis.

Residual Image Reduction Using Electric Field Shield Metal in Plastic Organic Light-Emitting Diode Display.

A plastic organic light-emitting diode display is a device that emits light in an organic layer in proportion to the amount of current applied from a thin film transistor, which constitutes a pixel. However, it was confirmed that the residual image was shown by the operation of the thin film transistor. To suppress residual image, the effect of electric field was studied in operation of a-IGZO thin film transistor.

Residual Image Suppression Through Annealing Process of Amorphous Indium Gallium Zinc Oxide Thin Film Transistor for Plastic Organic Light-Emitting Diode Display.

For the evaluation of the residual image suppression, the amorphous indium-gallium-zinc-oxide thin film transistor was manufactured with electric field shield metal on silicon oxide multi-buffer layer, without the need for a silicon crystallization process through the excimer laser process, and is advantageous for the manufacture of large-scale plastic organic light-emitting display. We conducted a study on the propensity to suppress a residual image according to the temperature of the annealing process in amorphous indium gallium zinc oxide. The evaluation divided by the ambient process temperature conditions to measure the change and restoration tendency of the gray current by the black/white current of thin film transistors, and for precise measurement of the current change intervals, the current was analyzed in 0.

High-Performance Green Light-Emitting Diodes Based on MAPbBr with π-Conjugated Ligand.

The morphology, crystal size, and trap density of perovskite films significantly affect the luminescent properties of perovskite light-emitting diodes (PeLEDs). Recently, numerous studies have been conducted on ligands that surround the surface of perovskite crystals and passivate the trap sites to improve the performance of PeLEDs. In this study, a 4-aminobenzonitrile (ABN) ligand improved the performance of methylammonium lead bromide (MAPbBr)-based PeLEDs by reducing the MAPbBr crystal size to the nanoscale and reducing the trap density.

Violet Light-Emitting Diodes Based on p-CuI Thin Film/n-MgZnO Quantum Dot Heterojunction.

As the lighting technology evolves, the need for violet light-emitting diodes (LEDs) is growing for high color rendering index lighting. The present technology for violet LEDs is based on the high-cost GaN materials and metal-organic chemical vapor deposition process; therefore, there have recently been intensive studies on developing low-cost alternative materials and processes. In this study, for the first time, we demonstrated violet LEDs based on low-cost materials and processes using a p-CuI thin film/n-MgZnO quantum dot (QD) heterojunction.

Paper-like flexible optically isotropic liquid crystal film for tunable diffractive devices.

We have demonstrated a paper-like diffractive film in which nano-structured liquid crystal droplets are embedded in elastomeric monomer incorporated polymer matrix by polymerization induced phase-separation. The film with voltage-tunable phase grating exhibits an optically isotropic phase with high transparency and an effective chromatic diffraction for an incident white light with sub-millisecond switching time. In addition, the proposed diffractive film is exhibiting excellent chemical stability against organic and inorganic solvents.

Fast switching, high contrast and high resolution liquid crystal device for virtual reality display.

Virtual reality-head mounted displays require a display with high resolution over 2000 ppi, super-fast response time and high contrast ratio for realizing super image quality at near-eyes. Several liquid crystal devices utilizing fringe-field switching (FFS) mode, having response times less than of half of conventional FFS mode, were proposed for this purpose. However, its contrast ratio is still less than 2000:1 because of intrinsic electro-optic characteristics of homogenous alignment mode and also realizing high resolution like 2000 ppi has some difficulty because twist deformation of liquid crystals can easily affect liquid crystal orientation near pixels.

Flexible multi-wavelength photodetector based on porous silicon nanowires.

Porous silicon nanowires (PSi NWs) responding to red, green and blue lights simultaneously are reported in this study. NWs with a diameter of 120 nm were prepared from p-type Si wafer by metal-catalyst-assisted etching. The NWs produced in this manner had an outer porous region consisting of Si nanocrystals small enough to ensure the quantum confinement effect.

High-Performance Flexible ZnO Nanorod UV/Gas Dual Sensors Using Ag Nanoparticle Templates.

Flexible zinc oxide (ZnO) nanorod (NR) ultraviolet (UV)/gas dual sensors using silver (Ag) nanoparticle (NP) templates were successfully fabricated on a polyimide substrate with nickel electrodes. Arrays of Ag NPs were used as a template for the growth of ZnO NRs, which could enhance the flexibility and the sensing properties of the devices through the localized surface plasmon resonance (LSPR) effect. The Ag NPs were fabricated by the rapid thermal annealing process of Ag thin films, and ZnO NRs were grown on Ag NPs to maximize the surface area and form networks with rod-to-rod contacts.

Effect of ribbon width on electrical transport properties of graphene nanoribbons.

There has been growing interest in developing nanoelectronic devices based on graphene because of its superior electrical properties. In particular, patterning graphene into a nanoribbon can open a bandgap that can be tuned by changing the ribbon width, imparting semiconducting properties. In this study, we report the effect of ribbon width on electrical transport properties of graphene nanoribbons (GNRs).

Effect of Nonionic Surfactant Additive in PEDOT:PSS on PFO Emission Layer in Organic-Inorganic Hybrid Light-Emitting Diode.

Poly(9,9-dioctylfluorene) (PFO) has attracted significant interests owing to its versatility in electronic devices. However, changes in its optical properties caused by its various phases and the formation of oxidation defects limit the application of PFO in light-emitting diodes (LEDs). We investigated the effects of the addition of Triton X-100 (hereinafter shortened as TX) in poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) to induce interlayer diffusion between PEDOT:PSS and PFO to enhance the stability of the PFO phase and suppress its oxidation.

Enhanced Light Stability of InGaZnO Thin-Film Transistors by Atomic-Layer-Deposited YO with Ozone.

We report the effect of YO passivation by atomic layer deposition (ALD) using various oxidants, such as HO, O plasma, and O, on In-Ga-Zn-O thin-film transistors (IGZO TFTs). A large negative shift in the threshold voltage (V) was observed in the case of the TFT subjected to the HO-ALD YO process; this shift was caused by a donor effect of negatively charged chemisorbed HO molecules. In addition, degradation of the IGZO TFT device performance after the O plasma-ALD YO process (field-effect mobility (μ) = 8.

High-Performance Green Light-Emitting Diodes Based on MAPbBr-Polymer Composite Films Prepared by Gas-Assisted Crystallization.

The morphology of perovskite films has a significant impact on luminous characteristics of perovskite light-emitting diodes (PeLEDs). To obtain a highly uniform methylammonium lead tribromide (MAPbBr) film, a gas-assisted crystallization method is introduced with a mixed solution of MAPbBr precursor and polymer matrix. The ultrafast evaporation of the solvent causes a high degree of supersaturation which expedites the generation of a large number of nuclei to form a MAPbBr-polymer composite film with full surface coverage and nano-sized grains.

Reaction Mechanism of Area-Selective Atomic Layer Deposition for AlO Nanopatterns.

The reaction mechanism of area-selective atomic layer deposition (AS-ALD) of AlO thin films using self-assembled monolayers (SAMs) was systematically investigated by theoretical and experimental studies. Trimethylaluminum (TMA) and HO were used as the precursor and oxidant, respectively, with octadecylphosphonic acid (ODPA) as an SAM to block AlO film formation. However, AlO layers began to form on the ODPA SAMs after several cycles, despite reports that CH-terminated SAMs cannot react with TMA.

Boosting up the electrical performance of low-grade PEDOT:PSS by optimizing non-ionic surfactants.

Although PEDOT:PSS has already been applied to various electronic devices, commercialized PEDOT:PSS products having high conductivity are expensive, which is a considerable burden on device manufacturing. In this study, we optimize non-ionic surfactants mixed in a PEDOT:PSS solution to upgrade a low-grade product of low conductivity to the level of a high-grade product of high conductivity. This study systematically investigates the phase diagram, morphology, conductivity, and mechanical stability of the PEDOT:PSS films according to the hydrophilicity of non-ionic surfactants.

Surface-Embedded Stretchable Electrodes by Direct Printing and their Uses to Fabricate Ultrathin Vibration Sensors and Circuits for 3D Structures.

Printing is one of the easy and quick ways to make a stretchable wearable electronics. Conventional printing methods deposit conductive materials "on" or "inside" a rubber substrate. The conductors made by such printing methods cannot be used as device electrodes because of the large surface topology, poor stretchability, or weak adhesion between the substrate and the conducting material.

Micropatternable Double-Faced ZnO Nanoflowers for Flexible Gas Sensor.

Micropatternable double-faced (DF) zinc oxide (ZnO) nanoflowers (NFs) for flexible gas sensors have been successfully fabricated on a polyimide (PI) substrate with single-walled carbon nanotubes (SWCNTs) as electrode. The fabricated sensor comprises ZnO nanoshells laid out on a PI substrate at regular intervals, on which ZnO nanorods (NRs) were grown in- and outside the shells to maximize the surface area and form a connected network. This three-dimensional network structure possesses multiple gas diffusion channels and the micropatterned island structure allows the stability of the flexible devices to be enhanced by dispersing the strain into the empty spaces of the substrate.