Chanho Park

Structural colors (SCs) of photonic crystals (PCs) arise from selective constructive interference of incident light. Here, an ink-jet printable and rewritable block copolymer (BCP) SC display is demonstrated, which can be quickly written and erased over 50 times with resolution nearly equivalent to that obtained with a commercial office ink-jet printer. Moreover, the writing process employs an easily modified printer for position- and concentration-controlled deposition of a single, colorless, w

In addition to the demand for stimuli-responsive sensors that can detect various vital signals in epidermal skin, the development of electronic skin displays that quantitatively detect and visualize various epidermal stimuli such as the temperature, sweat gland activity, and conductance simultaneously are of significant interest for emerging human-interactive electronics used in health monitoring. Herein, a novel interactive skin display with epidermal stimuli electrode (ISDEE) allowing for the

The encapsulation of lead halide perovskite nanocrystals (PNCs) with an inert protective layer against moisture and the environment is a promising approach to overcome hinderances for their practical use in optoelectronic and biomedical applications. Herein, a facile method for synthesizing highly luminescent and biocompatible CsPbBr₃@SiO₂ core-shell PNCs with a controlled SiO₂ thickness, which are suitable for both cell imaging and drug delivery, is reported. Th

Soft ferroelectrics based on organic and organic-inorganic hybrid materials have gained much interest among researchers owing to their electrically programmable and remnant polarization. This allows for the development of numerous flexible, foldable, and stretchable nonvolatile memories, when combined with various crystal engineering approaches to optimize their performance. Soft ferroelectrics have been recently considered to have an important role in the emerging human-connected electronics th

Abstract Structural color (SC) arising from a periodically ordered self‐assembled block copolymer (BCP) photonic crystal (PC) is useful for reflective‐mode sensing displays owing to its capability of stimuli‐responsive structure alteration. However, a set of PC inks, each providing a precisely addressable SC in the full visible range, has rarely been demonstrated. Here, a strategy for developing BCP PC inks with tunable structures is presented. This involves solution‐blending of two lamellar‐for

Abstract Although carbon quantum dots (CQDs) are of great interest because of cost effectiveness and environmental compatibility with the facile tunability of their optical properties, poor photo‐ and electroluminescence (EL) of CQDs limits further implementation. Here, a novel bottom‐up synthetic route for fabricating highly crystalline CQDs suitable for high‐brightness blue light‐emitting diodes is demonstrated. The two‐step solution process is based on time‐controlled thermal carbonization of

Abstract Self‐healing electronic materials can substantially enhance the lifetime of a device as they can self‐repair mechanical damages, thereby recovering their initial electronic performance similar to human skin. Despite the development of various self‐healing electronic components such as electrodes and semiconducting carrier transport layers, self‐healing electroluminescence (EL) layers suitable for deformable displays, which require both high stretchability and self‐recovery function, hav

A new 60 V rating split gate trench MOSFET fabricated with the state-of-the-art process technology has been investigated and evaluated in the secondary synchronous rectifier board. It shows the best-in-class specific resistance of 10.9 mΩ·mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and the figure-of-merit (FOM) of 85 mΩ·nC which is the product of the on-resistance and the gate charge.

A triboelectric nanogenerator (TENG) is of tremendous interest owing to its high energy efficiency with a simple device architecture and applicability to various materials. Most previous topological surface modifications introduced for further improving the performance of a TENG are detrimental because they require expensive and/or harsh (e.g., high temperature and acidity) postetching processes, which limit the material choice and design of its components. Herein, we demonstrate an one-step rou

This study demonstrates transparent and flexible capacitive pressure sensors using a high-<i>k</i> ionic gel composed of an insulating polymer (poly(vinylidene fluoride-<i>co</i>-trifluoroethylene-<i>co</i>-chlorofluoroethylene), P(VDF-TrFE-CFE)) blended with an ionic liquid (IL; 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) amide, [EMI][TFSA]). The thermal melt recrystallization of the P(VDF-TrFE-CFE):[EMI][TFSA] blend films develops the characteristic topological semicrystalline sur

Epitaxial crystallization of thin poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) films is important for the full utilization of their ferroelectric properties. Epitaxy can offer a route for maximizing the degree of crystallinity with the effective orientation of the crystals with respect to the electric field. Despite various approaches for the epitaxial control of the crystalline structure of PVDF-TrFE, its epitaxy on a semiconductor is yet to be accomplished. Herein, the epitaxial

Gene expression profile is numerical data of gene expression levels from organism, measured on the microarray. In general, each specific tissue indicates different expression level in related genes, so that it is possible to classify disease by gene expression profile. For classification, it is needed to select related genes called feature selection, because all the genes are not useful for classification. We propose GA-based method for searching optimal ensemble of feature-classifier pairs of g

Abstract The development of anodes for lithium‐ion batteries (LIBs) based on liquid‐phase‐exfoliated 2D transition metal dichalcogenide (TMD) nanosheets has been studied extensively because their intrinsic capacity is higher than graphite. Since most semiconducting TMDs possess low electrical conductivity and lithium‐ion diffusivity, expensive processes are necessary such as the addition of conductive fillers, chemically converted metallic phase transformation, and topological nano‐fabrication.

Abstract The development of a sub‐50 nm nanopattern of a thin perovskite film is of significant interest with its excellent photo‐electronic properties and environmental stability. By employing nanoimprinting of a moldable perovskite precursor, self‐assembled with a block copolymer, a thin perovskite nanopattern with excellent photo‐electronic stability is developed over a large area. Approximately 40 nm nanodomains consisting of perovskite crystals, which are 10 nm in diameter, are templated in