Order-Order Transition in Statistical Copolymer Thin Film Induced by LCST-Type Behavior.

In this paper, we describe the formation of an ordered structure in a copolymer thin film through hydration, which subsequently transitions to a different ordered structure upon dehydration. A statistical copolymer of poly(-octadecyl acrylamide--hydroxymethyl acrylamide) with a comonomer content ratio of 1:1, denoted as p(ODA50/HEAm50), was synthesized via free radical copolymerization. We prepared a thin film of this copolymer on a solid substrate and annealed it at 60 °C under humid conditions.

Janus metallic film with gold and silver luster by electroless deposition of silver using poly(dopamine acrylamide) thin film.

Films that exhibit different metallic luster on the front and back, called Janus metallic films, have broad applications ranging from design materials to optical devices. However, the fabrication of these films is often a complicated process involving multiple metal deposition steps, thermal annealing, and calcination. Herein, we report the simple preparation of a Janus metallic film by electroless deposition of silver on a poly(dopamine acrylamide) (pDOPAm) thin film.

Energy Transfer between Size-Controlled CsPbI Quantum Dots for Light-Emitting Diode Application.

Perovskite quantum dots (PQDs) are applicable in light-emitting diodes (LEDs) owing to their color tunability, high color purity, and excellent photoluminescence quantum yield (PLQY) in the solution state. However, a PQD film obtained through nonradiative recombination by concentration quenching and the formation of surface defects exhibited a low PLQY. In this study, we focused on the energy transfer between PQDs with different energy gaps () to reduce nonradiative recombination in the film state and consequently achieve high device performance.

Gel permeation chromatography process for highly oriented CsCuI nanocrystal film.

The emergence of green materials has attracted considerable attention in the field of optoelectronics. Copper-based lead-free metal halide (with a near-unity quantum yield) obtained from CsCuI nanocrystals (NCs) can exhibit blue emission with a wavelength of 440 nm and provide outstanding stability for various applications. However, in practical applications, colloidal dispersion purity and film quality are inadequate toward a high-performance device.

Two-Step Crystallization for Low-Oxidation Tin-Based Perovskite Light-Emitting Diodes.

Metal halide perovskites attract significant attention because of their excellent optoelectronic and semiconducting properties. However, there are environmental concerns related to the toxicity of the lead metal that is mainly used in these perovskites. PEASnI perovskite is a potential candidate for lead-free perovskites because of its pure red emission.

All-Inorganic Quantum-Dot LEDs Based on a Phase-Stabilized α-CsPbI Perovskite.

The all-inorganic nature of CsPbI perovskites allows to enhance stability in perovskite devices. Research efforts have led to improved stability of the black phase in CsPbI films; however, these strategies-including strain and doping-are based on organic-ligand-capped perovskites, which prevent perovskites from forming the close-packed quantum dot (QD) solids necessary to achieve high charge and thermal transport. We developed an inorganic ligand exchange that leads to CsPbI QD films with superior phase stability and increased thermal transport.

Neodymium Chloride-Doped Perovskite Nanocrystals for Efficient Blue Light-Emitting Devices.

Metal halides doping of perovskite nanocrystals (NCs) has been shown to precisely control nonradiative pathways and to improve photoluminescence quantum yield (PLQY). Here, we report a trivalent lanthanide halide neodymium (III) chloride (NdCl)-doped perovskite NCs prepared with a post-synthetic room temperature treatment for efficient blue light-emitting devices (LEDs). The Nd 3d and Cl 2p core peaks were observed in the NdCl-doped NCs, which allowed for simultaneous doping of Nd and Cl into the pristine CsPbBr NCs.

Surface Crystal Growth of Perovskite Nanocrystals via Postsynthetic Lead(II) Bromide Treatment to Increase the Colloidal Stability and Efficiency of Light-Emitting Devices.

The surface modification of metal halide perovskite nanocrystals (NCs) significantly impacts their optical properties and colloidal stability. This subsequently affects the performance of light-emitting devices (LEDs). Therefore, numerous surface passivation techniques like ligand exchange and metal halide doping have been explored to passivate the surface defects of perovskite NCs and obtain highly efficient LEDs.

Chelating-agent-assisted control of CsPbBr quantum well growth enables stable blue perovskite emitters.

Metal halide perovskites have emerged as promising candidates for solution-processed blue light-emitting diodes (LEDs). However, halide phase segregation - and the resultant spectral shift - at LED operating voltages hinders their application. Here we report true-blue LEDs employing quasi-two-dimensional cesium lead bromide with a narrow size distribution of quantum wells, achieved through the incorporation of a chelating additive.

Bipolar-shell resurfacing for blue LEDs based on strongly confined perovskite quantum dots.

Colloidal quantum dot (QD) solids are emerging semiconductors that have been actively explored in fundamental studies of charge transport and for applications in optoelectronics. Forming high-quality QD solids-necessary for device fabrication-requires substitution of the long organic ligands used for synthesis with short ligands that provide increased QD coupling and improved charge transport. However, in perovskite QDs, the polar solvents used to carry out the ligand exchange decompose the highly ionic perovskites.

Purification of Perovskite Quantum Dots Using Low-Dielectric-Constant Washing Solvent "Diglyme" for Highly Efficient Light-Emitting Devices.

Cesium lead halide (CsPbX, X = Cl, Br, or I) perovskite quantum dots (QDs) are known as ionic nanocrystals, and their optical properties are greatly affected by the washing solvent used during the purification process. Here, we demonstrate the purification process of CsPbBr perovskite QDs using low-dielectric-constant solvents to completely remove impurities, such as the reaction solvent and desorbed ligands. The use of the ether solvent diethylene glycol dimethyl ether (diglyme), having a low dielectric constant of ε = 7.