Organic-inorganic hybrid perovskites are emerging low-cost emitters with very high color purity, but their low luminescent efficiency is a critical drawback. We boosted the current efficiency (CE) of perovskite light-emitting diodes with a simple bilayer structure to 42.9 candela per ampere, similar to the CE of phosphorescent organic light-emitting diodes, with two modifications: We prevented the formation of metallic lead (Pb) atoms that cause strong exciton quenching through a small increase in methylammonium bromide (MABr) molar proportion, and we spatially confined the exciton in uniform MAPbBr3 nanograins (average diameter = 99.7 nanometers) formed by a nanocrystal pinning process and concomitant reduction of exciton diffusion length to 67 nanometers. These changes caused substantial increases in steady-state photoluminescence intensity and efficiency of MAPbBr3 nanograin layers.

Bright organic/inorganic hybrid perov-skite light-emitting diodes (PrLEDs) are realized by using CH3 NH3 PbBr3 as an emitting layer and self-organized buffer hole-injection layer (Buf-HIL). The PrLEDs show high luminance, current efficiency, and EQE of 417 cd m(-2) , 0.577 cd A(-1) , and 0.125%, respectively. Buf-HIL can facilitate hole injection into CH3 NH3 PbBr3 as well as block exciton quenching.

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Over the past few years the performance of colloidal quantum dot-light-emitting diode (QLED) has been progressively improved. However, most of QLED work has been fulfilled in the form of monochromatic device, while full-color-enabling white QLED still remains nearly unexplored. Using red, green, and blue quantum dots (QDs), herein, we fabricate bichromatic and trichromatic QLEDs through sequential solution-processed deposition of poly(9-vinlycarbazole) (PVK) hole transport layer, two or three types of QDs-mixed multilayer, and ZnO nanoparticle electron transport layer. The relative electroluminescent (EL) spectral ratios of constituent QDs in the above multicolored devices are found to inevitably vary with applied bias, leading to the common observation of an increasing contribution of a higher-band gap QD EL over low-band gap one at a higher voltage. The white EL from a trichromatic device is resolved into its primary colors through combining with color filters, producing an exceptional color gamut of 126% relative to National Television Systems Committee (NTSC) color space that a state-of-the-art full-color organic LED counterpart cannot attain. Our trichromatic white QLED also displays the record-high EL performance such as the peak values of 23,352 cd/m(2) in luminance, 21.8 cd/A in current efficiency, and 10.9% in external quantum efficiency.

Polymer residue-free graphene nanoribbons (GNRs) of 200 nm width at 1 μm pitch were periodically generated in an area of 1 cm(2) via laser interference lithography using a chromium interlayer prior to photoresist coating. High-quality GNRs were evidenced by atomic force microscopy, micro-Raman spectroscopy, and X-ray photoelectron spectroscopy measurements. Palladium nanoparticles were then deposited on the GNRs as catalysts for sensing hydrogen gases, and the GNR array was utilized as an electrically conductive path with less electrical noise. The palladium-decorated GNR array exhibited a rectangular sensing curve with unprecedented rapid response and recovery properties: 90% response within 60 s at 1000 ppm and 80% recovery within 90 s in nitrogen ambient. In addition, reliable and repeatable sensing behaviors were revealed when the array was exposed to various gas concentrations even at 30 ppm.