0000000000484535
AUTHOR
Vittal Prakasam
Large area perovskite light-emitting diodes by gas-assisted crystallization:
Halide perovskites have been gaining considerable attention recently for use in light-emitting applications, due to their bandgap tunability, color purity and low cost fabrication methods. However, current fabrication techniques limit the processing to small-area devices. Here, we show that a facile N 2 gas-quenching technique can be used to make methylammonium lead bromide-based perovskite light-emitting diodes (PeLEDs) with a peak luminance of 6600 cd m −2 and a current efficiency of 7.0 cd A −1 . We use this strategy to upscale PeLEDs to large-area substrates (230 cm 2 ) by developing a protocol for slot-die coating combined with gas-quenching. The resulting large area devices (9 device…
Metal Halide Perovskites for Light-Emitting Applications
Los dispositivos electrónicos modernos tales como televisores inteligentes, ordenadores portátiles, tabletas y teléfonos móviles requieren del uso de pantallas planas. Esto se logró en la última década usando pantallas de cristal líquido. Sin embargo, las proyecciones futuras llevan a usar pantallas flexibles y ligeras, un desafío importante para la tecnología convencional. Esto ha impulsado el desarrollo de materiales electroluminiscentes que son eficientes y tienen un contraste excelente. Como resultado de ello, nacieron los diodos orgánicos de emisión de luz (OLEDs), que han conseguido instalarse en el mercado. Sin embargo, esta tecnología es aún cara debido a la baja rentabilidad del pr…
Efficient Perovskite Light-Emitting Diodes: Effect of Composition, Morphology, and Transport Layers
Organic-inorganic metal halide perovskites are emerging as novel materials for light-emitting applications due to their high color purity, band gap tunability, straightforward synthesis, and inexpensive precursors. In this work, we improve the performance of three-dimensional perovskite light-emitting diodes (PeLEDs) by tuning the emissive layer composition and thickness and by using small-molecule transport layers. Additionally, we correlate PeLED efficiencies to the perovskite structure and morphology. The results show that the PeLEDs containing perovskites with an excess of methylammonium bromide (MABr) to lead bromide (PbBr2) in a 2:1 ratio and a layer thickness of 80 nm have the highes…
Degradation mechanisms in organic lead halide perovskite light-emitting diodes
Organic–inorganic metal halide perovskites have attracted significant attention for low-cost, high-efficiency, color-pure light-emitting applications. However, as seen in many reports so-far, perovskite light-emitting diodes (PeLED) suffer from poor operational lifetime, limiting their practical use. The underlying degradation mechanism is a topic of crucial importance. Here, the degradation mechanisms of methylammonium lead bromide based PeLED are investigated. When the PeLED is electrically biased, there is an initial raise in the luminance followed by a rapid reduction in luminance and current density. Microscopic studies reveal the formation of micrometer-sized spots that are photolumin…