High-Performance Green Light-Emitting Diodes Based on MAPbBr₃ with π-Conjugated Ligand

Abstract

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 (MAPbBr3)-based PeLEDs by reducing the MAPbBr3 crystal size to the nanoscale and reducing the trap density. Moreover, the properties of PeLEDs with ABN were further improved using a surface-modified hole-transport layer (HTL) with a hydrophilic polymer. Finally, a bright green PeLED was fabricated, which exhibited the maximum luminance of 3350 cd/m2 with an external quantum efficiency of 8.85%. Therefore, it is believed that the use of proper ligands for the perovskite layer and the optimization of the charge-transport layer have great potential for the development of high-performance PeLEDs.

High‐Performance Perovskite‐Based Blue Light‐Emitting Diodes with Operational Stability by Using Organic Ammonium Cations as Passivating Agents

“…[ 32 ] Second, the poor morphology of the perovskite film leads to the poor performance of the PeLED. [ 33,34 ] The SEM images in Figure S8 in the Supporting Information show the morphology of the perovskite films with different passivating agents deposited on the TFB/PEDOT:PSS/ITO/glass substrates. As shown in Figure S8a in the Supporting Information, the pristine perovskite film has poor morphology with large‐sized pinholes.…”

Enabling Quasi‐2D Perovskite‐Compatible Growth Environment for Efficient Light‐Emitting Diodes

“…Notably, an obvious shoulder peak around 12.5° (indicated with a star) is found in the case of VAG@200 that possibly corresponds to unreacted PbBr 2 . [ 61 ] Potentially, DMSO vapors would coordinate with PbBr 2 during the film formation under VAG and the residual DMSO would gradually evaporate from the film upon thermal annealing. However, owing to the highly concentrated DMSO environment for VAG@200, high density of DMSO‐PbBr 2 species would be formed and it is possible that all of such intermediates may not crystallize into perovskite domains because of the quick evaporation of the DMSO under thermal treatment, thereby leaving a small portion of unreacted PbBr 2 .…”

Advances on perovskite quantum dot electroluminescent devices

“…[26] . (a) Evolution of EL spectra of green QD-LED made from PVK with increasing voltage; (b) current density (J) and luminance (L) versus driving voltage (V); (c) current efficiency (η A ) and external quantum efficiency (η EQE ) versus luminance 子点薄膜的电荷传导能力, 增强量子点薄膜的电荷注 入 [65] , 例如配体密度、长度控制、配体交换以及选择 导电有机官能团 [66,67] . 此外, 可以进一步通过其他钝化过程, 降低配体动 态吸附脱附、快速结晶引起的缺陷, 提高量子点薄膜 的辐射效率.…”

“…位于量子点表面的卤素空位 [61,69] 引起的表 面缺陷对电致发光的影响很大, 特别是由于量子点比 表面积高, 卤素空位引起的表面缺陷影响就更大. 因 此, 对表面缺陷的钝化十分重要, 可以进一步通过表面 涂层、有机/无机(卤素)盐 [53,62,63,65,70,71] 、阴离子交换策 略 , 蓝光器件的外量子效 率也突破了12% [52] . 除了进一步提高器件的效率以外, 激子辐射机制、器件稳定性、环境友好型量子点器件 等方面需要更多的关注和进一步的研究.…”