Kim Young-Hoon, Park Jinwoo, Kim Sungjin, Kim Joo Sung, Xu Hengxing, Jeong Su-Hun, Hu Bin, Lee Tae-Woo
Department of Materials Science and Engineering, Seoul National University, Seoul, Republic of Korea.
Department of Energy Engineering, Hanyang University, Seoul, Republic of Korea.
Nat Nanotechnol. 2022 Jun;17(6):590-597. doi: 10.1038/s41565-022-01113-4. Epub 2022 May 16.
Cost-effective, high-throughput industrial applications of metal halide perovskites in large-area displays are hampered by the fundamental difficulty of controlling the process of polycrystalline film formation from precursors, which results in the random growth of crystals, leading to non-uniform large grains and thus low electroluminescence efficiency in large-area perovskite light-emitting diodes (PeLEDs). Here we report that highly efficient large-area PeLEDs with high uniformity can be realized through the use of colloidal perovskite nanocrystals (PNCs), decoupling the crystallization of perovskites from film formation. PNCs were precrystallized and surrounded by organic ligands, and thus they were not affected by the film formation process, in which a simple modified bar-coating method facilitated the evaporation of residual solvent to provide uniform large-area films. PeLEDs incorporating the uniform bar-coated PNC films achieved an external quantum efficiency (EQE) of 23.26% for a pixel size of 4 mm and an EQE of 22.5% for a large pixel area of 102 mm with high reproducibility. This method provides a promising approach towards the development of large-scale industrial displays and solid-state lighting using perovskite emitters.
金属卤化物钙钛矿在大面积显示器中的高性价比、高通量工业应用受到从前驱体控制多晶膜形成过程这一基本难题的阻碍，这会导致晶体随机生长，进而产生不均匀的大晶粒，从而使大面积钙钛矿发光二极管（PeLED）的电致发光效率较低。在此，我们报告通过使用胶体钙钛矿纳米晶体（PNC）可实现具有高均匀性的高效大面积PeLED，将钙钛矿的结晶与成膜过程解耦。PNC预先结晶并被有机配体包围，因此它们不受成膜过程的影响，其中一种简单的改进刮涂法有助于残留溶剂的蒸发，以提供均匀的大面积薄膜。包含均匀刮涂PNC薄膜的PeLED在像素尺寸为4毫米时实现了23.26%的外量子效率（EQE），在102毫米的大像素面积下实现了22.5%的EQE，且具有高重现性。该方法为使用钙钛矿发光体开发大规模工业显示器和固态照明提供了一种有前景的途径。
