Sequential layer-by-layer deposition for high-performance fully thermal-evaporated red perovskite light-emitting diodes
Yajing Li, Na Meng, Yutian Xu, Bufan Yu, Junhao Liu, Yuanhao Cui, Ziqiang Wang, Xiaoqin Ke, Tengfei Pan, Min Xue, Jiangshan Chen, Dongge Ma, Lingfeng Chao, Zhelu Hu, Yingdong Xia, Qingxun Guo, Yonghua Chen, Wei Huang
Abstract
Thermal-evaporated perovskite light-emitting diodes are highly promising for future display and lighting. However, multi-source co-evaporation faces challenges such as difficulty in regulating crystallinity, especially for red perovskite light-emitting diodes, whose external quantum efficiencies are still less than 2%. Here, we demonstrate a facile layer-by-layer thermal-evaporation strategy to fabricate high-quality perovskite-emitting films with tunable emission wavelengths. 5-Aminovaleric acid is introduced to regulate interfacial reactions during deposition, slow down crystallization during post-annealing, and passivate defects through coordination interactions. This approach yields perovskite emitting layers with high uniformity and luminance efficiency. As a result, red (670 nm) and deep-red (730 nm) perovskite light-emitting diodes achieve maximum external quantum efficiencies of 9% and 7.27%, and luminance of over 1500 cd m-2 and 200 W s-1 m-2, respectively. Furthermore, large-area (2500 mm²) and patterned perovskite thin films and light-emitting diodes with outstanding uniformity are successfully demonstrated. Li et al. report layer-by-layer fully thermal evaporated perovskite LEDs using 5-aminovaleric acid as an additive to regulate the crystallisation. Red LEDs with efficiency of 9% and 7.27% are achieved at 670 nm and 730 nm, respectively. The technique is extendable to deposit large-area and patterned perovskite thin films.