High-Performance Perovskite Light-Emitting Diode with Enhanced Operational Stability Using Lithium Halide Passivation
Tian Wu‡1, Junnan Li‡1, Yatao Zou‡1,2, Hao Xu1, Kaichuan Wen3, Shanshan Wan1, Sai Bai*2, Tao Song*1, John A. McLeod*1, Steffen Duhm1, Feng Gao2, Baoquan Sun*1
1Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, 199 Ren’ai Road, Suzhou 215123, People’s Republic of China
2Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping, SE-58183, Sweden.
3Key Laboratory of Flexible Electronics (KLOFE) and Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University (Nanjing Tech), Nanjing, China
Defect passivation has been demonstrated to be effective in improving the radiative recombination of charge carriers in perovskites, and consequently device performance of the resultant perovskite light-emitting diodes (LEDs). State-of-the-art useful passivation agents in perovskite LEDs are mostly organic chelating molecules, which, however, simultaneously sacrifice the charge transport properties and thermal stability of the resultant perovskite emissive layers, deteriorating the performance especially the operational stability of the devices. In this work, we demonstrate that lithium halides can efficiently passivate defects of halide vacancies and reduce trap state density, suppressing ion migration in perovskite films. Efficient green perovskite LEDs based on all inorganic CsPbBr3 perovskite with a peak external quantum efficiency of 16.2% as well as a high maximum brightness of 50278 cd m-2 are achieved. In addtion, the device shows decent stability even under a brightness of 104 cd m-2. We highlight the universal applicability of defect passivation using lithium halides, which enable us to improve the efficiency and stability of blue and red perovskite LEDs.