Self-defect-passivation by Br-enrichment in FA-doped Cs1−xFAxPbBr3 quantum dots: towards high-performance quantum dot light-emitting diodes
Young Ran Park, Sangwon Eom, Hong Hee Kim, Won Kook Choi, Youngjong Kang
Abstract
Abstract Halide vacancy defect is one of the major origins of non-radiative recombination in the lead halide perovskite light emitting devices (LEDs). Hence the defect passivation is highly demanded for the high-performance perovskite LEDs. Here, we demonstrated that FA doping led to the enrichment of Br in Cs 1− x FA x PbBr 3 QDs. Due to the defect passivation by the enriched Br, the trap density in Cs 1− x FA x PbBr 3 significantly decreased after FA doping, and which improved the optical properties of Cs 1− x FA x PbBr 3 QDs and their QD-LEDs. PLQY of Cs 1– x FA x PbBr 3 QDs increased from 76.8% ( x = 0) to 85.1% ( x = 0.04), and L max and CE max of Cs 1– x FA x PbBr 3 QD-LEDs were improved from L max = 2880 cd m −2 and CE max = 1.98 cd A −1 ( x = 0) to L max = 5200 cd m −2 and CE max = 3.87 cd A −1 ( x = 0.04). Cs 1– x FA x PbBr 3 QD-LED device structure was optimized by using PVK as a HTL and ZnO modified with b-PEI as an ETL. The energy band diagram of Cs 1– x FA x PbBr 3 QD-LEDs deduced by UPS analyses.