Self-defect-passivation by Br-enrichment in FA-doped Cs 1?x FA x PbBr 3 quantum dots: towards high-performance quantum dot light-emitting diodes

摘要

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 Cs1?xFAxPbBr3 QDs. Due to the defect passivation by the enriched Br, the trap density in Cs1?xFAxPbBr3 significantly decreased after FA doping, and which improved the optical properties of Cs1?xFAxPbBr3 QDs and their QD-LEDs. PLQY of Cs1–xFAxPbBr3 QDs increased from 76.8% (x?=?0) to 85.1% (x?=?0.04), and Lmax and CEmax of Cs1–xFAxPbBr3 QD-LEDs were improved from Lmax?=?2880?cd?m?2 and CEmax?=?1.98?cd?A?1 (x?=?0) to Lmax?=?5200?cd?m?2 and CEmax?=?3.87?cd?A?1 (x?=?0.04). Cs1–xFAxPbBr3 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 Cs1–xFAxPbBr3 QD-LEDs deduced by UPS analyses.