Influence of high concentration of Bi dopant on the structural and optical properties of CsPbBr3 perovskite nanocrystals

Currently, all-inorganic cesium lead halide perovskite nanocrystals (NCs) have shown great potential for high-performance light-emitting diodes (LEDs), solar cells, and photodetectors. Doping of metal ions is one of the most effective strategies to precisely modify the optoelectronic properties of the semiconductor. Herein, we elucidated the role of a high concentration of Bi dopant on the structural and optical properties of CsPbBr3 perovskite nanocrystals. We successfully doped Bi3+ ion into the lattice of CsPbBr3 perovskite NCs through a hot-injection method and achieved a maximum of 6.91% Bi doping. The increasing amount of Bi3+ ion concentration precisely tunes the optical properties of host CsPbBr3 NCs. The spectroscopic data shows a systematic quenching of the photoluminescence and specifies doping-induced modification of the electronic band structure. Interestingly, a certain amount of BiBr3 triggers the transformation of Bi-doped CsPbBr3 NCs to lead-depleted Bi-doped Cs4PbBr6 NCs. The photodetector based on Bi-doped CsPbBr3 NCs displays a higher photo response with an impressive on-off ratio. This study offers a mechanism for the reorganization of the lead halide perovskite lattice by doping and demonstrates that Bi doping can be used to improve the performance of optoelectronic devices.