Hot-Injection Synthesis of Bi³⁺ and Zn²⁺ Co-Doped CsPbBr₃ Nanocrystals with Enhanced Photoluminescence Quantum Yield

Lead halide perovskites have attracted significant attention for optoelectronic applications due to their exceptional photoluminescence efficiency. Previous studies have shown that doping strategies can reduce defect density and improve carrier dynamics. However, the synergistic influence of Bi³⁺ and Zn²⁺ co-doping on charge carrier density and surface defect passivation remains unexplored. In this work, cesium lead bromide nanocrystals were synthesized using the hot-injection method at 160 °C to investigate this Bi³⁺ and Zn²⁺ co-doping strategy. Notably, the optimally co-doped sample achieved a photoluminescence quantum yield of 96.1 %, surpassing 88.2 % of undoped CsPbBr₃. A blue shift in emission from 510.5 nm to 504.5 nm and a modest bandgap increase from 2.407 eV to 2.425 eV were observed. Time-resolved photoluminescence measurements revealed a shorter average lifetime, from 9.51 ns to 5.71 ns, consistent with a higher radiative recombination rate and suppressed non-radiative decay. These results confirm that Bi³⁺ and Zn²⁺ co-doping effectively passivates trap states and enhances exciton dynamics, providing a new pathway to achieve high quantum yield in perovskite nanocrystals and offering strong potential for next-generation high-efficiency light-emitting devices.