On the Role of Cs₄PbBr₆ Phase in the Luminescence Performance of Bright CsPbBr₃ Nanocrystals

CsPbBr₃ nanocrystals have been identified as a highly promising material for various optoelectronic applications. However, they tend to coexist with Cs₄PbBr₆ phase when the reaction conditions are not controlled carefully. It is therefore imperative to understand how the presence of this phase affects the luminescence performance of CsPbBr₃ nanocrystals_. We synthesized a mixed CsPbBr₃-Cs₄PbBr₆ sample, and compared its photo- and radioluminescence properties, including timing characteristics, to the performance of pure CsPbBr₃ nanocrystals. The possibility of energy transfer between the two phases was also explored. We demonstrated that the presence of Cs₄PbBr₆ causes significant drop in radioluminescence intensity of CsPbBr₃ nanocrystals, which can limit possible future applications of Cs₄PbBr₆-CsPbBr₃ mixtures or composites as scintillation detectors.