Effect of introducing zinc on the photoluminescence and stability of cesium lead halide perovskite materials

Abstract

Metal halide perovskites are restricted by their stability and environmental detriment due to the participation of expensive and toxic reagents. We have selected a green dry mechanical grinding method to synthesize the perovskite materials, and with the introduction of Zn powder (CZ), most of the bulk CsPbBr3/Cs4PbBr6 phases (pure C) are converted to Cs2ZnBr4, which separates the remaining CsPbBr3 NCs to form heterostructures on the surface ZnO layer of Zn. The photoluminescence (PL) of the resultant CZ samples first increases and then decreases as the Zn dosage changes, and the PL intensity of the optimum sample with 10 mmol of Zn (CZ10) increases to about 8 times that of pure C. The largely enhanced PL of CZ10 is originated from the remaining CsPbBr3 NCs promoted by the weakened charge transfer from CsPbBr3 to Cs2ZnBr4 and the metallic Zn due to the formation of a quasi-type I heterostructure of Cs2ZnBr4/ZnO. After the calcination treatment at 700 ℃ (CZ10-C700), 80% of PL is maintained, but the photostability of CZ10-C700 is greatly enhanced compared with that of CZ10, and 99.3% of PL is kept after 150 h illumination, which is attributed to the encapsulation protection of CsPbBr3/Cs2ZnBr4 by the ZnO layer on Zn.