Insight into the Structures and Photophysics of Zn-Alloyed Lead Bromide Perovskite Nanocrystals Synthesized by a Post-Ion-Exchange Method and a One-Pot Hot Injection Method

Doping Zn2+ into the CsPbX3 nanocrystal is a straightforward and feasible operation, but there is still no systematic study of its structures and photophysics. Herein, we respectively fabricated two kinds of Zn-alloyed CsPbBr3 nanocrystals through a post-ion-exchange (CsPbBr3-ZnBr2-PIEX) and one-pot hot injection (CsPbBr3-ZnBr2-OPHI) method and conducted comprehensive investigations on them. It is found that the photoluminescence intensities of both CsPbBr3-ZnBr2-PIEX and CsPbBr3-ZnBr2-OPHI nanocrystals are significantly enhanced as compared to that of the pristine CsPbBr3 nanocrystal. The steady-state absorption and photoluminescence, XRD, SEM–EDX, ICP–OES, XPS, and TEM studies demonstrate that Zn2+ can be incorporated into the [PbBr6]4– framework of the CsPbBr3-ZnBr2-OPHI nanocrystal and cause its lattice contraction, while the structure of the CsPbBr3-ZnBr2-PIEX nanocrystal remains unchanged as that of a pristine CsPbBr3 nanocrystal. The femtosecond transient absorption spectroscopy studies confirm that Zn2+ incorporation into the [PbBr6]4– framework of the CsPbBr3-ZnBr2-OPHI nanocrystal has a dramatic effect on its hot carrier cooling time, biexciton Auger recombination time, and biexciton binding energy.