Reversible Color Switching in Dual-Emitting Mn(II)-Doped CsPbBr₃ Perovskite Nanorods: Dilution versus Evaporation

Postsynthesis halide treatment can brighten perovskite nanocrystals. While this has been recently explored for undoped nanocrystals having only the exciton emission, herein, the impact of halide-enriched and -deficient environments was studied for dual-emitting Mn(II)-doped CsPbBr3 nanorods. This was performed by adopting a self-regulated approach where the nanorod solution reversibly switched the color brightness from blue to orange and vice versa by dilution and evaporation, respectively. With control experiments, it was established that the color switching was not due to a change in the rate of the exciton energy transfer from host to dopant energy states; rather, it was related to self-regulated fulfilling and again creating halide vacancies observed with variation of nanorod concentration. Being that the halide vacancy was established as one of the key factors for controlling the brightness of these nanocrystals, this reversible switching in doped CsPbBr3 adds new fundamental insight into controlling the photoluminescence of these emerging nanocrystals.