Effect of Cu2+ doping on fluorescence of Cs2ZnCl4 powder prepared by solid-state synthesis

Recently Cu-doped all-inorganic zero-dimensional (0D) metal halides Cs2ZnX4 (X = Cl, Br) have attracted many researchers due to their excellent fluorescence (FL) performance and low toxicity compared to lead-based perovskites. Although these 0D metal halides nanocrystals or small-sized single crystals are prepared via solution methods in most of the reports, we used the solid-state synthesis method to get Cu-doped Cs2ZnCl4 powders and characterized their FL properties. The results and analysis indicate that Cu2+ can be doped in Cs2ZnCl4 up to 12 at.%, which enhances the FL of Cs2ZnCl4 powder. The photoluminescence quantum yield (PLQY) at 480 nm rises from 1.11 % (undoped) to 20.06 % (6 at.% Cu doping). A modified triplet self-trapped excitons mechanism is presented to explain the enhanced Cu−doped Cs2ZnCl4 powder.