Bright luminescence of Sb doping in all-inorganic zinc halide perovskite variant

Halide lead perovskites are considered as one of the most promising optoelectronic materials in decades, but the toxicity and bio-accumulation of lead retard the commercialization. Therefore, seeking suitable lead-free perovskites and their variants are of vital importance. In this work, all-inorganic zinc halide perovskite variant Cs2ZnCl4 crystals with Sb3+ doping are synthesized via hydrothermal method. Transparent millimeter-sized crystals exhibit bright red photoluminescence (PL) under room temperature (RT) on account of self-trapped exciton (STE) emission of Sb3+, from 3P1 to 1S0 states. Temperature-dependent PL and time-resolved PL exhibit bimodality and intensity variations, revealing that Jahn-Teller effect of 3P1 state results two energy minima, and thermal activation may contribute to the spectrum change. Further, DFT calculations are carried out and the influences of Sb3+ doping are revealed. A bandgap reduction is achieved via doping, and the band edges are localized at Sb3+. A combination of experimental and theoretical studies demonstrates well that the soft lattice structure and the 5s2 lone pairs of Sb are vital for the STE emission.