Air-Stable, Lead-Free Zero-Dimensional Mixed Bismuth-Antimony Perovskite Single Crystals with Ultra-broadband Emission.

Lead-free zero-dimensional (0D) organic-inorganic metal halide perovskites have recently attracted increasing attention for their excellent photoluminescence properties and chemical stability. Here, we report the synthesis and characterization of an air-stable 0D mixed metal halide perovskite (C8 NH12 )4 Bi0.57 Sb0.43 Br7 ⋅H2 O, in which individual [BiBr6 ]3- and [SbBr6 ]3- octahedral units are completely isolated and surrounded by the large organic cation C8 H12 N+ . Upon photoexcitation, the bulk crystals exhibit ultra-broadband emission ranging from 400 to 850 nm, which originates from both free excitons and self-trapped excitons. This is the first example of 0D perovskites with broadband emission spanning the entire visible spectrum. In addition, (C8 NH12 )4 Bi0.57 Sb0.43 Br7 ⋅H2 O exhibits excellent humidity and light stability. These findings present a new direction towards the design of environmentally-friendly, high-performance 0D perovskite light emitters.