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 Bi_0.57 Sb_0.43 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 Bi_0.57 Sb_0.43 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.