Achieving Multicolor Emitting of Antimony-Doped Indium-Based Halide Perovskite via Monovalent Metal Induced Phase Engineering

Lead-free metal halide perovskites have attracted attention because of their excellent optical properties and nontoxicity. Here, we report the synthesis of Sb³⁺-doped indium halide perovskite Cs₂InCl₅·H₂O:Sb³⁺ by an improved solution coprecipitation method. The treatment of the Sb³⁺-doped indium halide perovskite with selected monovalent cation halides led to Cs₂MInCl₆ (Ag⁺, K⁺, Na⁺) in different crystal structures or phases. Sb³⁺ has an isolated ns² electron, and Sb³⁺-doped metal halide acts as the luminescence center and exhibits bright broadband emission that originated from self-trapped excitons. Under UV light excitation, these phosphors with different crystal structures emitted multicolored luminescence ranging from blue, green, yellow, and red depending on whether or not or which monovalent metal ion was used. The phosphor samples were used to print high-resolution 2D color barcodes for security and anticounterfeiting applications. The study presented here provides a new approach for the design and synthesis of lead-free metal halide perovskites with different crystal structures and unique optical properties.