Lead‐Free Perovskite Variant Solid Solutions Cs2Sn1–xTexCl6: Bright Luminescence and High Anti‐Water Stability

Abstract Underwater lighting is important for the exploration of the underwater world in different areas. It is of great significance for developing underwater emitters with high penetrability, high luminous efficiency, good anti‐water stability, and environmental friendliness. Stable lead‐free perovskite luminescent materials, represented by vacancy‐ordered double perovskites, are worthy of research because they can almost meet the above requirements. Here, lead‐free perovskite variant solid solutions with the formula of Cs 2 Sn 1− x Te x Cl 6 are reported. Upon the exchange of Sn/Te ions, strong Jahn–Teller distortion of octahedra occurs in the lattice structure. The combination of Te luminescent center and Jahn–Teller‐like self‐trapped excitons gives this material yellow‐green luminescence with a wavelength of 580 nm and a high photoluminescence quantum yield of 95.4%. Moreover, these solid solutions can withstand the extreme conditions of immersion in water probably due to the formation of amorphous alteration phase. Such good anti‐water stability is also supported by the molecule dynamics simulation result that no reaction occurs on the water/Cs 2 SnCl 6 interface. The high luminous, suitable wavelength, and good anti‐water stability enable the solid solutions suitable for the application for underwater lighting.