Composition dependent optical, structural and photoluminescence characteristics of cesium tin halide perovskites

In this article we report the structural and optical properties of varying compositions of lead free inorganic perovskite (CsSnX3 (X = Br, Cl, I)) and its tunable photoluminescence covering the entire visible to near-IR region. Optical band gap studies for prepared inorganic cesium tin halide compositions show a significant (53.5%) blue shift in the absorption spectra as the halide composition varies from I to Br and Cl. As the halide composition was varied from Cl to I, an intense and tunable PL emission was observed at room temperature covering a wide range from Vis-near IR region (420-950 nm). X-ray diffraction studies revealed that undoped compositions were orthorhombic (CsSnI3), cubic (CsSnBr3) and monoclinic (CsSnCl3) in structure at room temperature. For mixed halides, the lattice constant was found to increase gradually as the size of halide cation increases from Cl- to Br- and I-.