First-principles computations on the structural, elastic, mechanical, electronic, optical, and thermal properties of doped halide perovskites CsSnCl3-xBrx (x = 0, 1, 2, 3) with cubic and tetragonal symmetries: A (DFT-GGA-mBJ)-based investigation

Doped halide perovskites CsSnCl_3-xBr_x (x = 0, 1, 2, 3) with semiconductor nature are promising inorganic materials for solar cells and photovoltaics and other optoelectronic devices, having high absorption and structural stability and less toxicity. Herein, we have investigated the structural, elastic, mechanical, thermal, optical, and electronic properties of CsSnCl_3-xBr_x using GGA-PBE and TB-mBJ approximations. The crystal structure of CsSnCl_3-xBr_x with cubic (Pm-3 m) and tetragonal (P4/mmm) symmetries depends on the x value, which influences their essential physical properties. The computed lattice constants are in good agreement with the previous reports. The results obtained in this study show that all these CsSnCl_3-xBr_x have semiconductor nature with a direct band gap that lies in the visible range ($E_g$ = 0.895–1.749 eV). All compounds of CsSnCl_3-xBr_x are mechanically stable with inherent ductility and a Debye temperature ${\theta }_D$ of 97.4–171.1 K. Also, the optical computations reveal high absorption power in the visible-ultraviolet range.