Density functional theory study of mixed halide influence on structures and optoelectronic attributes of CsPb(I/Br)₃

This paper reports on the influence of the bromine (Br) atoms substitution on the structures and optoelectronic traits of ${\text{CsPbI}_3}$CsPbI₃, wherein the density functional theory (DFT) simulation was performed, using all electrons full potential linearized augmented plane-wave method. Furthermore, the generalized gradient approximation, local density approximation, and modified Becke-Johnson exchange-correlation potential were used to improve the optimization and band structure calculations. The calculated lattice constants of ${\text{CsPbI}_3}$CsPbI₃ and ${\text{CsPbBr}_3}$CsPbBr₃ were consistent with the experimental values. All the studied compounds revealed wide and direct bandgap energies at the R-symmetry point, which varied from 1.74-2.23 eV. The obtained refractive indices of the ${\text{CsPbI}_3}$CsPbI₃, ${\text{CsPbBrI}_2}$CsPbBrI₂, ${\text{CsPbIBr}_2}$CsPbIBr₂, and ${\text{CsPbBr}_3}$CsPbBr₃ compounds were correspondingly 2.265, 2.245, 2.090, and 2.086. Present findings may contribute towards the development of experimental studies on the proposed compounds with controlled properties useful for the solar cells.