Pressure effect on structures and optoelectronic attributes of mixed halide CsPb(I/Br)3: a density functional theory study.

The effect of pressure (up to 10 GPa) on the electronic and optical properties of bromine-substituted cesium lead iodide (CsPbI3), as one promising inorganic halide perovskite, is investigated using modified Backe-Johnson (mBJ) potential for the first time to our knowledge. The lattice parameters, electronic bandgap, and imaginary and real parts of the dielectric function, along with the optical absorption coefficient, are calculated. Density functional perturbation theory is employed to compute the optical properties in the photon energy range from 0.0 to 30 eV. No structural or phase-type transformation is noticed under the applied pressure, which resulted in a uniform contraction of the unit cell. Bandgap variation is seen in all the structures, with the maximum (1.65 eV) and minimum (1.46 eV) decrease found for doped and undoped CsPbBrI2, respectively. The present work provides useful information about the performance of CsPbI3-xBrx compounds under high pressure that can be utilized in designing solar cells and optoelectronics.

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.