Structural, elastic, electronic and optical properties of RbPbI3 perovskites studied using ab-initio calculations

We investigate the structural, elastic, electronic and optical properties of RbPbI3 perovskites using density functional theory calculations. The elastic properties such as elastic constants, bulk modulus, shear modulus, anisotropy factor and Poisson's ratio were calculated. The orthorhombic structure of RbPbI3 is mechanically stable and exhibits elastic anisotropy. The band structure and state density calculations based on the PBEsol + mBJ method show that this compound has a direct bandgap of 2.815 eV in agreement with the experimental value. However, the inclusion of the spin-orbit coupling into the calculations (mBJ + SOC approximation) reduces the bandgap energy to 2.457 eV. The optical properties of RbPbI3 such as the optical absorption, refractive index, extinction coefficient and dielectric function, were found to present slight anisotropy. Furthermore, the effect of pressure on some physical properties was studied, in which we show that the width of the bandgap and optical absorption depend significantly on the applied stresses to the material.