Effect of pressure on the mechanical, electronic and optical characters of CsSnBr3 and CsSnI3: ab-initio study

A theoretical comprehensive implementing of the structural, elastic, electronic and optical properties of CsSnX3 (X = Br and I) perovskite compounds under pressures 0 and 20 GPa is performed by ab-initio calculations included within the density functional theory (DFT). The structure of crystal perovskite compounds is found to be stable under induced pressure. The compounds have shown a decrease in the structural properties such as lattice constant and interatomic bond length when the pressure was induced. Whereas, there was an increase in the thermodynamic properties such as Debye temperature and average velocities of sound when pressure was induced. Moreover, the values of mechanical parameters, such as the elastic constant, increased under applied pressure. The electronic parameters indicate that the compounds can be classified as semiconductor materials with a direct (M-M) gap. The induced pressure is found to enhance the optical parameters in the different energy regions. Our calculation predicts that the studied compounds can be the relevant candidates in optical, thermoelectric and mechanical applications.