A comparative study of hydrostatic pressure treated environmentally friendly perovskites CsXBr3 (X = Ge/Sn) for optoelectronic applications

All-inorganic cubic cesium germanium bromide (CsGeBr3) and cesium tin bromide (CsSnBr3) perovskites have attracted much attention because of their outstanding optoelectronic properties that lead to many modern technological applications. During their evolution process, it can be helpful to decipher the pressure dependence of structural, optical, electronic, and mechanical properties of CsXBr3 (X = Ge/Sn) based on ab initio simulations. The lattice parameter and unit cell volume have been decreased by applying pressure. This study reveals that the absorption peak of CsXBr3 (X = Ge/Sn) perovskites is radically changed toward the lower photon energy region with the applied pressure. In addition, the conductivity, reflectivity, and dielectric constant have an increasing tendency under pressure. The study of electronic properties suggested that CsXBr3 (X = Ge/Sn) perovskites have a direct energy bandgap. It is also found through the study of mechanical properties that CsXBr3 (X = Ge/Sn) perovskites are ductile under ambient conditions and their ductility has been significantly improved with pressure. The analysis of bulk modulus, shear modulus, and Young’s modulus reveals that hardness of CsXBr3 (X = Ge/Sn) perovskites has been enhanced under external pressure. These outcomes suggest that pressure has a significant effect on the physical properties of CsXBr3 (X = Ge/Sn) perovskites that might be promising for photonic applications.