First-principles study of structural and optoelectronic properties of CsSnI3−yFy (y = 0, 1, 2, 3) perovskites

The halide perovskites are attractive for solar cells due to their excellent power conversion efficiency and low cost. The structural properties of Sn-based halide perovskites CsSnI 3− y F y ( y = 0, 1, 2, 3) are investigated using first-principles calculation based on density functional theory. The computed electronic structure profile reveals that these materials exhibit semiconducting behavior. The energy gap value of CsSnI 3 is tuned by substituting fluorine atom for iodine atom. It is observed that when the halogen atom fluorine is substituted for iodine atom in CsSnI 3 , the energy gap values are changed. As the pressure is increased, the energy gap value of these materials decreases and at high pressure, a semiconductor to metallic transition is observed. The optical properties of these Sn-based compounds indicate that these materials may be the effective candidates for the solar cell applications.