Insights into the effect of methylammonium orientation on the crystal structural, electronic structure and optical properties of CH3NH3SnI3

Abstract

Organic-inorganic hybrid halide perovskites have become an important new generation solar cell materials that are expected to significantly improve the solar conversion efficiency. In this work, the effect of methylammonium (CH3NH3) orientation on CH3NH3SnI3 perovskite is studied by using the first principles of density functional theory. We report the electronic and optical properties of methylammonium in different orientations. It is shown that CH3NH3 orientation leads to an increase in the absorption coefficient and complex refractive index of the material, a redshift in the absorption spectrum, and an enhanced absorption in the visible and near-infrared regions. We find that these changes are strongly influenced by organic-inorganic interactions and octahedral distortions. It suggests that the band gap and optical properties may be effectively modulated by the CH3NH3 rotation orientation, providing valuable insights into the behavior of CH3NH3 embedded in the inorganic octahedra of experiments.