High Pressure Polyhedral Interaction in Cssni3

Abstract

In recent years, metal halide perovskites have attracted great interest in various applications because of their excellent properties. Here, we find pressure-induced transformations of edge-sharing Sn−I polyhedral to face-sharing Sn−I polyhedral and subsequently to quasi-two-dimensional layer Sn-I polyhedral in CsSnI3 semiconductor phases at 5.4 GPa and 40 GPa. Our first-principles density functional theory calculations uncover that the of phase transformation is due to the variation of Sn atomic coordination accompanied by the Sn-I polyhedral distortion. Both phases are indirect band gap which is smaller than atmospheric phase. Further calculations show that intrapolyhedral Sn−Sn hybridization and interpolyhedral I−I coupling lead to the Sn-I polyhedral distortion. These findings will provide valuable insights into phase transformation of perovskites at high pressures.

Keywords: Perovskite, High pressure, Phase transition