Phase stability and impact of water on CsSnI₃ perovskite

Abstract

Practicability of CsSnI3 has been limited by the lack of stability in humid environment. Here we calculated phase stability, the impact of H2O embedded in CsSnI3 and surface adsorption by the first-principles calculations. Total energy results show that γ-CsSnI3 and Y-CsSnI3 are more stable. However, the γ-CsSnI3 is hydrophilic-like and Y-CsSnI3 is hydrophobic-like. γ-CsSnI3 studies show that H2O tend to adsorb at the hollow sites on the (001) surface. Strong coupling between O and Cs atoms and hydrogen bonding interactions between H and I atoms render the deformation of the (001) surface. These results are partially explained by the phase instability of perovskites in air.