Enhanced moisture stability of cesium lead iodide perovskite solar cells – a first-principles molecular dynamics study

Abstract

An understanding of the interaction of water with perovskite is crucial in improving the structural stability of the perovskite. Hence, in this study, the structural and electronic properties of the γ-CsPbI₃(220) perovskite surface upon the adsorption of water molecules have been investigated based on density functional theory calculations. Also, we perform first-principles ab initio molecular dynamics simulations (AIMD) to explore the structural stability of the γ-CsPbI₃(220) perovskite surface in the presence of water molecules, and the results are compared with the conventional cubic CH₃NH₃PbI₃(100) perovskite surface. The water molecules show stronger interactions with the (220) surface of γ-CsPbI₃ than the (100) surface of CH₃NH₃PbI₃. However, AIMD results demonstrate that the former is much more stable, and no trace of surface degradation was observed upon the adsorption of water molecules.