Theoretical insights into the stability of perovskite clusters by studying water adsorption on (CH3NH3)4SnI6

Perovskite solar cells have great development prospects due to their high photoelectric conversion efficiency and low cost. However, perovskite materials are easy to decompose under water conditions, directly reducing the efficiency of perovskite solar cells. Cluster model was applied to study the mechanism of the effect of water on perovskite materials. Density functional theory has carried on to theoretically calculate the structure and energy of perovskite cluster after adsorbing water molecules. The usage of independent gradient model (IGM) showed the interaction region between perovskite cluster and water molecules. The bonding types between atoms were qualitatively obtained by analysis of atoms in molecules (AIM), and the microscopic mechanism of interaction between perovskite cluster and water molecules is revealed. The results show that when the number of the interactions between perovskite cluster and water molecules increases, the stability of the adsorption configuration will enhance. The interaction type between perovskite cluster and water molecules belongs to hydrogen bond and it also affects the stability of the perovskite cluster. This result can contribute to understand the stability of perovskite clusters by studying water adsorption on (CH3NH3)4SnI6 and to furtherly improve the practicability of perovskite solar cells.