The effect of oxygen molecule adsorption on lead iodide perovskite surface by first-principles calculation

Abstract Oxygen molecule has a negative effect on perovskite solar cells, which has been investigated experimentally. However, detailed theoretical research is still rare. This study presents a microscopic view to reveal the interaction mechanism between O 2 and perovskite based on the first-principles calculation. The results show that O 2 is adsorbed on the (100) surface of MAPbI 3 perovskite mainly by Van der Waals force. O 2 adsorption makes the MAPbI 3 surface generate a small number of positive charges, which leads to the increase of the work function of the MAPbI 3 surface. This is in agreement with the experimental measurement. And increased work function of MAPbI 3 surface is not beneficial to electron transfer from perovskite to electronic extraction layer (such as TiO 2 ). Comparison of the density of states (DOS) of the clean (100) surface and the adsorbed system shows that an in-gap state belonging to O 2 appears, which can explain the phenomenon observed from experiments that electron transfers from the surface of perovskite to O 2 to form superoxide. The theoretical power conversion efficiency of the system with and without O 2 adsorption is evaluated, and it turns out that the power conversion efficiency of the system with O 2 adsorption is slightly lower than that of the system without O 2 adsorption. This result indicates that avoiding the introduction of O 2 molecules between perovskite and electronic extraction layer is beneficial to the perovskite solar cell.