Structurally Optimized MPAC Oxygen‐Heterocycle‐Based Interface Defect Passivators for Stable Spiro‐OMeTAD‐Enhanced PSCs

The substantial energy loss and poor stability of perovskite solar cells (PSCs) are the primary obstacles to their commercial development. Among them, the defects at the surface interface of the perovskite layer are the main reason for the low power conversion efficiency (PCE) and the poor stability of the device. In order to passivate the surface interface defects of perovskite and enhance the device efficiency and stability, three small molecules, MPAC‐PR , MPAC‐TP , and MPAC‐TT , are developed in this work as the interfacial layer materials for n‐i‐p structured PSCs. These interfacial layer materials exhibit excellent thermal stability and charge transport capability. The perovskite layers treated by interfacial layers have higher film quality. The devices based on the three interfacial layer materials, MPAC‐PR , MPAC‐TP , and MPAC‐TT , have more excellent photovoltaic performance, with PCE of 23.14%, 23.64% and 22.94% relative to the standard devices of 21.93%, respectively. Meanwhile, the hydrophobicity of the interfacial layer endows the better stability of device in the air due to the formation of heterojunctions by perovskite and PbI 2 . The results show that this molecule acts as a bifunctional layer in the PSC due to its combination of outstanding ability to passivate defects and excellent compatibility with Spiro‐OMeTAD.