High‐Efficiency and Stable Perovskite Solar Cells via Buried Interface Modification with Multi‐Functional Phosphorylcholine Chloride

Abstract The electron transport layer (ETL), perovskite layer, hole transport layer, and electrode layer collectively constitute the perovskite solar cells (PSCs). Each of these layers plays a critical role in the performance of devices. However, there are mismatches in crystal structure and energy levels between ETL materials and the perovskite layer, resulting in numerous defects at their interface. In this study, multifunctional organic molecule called phosphorylcholine chloride is designed to modify the interface between SnO 2 and perovskite layer. This modification serves to both reduce oxygen vacancy defects in the SnO 2 and passivate defects in the perovskite layer. Consequently, the conductivity and electron mobility of SnO 2 are improved, and the higher‐quality of perovskite film is obtained. Ultimately, the optimized PSC device achieves an impressive champion power conversion efficiency (PCE) of 24.34% with minimal hysteresis index. Even after 1200 h of ambient exposure at 25 °C and 25% relative humidity without encapsulation, the device maintains an impressive 91.44% of its initial efficiency. Additionally, a PCE of 22.38% is attained in flexible PSCs. This research will pave the way for the development of low interface defects, high stability as well as high PCE perovskite solar cells.