A Multifunctional Molecular Bridge at the Bottom Interface of Perovskite Solar Cells for Crystallization Regulation and Efficient Carrier Extraction

Abstract

Perovskite solar cells (PSCs) have attracted widespread attention from researchers worldwide and experienced rapid development in recent years. The bottom interface plays a crucial role in charge transfer and collection, and its status significantly affect the perovskite crystallization and the performance of PSCs. Thus, in this work, potassium trifluoromethanesulfonate (KFMA), was introduced as a multifunctional molecular bridge at the SnO 2 /Perovskite bottom interface to improve the interface status and the efficiency and stability of PSCs. Our results show that KFMA can interact with SnO 2 , passivate its surface defects, and optimize the interface energy level alignment, leading to enhanced charge transfer and promoted carrier extraction. Additionally, KFMA can regulate the growth of PbI 2 and perovskite crystallization, making more thorough transformation from PbI 2 to perovskite, giving a high‐quality perovskite film. As a result, PSCs with a KFMA interface layer achieved an efficiency of 26.08% and long‐term stability. After maximum power point (MPP) tracking under 1 Sun illumination for 500 h, PCE of the KFMA‐based device remained at 82.6% of the initial efficiency, while that of the pristine PSC just was left about 40%.