Buried Interface Passivation of Regular Perovskite Solar Cells Using Trimethoxysilane-Based Small Molecule Materials

Numerous issues influencing the device performance at the buried interface of perovskite solar cells exist. Modifying the interface constitutes a key to enhancing the efficiency and stability of solar cells. In this work, we propose a small molecule material, (3-bromopropyl)trimethoxysilane (BTS), as an efficient modifier for the buried interface of regular perovskite solar cells. It can interact with the -OH groups on SnO₂ and the uncoordinated Pb and the formamidinium (FA) vacancies in the perovskite, thereby passivating the defects in the SnO₂ and perovskite layers, improving the extraction and transportation of charge carriers at the interface, inhibiting the nonradiative recombination of charge carriers, and thereby increasing the carrier lifetime. The introduction of BTS significantly improves the performance of the solar cells, with the open-circuit voltage (<i>V</i>_oc) reaching 1.169 V and an increase in power conversion efficiency (PCE) from 19.39% to 23.60%. Additionally, the devices with interface modification exhibit outstanding stability, retaining 85.7% of the initial PCE value after being aged for 160 days under a relative humidity of 35% at room temperature.