Enhancing perovskite quality and energy level alignment of TiO2 nanorod arrays-based solar cells via interfacial modification

Abstract The perovskite quality and energy level alignment are critical for achieving high-performance and stability perovskite solar cells (PSCs). In this work, ultrathin anatase TiO 2 were in-situ deposited on rutile TiO 2 nanorod arrays (NAs) by a room-temperature solution method, contributing to form Type-II band alignment and accelerate interfacial charge transfer in PSCs. Then, a self-assembled monolayer (SAM) of N-[3-(Trimethoxysilyl)propyl]ethylenediamine was grafted on the surface of rutile@anatase TiO 2 coaxial NAs (TCNAs). Interestingly, the power conversion efficiency (PCE) of PSCs was significantly improved to 14.89%, compared to 11.8% of the pristine TCNAs-based devices. The results indicate that the SAM controls the TiO 2 surface wettability to improve the morphology and crystallinity of the following deposited perovskite layers. Moreover, the electric dipoles from the SAM increase the Fermi level of TiO 2 for further enhancing the energy level alignment with perovskite layers to improve the interfacial charge transfer.