Tetramethylammonium hexafluorophosphate interface modification for high-efficiency perovskite solar cells

Interface modification has been proved to be an effective method to improve the performance of perovskite solar cells (PSCs). In this paper, tetramethylammonium hexafluorophosphate (TMAPF6) is employed to modify the interface of SnO2/perovskite. Fluorine (F) in PF6 − will fill the oxygen vacancy by interacting with Sn in SnO2. Meanwhile, TMA+ and PF6 − in TMAPF6 will effectively fill the MA+ and I− vacancy in the interface. TMAPF6 modification enhances the hydrophobicity of the SnO2 surface, promotes the growth of high-quality perovskite film with large grain size, and then significantly suppresses the non-radiative recombination of PSCs. Furthermore, the TMAPF6 modification introduces a better energy level alignment between SnO2 and perovskite layer, enabling a more efficient electron extraction. As a result, the TMAPF6-modified MAPbI3 PSC achieves a significantly increasing power conversion efficiency (PCE) from 18.62% to 20.92% and an improved stability with only 15% PCE drop after 600 h of storage in air. This work develops an efficient interface modification molecule to increase the efficiency of PSCs, which would be a promising strategy for the large-scale commercialization of the photovoltaic devices.