Bidirectional Passivation for Highly Efficient and Stable CuSCN-Based Perovskite Solar Cells Using (3-Mercaptopropyl)trimethoxysilane

Cuprous thiocyanate (CuSCN) is a promising inorganic hole-transporting material for perovskite solar cell (PSC) applications due to its robust thermal stability and high hole mobility. However, challenges arise from the use of polar sulfide solvents, such as diethyl sulfide (DES), during CuSCN film deposition. The DES residue in the solution-processed CuSCN film adversely affects the perovskite layer, leading to compromised perovskite/CuSCN interface contact and thereby impacting the photovoltaic performance and long-term stability of CuSCN-based PSCs. Herein, we propose using (3-mercaptopropyl)trimethoxysilane (MPTMS) as a passivator at the perovskite/CuSCN interface to mitigate these challenges. Inspiringly, MPTMS not only heals the perovskite/CuSCN interface but also passivates undercoordinated Pb2+ centers on the perovskite surface, serving as a bidirectional passivator at the perovskite/CuSCN interface. The MPTMS-treated CuSCN enhances the VOC of the device, resulting in a remarkable power conversion efficiency of 19.85%, a robust device stability of 93%, and 65% power conversion efficiency retention after 1000 h of aging tests under room temperature and 85 °C.