Low-Cost Hydroxyacid Potassium Synergists as an Efficient In Situ Defect Passivator for High Performance Tin-Oxide-Based Perovskite Solar Cells.

Perovskite solar cells (PSCs) based on SnO2 electron transport layers have attracted extensive research due to their compelling photovoltaic performance. Herein, we presented an in situ passivation of SnO2 with low-cost hydroxyacid potassium synergist during deposition to optimize interface carrier extraction and transport of PSCs for high power conversion efficiency (PCE) and stabilities. The orbital overlap of the carboxyl oxygen with the Sn atom alongwith the nano particle depositon effectively suppresses the interfacial defects and releases the internal residual strains in the perovskite. Accordingly, a PCE of 24.91% and fill factor (FF) up to 0.852 of in situ passivated devices are obtained, which is one of the highest values for SnO2-based PSCs. Moreover, the unencapsulated device maintained 80% of its initial PCE at 80°C over 600h, 100% PCE after aging at ambient conditions for 1300h, and 98% after one week under maximum power point tracking (MPPT) of continuous AM1.5G illumination.