F-doping-Enhanced Carrier Transport in the SnO₂/Perovskite Interface for High-Performance Perovskite Solar Cells

SnO₂ is widely used as the electron transport layer (ETL) in n-i-p perovskite solar cells. However, the deep-level defects at the interface between SnO₂ and the perovskite film will lead to energy loss, reducing the open-circuit voltage. Therefore, the interface optimization is essential to raise the efficiency and enhance the stability of perovskite solar cells. In this work, we introduce NH₄F into the SnO₂ electron transport layers, and the optimized SnO₂ films reduce the interface defect density, improve the charge extraction, and reveal a better energy-level arrangement. Compared to the conventional SnO₂ perovskite solar cell, the average V_oc is improved by 70 mV with the champion efficiency up to 22.12%. Moreover, the unencapsulated F-doped SnO₂ perovskite solar cells show better thermal stability (maintained 86.2%) and humidity stability (maintained 80.8%) after 35 days.