Interface modification by ethanolamine interfacial layer for efficient planar structure perovskite solar cells

The electron transport layer (ETL) is an essential part in perovskite solar cells (PSCs), which plays a crucial role in electron-transport and hole-blocking. However, the defects and band-energy-mismatch at ETL/perovskite interface accelerate the interfacial carrier recombination, leading to severe voltage losses and hysteresis effect. Herein, a thin ethanolamine (EA) modification layer is inserted between the stannic oxide (SnO2) and perovskite layer to enhance the performance of PSCs. The results show that the hydroxyl group in EA can coordinate with the uncoordinated Sn atom of SnO2 to reduce the oxygen vacancy defects, and the amino group in EA can passivate the uncoordinated Pb2+ defects of SnO2/perovskite interface, thus inhibiting the interfacial carrier recombination. Meanwhile, the energy alignment between SnO2 and perovskite layer is better-matched after EA modification, ensuring more efficient electrons transport and minimizing energy losses. Consequently, the EA-based device exhibits an optimized PCE of 20.44% with an open-circuit voltage (Voc) of 1.134 V. In addition, the air stability of EA-based device exhibits great superiority to the control device under the same storage conditions. This interface engineering based on EA provide a feasible and novel strategy to fabricate the PSCs with improved efficiency. •EA passivated the oxygen vacancy defect and uncoordinated Pb2+ defects.•The EA-based device exhibits an optimized PCE of 20.44% with decreasing hysteresis.•The stability of EA-based device improved, retaining 78% initial PCE after 1000 h.