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 (SnO 2 ) 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 SnO 2 to reduce the oxygen vacancy defects, and the amino group in EA can passivate the uncoordinated Pb 2+ defects of SnO 2 /perovskite interface, thus inhibiting the interfacial carrier recombination. Meanwhile, the energy alignment between SnO 2 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 (V oc ) 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 Pb 2+ 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.