Dual-site molecule induced multifunctional surface modulation for highly efficient and stable inverted perovskite solar cells

Surface defect passivation is an effective method to enhance the efficiency and stability of perovskite solar cells (PSCs). This study employs a dual-site molecular 2MTEAC-based surface passivation method to improve the photovoltaic performance of PSCs. Theoretical calculations indicate that when the S and N of 2MTEAC act on the perovskite surface simultaneously, the binding interaction could be improved, and the optimized configuration reveals the synergistic dual-site passivation effect of 2MTEAC. Experimental characterizations confirm that the 2MTEAC molecule mitigates uncoordinated Pb defects and halide vacancies at the interface, passivates defects, improves lattice strain and forms a n-type interface contact with the perovskite, thereby optimizing the energy level alignment at the interface and promoting charge carrier transport. As a result, PSCs with 2MTEAC achieved a PCE of 24.52 %. Additionally, the devices treated with 2MTEAC exhibit improved stability, maintaining 90 % of their original PCE after thermal annealing at 85 °C for 1000 h in N₂ glove box, and retaining 85 % of their initial PCE in a humid conditions with a relative humidity of 60 ± 10 % over 1000 h. Therefore, the dual-site molecular surface passivation strategy provides an effective approach to improving the efficiency and stability of PSCs.