Multifunctional Anti‐Corrosive Interface Modification for Inverted Perovskite Solar Cells

Abstract The interface stability and non‐radiative recombination loss of the cathode interface greatly limit the stability and performance of inverted perovskite solar cells (PSCs). Here, an efficient multifunctional anti‐corrosive interface modification strategy based on 2,2′‐(1,3‐phenylene)‐bis[5‐(4‐tert‐butylphenyl)‐1,3,4‐oxadiazole] (OXD‐7) is proposed to overcome the cathode interface issues. OXD‐7 molecules chemically coordinate to the Ag electrode and form a chemically stable complex film of OXD7‐Ag, which suppresses halide ion migration and thus enhances the corrosion resistance of the electrode as well. In addition, the trap density of perovskite film, PCBM/Ag interfaces contact, the built‐in potential, moisture resistance, as well as the unfavorable interface exciton dissociation elimination of the devices, are also improved with the OXD‐7 arrangement upon PCBM film, which correspondingly enhances the device performance and stability. Bidirectional halide ion migration and the ITO corrosion are observed, which is also suppressed by the OXD‐7 modification. The high power conversion efficiency (PCE) of 21.84% and the high fill factor (≈84.63%) is obtained via this strategy, which is one of the highest PCEs and FFs based on solution‐process MAPbI 3 /PCBM heterojunctions. The PCE can maintain ≈80% of its initial value after 1080 h at 85 °C with OXD‐7 modification.