Efficient Inverted Perovskite Solar Cells with a Fill Factor Over 86% via Surface Modification of the Nickel Oxide Hole Contact

Abstract The poor interface quality between nickel oxide (NiO x ) and halide perovskites limits the performance and stability of NiO x ‐based perovskite solar cells (PSCs). Here a reactive surface modification approach based on the in situ decomposition of urea on the NiO x surface is reported. The pyrolysis of urea can reduce the high‐valence state of nickel and replace the adsorbed hydroxyl group with isocyanate. Combining theoretical and experimental analyses, the treated NiO x films present suppressed surface states and improved transport energy level alignment with the halide perovskite absorber. With this strategy, NiO x ‐based PSCs achieve a champion power conversion efficiency (PCE) of 23.61% and a fill factor of over 86%. The device's efficiency remains above 90% after 2000 h of thermal aging at 85 °C. Furthermore, perovskite solar modules achieve PCE values of 18.97% and 17.18% for areas of 16 and 196 cm 2 , respectively.