Trimming Defective Perovskite Layer Surfaces for High-Performance Inverted Inorganic Solar Cells

Inverted inorganic perovskite solar cells (IPSCs) with a bandgap of about 1.7 eV are prospective candidates for the next generation of photovoltaic cells due to their elemental composition and unparalleled light and thermal stability. However, the higher defect state density and energy level mismatch at the interface result in inferior photovoltaic performance to that of organic-inorganic hybrid perovskite solar cells. Herein, 4-fluorobenzylamine hydrochloride (p-F-PMACl) is introduced as the interface to manage these issues for efficient inverted IPSCs. It is revealed that active chlorine (Cl) sites interact with lead (Pb) on the surface to repair iodine atoms vacancy (V_I) defects. The fluorine (F) site of p-F-PMACl interacts with Pb to correct the octahedral lattice anomaly change and eliminate the Pb-I defects. Moreover, the introduction of p-F-PMACl optimizes the level arrangement, reducing the density of defect states and suppressing nonradiative recombination. Consequently, upon achieving a champion power conversion efficiency (PCE) of approximately 21%, the record open-circuit voltage (V_OC) deficit is 446 mV. In addition, a PCE of 18.91% is demonstrated for IPSCs with a bandgap of 1.77 eV, yielding a V_OC exceeding 1.31 V.