Crystallization and Defect Regulation in Sn–Pb Perovskite Solar Cells via Optimized Anti‐Solvent Passivation Strategy

Low bandgap tin–lead halide perovskite (PVSK) presents promising opportunities for high‐performance solar cells. However, the randomly crystallized Sn–Pb PVSK with a tin‐rich surface is easily oxidized, leading to high‐level p‐type doping, which hinders the performance enhancement of the solar cell devices. Herein, an efficient anti‐solvent passivation strategy to regulate defect, crystallization, and energy conversion performance based on anti‐solvents composed of chlorobenzene, isopropanol, and methylammonium chloride (MACl) is proposed. It is shown that the Sn–Pb PVSK film gets more moderate and order, with less PbI 2 and more α‐phase PVSK formed. Furthermore, it is revealed that the surface of the as‐processed film is Pb‐rich, demonstrating a decrease in the surface p‐type concentration, which is more suitable for the photoelectric conversion enhancement of the inverting device. Finally, the MACl‐assisted post‐treated Sn–Pb PVSK invert solar cells exhibit a high current density of 26.49 mA cm −2 with a open‐circuit voltage of 0.70 V and a power conversion efficiency of 16.05%. The modified anti‐solvent process fuses the advantage of additive and anti‐solvent engineering for growing highly crystallized hybrid tin‐lead halide PVSK for photovoltaic devices.