Modulating Chemical Interaction to Realize Bottom‐Up Defect Passivation for Efficient and Stable Perovskite Solar Cells

Abstract

The defects of perovskite and SnO2layers, interfacial energy barrier, and high grain boundary density impede further development of perovskite solar cells. Herein, a bottom‐up versatile modification strategy, which is implemented via introducing Lewis base ligand molecules containing different numbers of carbonyls (urea, propanedioic acid, and barbituric acid [BA]) into SnO2colloidal solution, is reported. All modifiers exhibit positive but different defect passivation effects for both SnO2and perovskite layers. The defect passivation effect can be rationally modulated by tuning the number of carbonyls and is directly proportional to the number of carbonyls. The enlargement sequence of the grain size is the same as that of the defect passivation effect. Meanwhile, the interfacial energy barrier, charge accumulation, and hysteresis are mitigated after modification, which is principally attributed to improved energy band alignment, reduced interfacial defects, and improved electrical properties of SnO2films. The BA‐modified device achieves an impressive efficiency up to 23.35%, which is significantly higher than 21.59% of the reference device. In addition, the modified devices demonstrate enhanced moisture and thermal stabilities.