High efficiency carbon-based CsPbI2Br solar cells achieved by bidirectional passivation of cadmium p-aminobenzoate

The tin dioxide (SnO 2 ) layer is commonly used as a traditional electron transport layer (ETL) in perovskite solar cells. However, it exists numerous defects in interior and on surface, diminishing the electron transport rate and causing energy level mismatches, thereby limiting the photoelectric conversion efficiency (PCE). In this study, cadmium p-aminobenzoate (PABACd) is synthesized using the displacement reaction and applied to modify the interface between the SnO 2 ETL and CsPbI 2 Br film to achieve bidirectional passivation. Cd 2+ effectively passivates defects in the ETL and penetrates perovskite crystals, contributing to defect passivation. Furthermore, PABA − stabilizes the [PbX 6 ] 4− octahedron, enhancing the stability of CsPbI 2 Br perovskite solar cells (PSCs). As a result of these interactions, the PABACd-optimized device achieved a maximum PCE of 14.34 % and an outstanding open-circuit voltage of 1.27 V. Simultaneously, the PCE of the optimized CsPbI 2 Br PSCs remains at 92 % of the initial efficiency after 30 days of aging in an air environment with 15–20 % humidity.