Defect passivation with bromine template for efficient perovskite solar cells

Interfacial modification is an effective method to improve the performance of perovskite solar cells (PSCs). However, defects in SnO2 itself and interfacial defects with perovskite (PVK) lead to the limited performance of PSCs. In this study, 3, 5-dibromobenzoic acid (3,5-DBBA) material was added at the interface between electron transport layer (ETL)and perovskite absorption layer. It was found that Br in 3,5-DBBA can passivate the oxygen vacancies and uncoordinated Sn4+ defects in SnO2, and optimize the interface contact between ETL and perovskite film, inhibit the non-radiative recombination of charge carriers, and improve the carrier lifetime and extraction yield. Br is also able to interact with the perovskite lattice to passivate Pb2+ defects and regulate the crystal growth of the perovskite. The open circuit voltage of perovskite solar cells was increased from 1.12 V to 1.16 V, and the power conversion efficiency was increased from 19.19 % to 22.27 %. The bromine templates strategy can also effectively improve the stability of PSCs. It provides a new strategy for realizing high performance perovskite solar cells.