Building a UV filter and interfacial bridge with a multifunctional molecule for enhancing the performance and stability of MAPbI3 solar cells

Perovskite solar cells (PSCs) are considered one of the most promising photovoltaic technologies. However, their modest stability remains a major obstacle to their development, especially with regard to ultraviolet (UV) light damage, and has received increasing attention and should not be underestimated. In this study, we address this issue by introducing a well-designed BP-4 molecule (2-hydroxy-4-methoxybenzophenone-5-sulfonic acid) that simultaneously improves the UV stability and interface electrical properties of PSCs, resulting in high-efficiency and stable devices. BP-4 acts as a UV filter that inhibits perovskite degradation, essentially improving the UV stability of PSCs. Additionally, BP-4 bridges the perovskite and SnO2 layers by forming an [Sn4+]-[BP-4]-[Pb2+] electron transfer channel (ETC), which enhances interface electron transport and passivates interface defects, inhibiting defect-induced photodegradation of the devices. As a result, BP-4-based PSCs exhibit an efficiency of 21.01%. More importantly, after 6 hours of 365 nm UV irradiation, the BP-4-based device retains 75% of its initial efficiency, which is much better than that of the control device. These results suggest that small molecule UV absorbers, such as BP-4, hold great promise for promoting the development of commercialized and environmentally friendly perovskite solar cells.