2,2'-Dihydroxy-4,4'-dimethoxy-benzophenon as Bifunctional Additives for Passivated Defects and Improved Photostability of Efficient Perovskite Photovoltaics.

Organic-inorganic hybrid perovskite solar cells (PSCs) have developed rapidly in the past decade, but their commercial applications are restricted by further improvement in their photovoltaic performance and stability. Herein, we propose a facile and effective method employing 2,2'-dihydroxy-4,4'-dimethoxy-benzophenon (BP6) as bifunctional additive to construct efficient and photostable PSCs. BP6, as an additive, improves the crystallization quality of perovskite absorbers and further inhibits defect-mediated non-radiative recombination through interaction between the C═O group and defects; as a UV absorber, BP6 protects the PSCs from UV degradation by effectively absorbing UV light through molecular tautomerism under continuous strong UV irradiation. Eventually, the champion PSC demonstrates an efficiency of 22.85% with enhanced UV stability after addition of 0.024 wt % BP6. These results reveal that addition of UV absorbers (such as BP6 in this study) is a simple and effective strategy to fabricate efficient and photostable PSCs.