Dual-site regulation approach for improving photoelectric performance of perovskite solar cells

High power conversion efficiency (PCE) and long-term stability are the keys to the commercialization of perovskite solar cells (PSCs). However, the defects of formamidinium lead tri-halide (FAPbI 3 ) perovskite films limit the PCE of the device to the Shockley Queisser limit. The conventional strategies for enhancing the properties of perovskite films often pivot on the selective interaction between a passivating agent and a solitary constituent within the perovskite matrix. Herein, we present an alternative dual-site regulation approach using 6-fluorobenzamide (6-FB) to modulate the reaction kinetics of Pb and I, resulting in FAPbI 3 films with fewer defects and significantly enhanced carrier lifetimes. 6-FB can not only passivate the uncoordinated Pb 2+ defects and iodine vacancies. The optimized PSCs achieved a PCE of 25.03 % (certified at 24.25 %) with an area of 0.0625 cm 2 , and retained 94.1 % of their initial PCE after storage in ambient air (∼10 relative humidity, RH) for over 800 h. This method expands the scope of chemical interactions possible by leveraging the interaction between 6-FB and the perovskite.