Simultaneous Enhancement of Efficiency and Stability in Perovskite Solar Cells via Perfluoroadipic Acid Incorporation

Abstract The two-step sequential deposition method is widely employed in the production of high-performance perovskite solar cells (PSCs). Nevertheless, the dense morphology of the pre-deposited PbI2 layer often restricts the penetration of the organic halide salt solution applied in the subsequent step. To overcome this limitation, we introduced perfluoroadipic acid (PFAA) as an additive into the PbI2 precursor solution. Both theoretical computations and experimental evidence reveal that PFAA interacts with PbI2 via its oxygen and fluorine atoms, leading to the formation of a porous PbI2 framework. This structural modification facilitates larger grain growth, diminishes trap-state density, and optimizes the band alignment of the resulting perovskite films. Consequently, the power conversion efficiency (PCE) of PFAA-modified devices is elevated from 20.71 to 22.60%, relative to the unmodified counterparts. Furthermore, the inclusion of PFAA markedly improves device longevity: after 45 days of ambient exposure, the PFAA-treated PSCs maintain 80.2% of their initial efficiency, whereas the control devices retain only 60.7%.