Aniline-Fluoroalkyl Interfacial Passivation Enables Defect-Suppressed and Moisture-Resistant Perovskite Solar Cells

It is inevitable that the solution process induces imperfect crystal and rich deep/shallow-level defects in the perovskite layer for the fabrication of perovskite solar cells (PSCs). These fatal issues hinder the development of high efficiency and mass production. Here, we report a bifunctional surface-passivation strategy using m -bis(trifluoromethyl)aniline ( m TFMA) at the perovskite/hole-transport-layer interface. The Lewis-basic aniline nitrogen interacts with under-coordinated lead sites, while the fluorinated aromatic framework improves surface hydrophobicity and interfacial compatibility. After m TFMA surface treatment, the perovskite film becomes pinhole-free and exhibits stronger steady-state photoluminescence. The average carrier lifetime is prolonged from 529.7 to 2479.4 ns, while the trap-state density is reduced from 1.25 × 10 15 to 7.73 × 10 14 cm −3 . Consequently, the optimized m TFMA-treated device delivers an 11.9% improvement in PCE compared with the control cell. Light-intensity-dependent V OC, impedance spectroscopy, and hysteresis analysis confirm that m TFMA suppresses trap-assisted recombination and interfacial charge accumulation. Relative to the conventional phenethylammonium iodide treatment, m TFMA provides more effective trap suppression, smoother surface morphology, higher hydrophobicity, and superior photovoltaic performance. This work highlights fluorinated aniline molecules as promising nonammonium interfacial modifiers for efficient and stable PSCs.