Interface engineering is vital for optimizing charge transport, stability, and overall efficiency in perovskite solar cells. In this work, two novel fluorinated bathocuproine (BCP) derivatives, BCP-m2F and BCP-m4F, are introduced, featuring site-selective monofluorination at the terminal phenyl rings. Compared to the previously reported BCP-m1, which incorporates aryl substitution for improved planarity and charge transport, these new derivatives leverage fluorination to further tailor the electronic structure and interfacial behavior. The energy-level modulation by fluorination plays only a minor role; however, fluorination significantly enhances device stability through stronger binding with C₆₀ and a pronounced surface passivation effect. Experimentally, BCP-m4F demonstrates superior film uniformity and conductivity compared to BCP-m2F. Time-resolved photoluminescence, J-V analysis, contact angle measurements, and damp heat stability test (ISOS-D3) show improved charge extraction, reduced trap-assisted recombination, increased hydrophobicity, and enhanced thermal and moisture stability, respectively. Notably, a device employing BCP-m4F exhibits minimal open-circuit voltage loss under low-light conditions, highlighting its suitability for indoor or diffuse-light applications. These findings underscore the potential of combining rational backbone design with targeted fluorination to achieve multifunctional interlayers that enhance performance and reliability in next-generation perovskite solar cells.