Fluorine substitution in hydrogen-bonded organic frameworks for triboelectric sensing: structure-property relationship and mechanistic understanding

Fluorination has been demonstrated as an effective strategy to enhance triboelectric output. However, a systematic investigation into the role of fluorine content and substitution effect remains lacking. In this study, by in-situ embedding fluorine-functionalized hydrogen-bonded organic frameworks (HOFs) into poly(vinylidene fluoride-hexa-fluoropropylene) (PVDF-HFP) nanofibers via electrospinning, we explored the fluorine content and substitution effect on tribo-sensor performance. Owing to the enhanced dielectric constant and surface charge polarization, the resulting PVDF-HFP/HOF nanofibers exhibited significantly improved triboelectric performance. Notably, tribo-sensors based on fluorine-functionalized HOF-doped nanofibers delivered a maximum open-circuit voltage of 210.7 V, far surpassing that of pristine PVDF-HFP (66.9 V). Theoretical simulations further revealed that this superior performance originates from the increased molecular dipole moments and local electrostatic potentials induced by fluorine substitution, with ortho-substitution offering stronger polarization than para-substitution. In addition, the gait monitoring experiment further demonstrated the application potential of PVDF-HFP/HOF nanofibers as a high-performance tribo-sensor. This work demonstrates a structure–property-guided approach to designing engineered fluorine-functionalized HOFs as tunable nanofillers, offering new insights into the development of high-performance triboelectric materials for next-generation electronics.