Manipulating functional groups between polyvinylidene difluoride and nanoparticles for high-performance triboelectric nanogenerator

Interface functional groups play an essential role in regulating the electrical properties of bulk materials. In this work, we designed a novel strategy to explore a new way to enhance triboelectric performance by regulating the functional groups between nano-fillers and polymer matrix without obvious changes in the dielectric constant. The silica nanoparticles (SNPs) modified perfluoro-silane coupling agents (PFSCAs) with different chain lengths were added to the polyvinylidene difluoride to regulate the transferred charge density (TCD) of triboelectric nanogenerators (TENGs). When the doping concentration of perfluorodecyl modified SNPs is 2.25 wt.%, the nanocomposite film based TENG exhibits the maximum TCD of 166 µC/m2 and power density of 3.12 W/m2 which are 6 times and 39 times as big as those of pure polyvinylidene difluoride (PVDF) film. The charge accumulation and decay process show that interface functional groups dominate the performance of TENGs. Then, a Fermi level model is proposed and why the TCD could be regulated by the concentration of nanoparticles in bulk materials is explained. This work provides a new concept for understanding the performance of TENG independent dielectric constant and points out a new direction for enhancing TENG’s performance, since wealthy functional groups with selectivity are applicable.