Tailored Poly(vinylidene fluoride--trifluoroethylene) Crystal Orientation for a Triboelectric Nanogenerator through Epitaxial Growth on a Chitin Nanofiber Film.

Tailoring the crystal orientation of poly(vinylidene fluoride--trifluoroethylene) (PVDF-TrFE) has attracted widespread interest because of its effects on the ferroelectric properties required for various electronic devices. In this study, we investigated the epitaxial growth of PVDF-TrFE on a chitin film for developing triboelectric nanogenerators (TENGs). The crystallographic match between the chitin and PVDF-TrFE enables the development of the intended crystal orientation, with the PVDF-TrFE polarization axis aligned perpendicular to the substrate. In addition, the epitaxially grown PVDF-TrFE on chitin not only enhances the performance of the TENG but also increases the stability of the hygroscopic chitin film against water. The corresponding TENG exhibits a significantly higher output current compared to that of a nonepitaxial PVDF-TrFE/chitin film. Furthermore, the triboelectric sensors based on epitaxial PVDF-TrFE/chitin films allow the monitoring of subtle pressures, suggesting that tailoring the crystal orientation of PVDF-TrFE is a promising approach for developing high-performance TENGs.