Effects of biomimetic cross-sectional morphology on the piezoelectric properties of BaTiO₃ nanorods-contained PVDF fibers

In this study, the effects of the morphology of components on the performance of a piezoelectric nanogenerator were investigated. Polyvinylidene fluoride (PVDF) fibers with biomimetic cross-sectional morphologies inspired by plants were fabricated by integrating melt spinning, winding, and corona poling. The cross-sectional morphology of the PVDF fiber significantly influenced the piezoelectric performance because of differences in the exterior surface area and contact volume, which are important in the production of β-phase PVDF and crystallinity. The daffodil flower-shaped PVDF fiber exhibited the best piezoelectric performance among the PVDF fibers with various biomimetic cross-sectional morphologies (i.e., daffodil flower, radish flower, papyrus stem, and stalk grain stem) possessing different active areas for piezoelectricity generation. Its open-circuit voltage of 36.05 V and short-circuit current of 3.126 μA are attributable to its highest exterior surface area and contact volume, which maximize the active area (deformation area) for piezoelectricity generation. The effect of the morphology (nanoparticles and nanorods) of BaTiO₃, which is another component of the piezoelectric nanogenerator, was also investigated using BaTiO₃-contained PVDF fibers involving the daffodil flower-like cross-sectional morphology, namely, the PVDF-daffodil/BaTiO₃ nanoparticle (NP) and PVDF-daffodil/BaTiO₃ nanorod (NR). Compared with nanoparticles, the rod morphology more efficiently promoted asymmetry in the fiber during fabrication. The PVDF-daffodil/BaTiO₃ NR produced an excellent open-circuit voltage of 62 V and a maximum power of 91 μW from human motion. This study provides new insights for the practical mass production and utilization of high-performance piezoelectric nanogenerators.