Effect of β -Chain Alignment Degree on the Performance of Piezoelectric Nanogenerator Based on Poly(Vinylidene Fluoride) Nanofiber

This work demonstrated the effect of the β -chain alignment degree on piezoelectric nanogenerator (PNG) performance. A simple, safe and low-cost fast-centrifugal spinning technique was used to produce self-poled poly(vinylidene fluoride) (PVDF) nanofiber. PNG based on acetone-prepared PVDF fibers, with high β -chain alignment, generated output open-circuit voltage ( V OC ) and short-circuit current ( I SC ) five times higher than the film counterpart. In addition, the fibers showed a remarkable increase in β -chain alignment degree as the ratio of N,N -dimethylformamide (DMF) solvent increased. The optimum nanofiber with the highest β -chain alignment degree, β -fraction and piezoelectric charge coefficient of 0.93, 91.8% and -120 pC.N − was obtained, respectively. PNG based on the optimum fiber displayed the highest V OC , I SC and power density of 14 V, 1.4 µA and 6.7 µWcm −2 , respectively. This performance is greater than any PNG made from electrospun PVDF fiber. The excellent performance of the fabricated PNGs was strongly related to the high alignment degree of β -chains parallel along the fiber axis. In addition, due to low Young’s modulus (1.63 MPa) of the optimum fibers, the related lead-free PNG is sensitive to small movements and can be used in wearable and implanted medical devices.