Piezoelectric Nanogenerators Based on Helical Carbon Materials and Polyvinyledenedifluoride–Trifluoroethylene Hybrids with Enhanced Energy-Harvesting Performance

The geometry of piezoelectric materials has a great impact on the output performance of piezoelectric nanogenerators (PNGs), a promising candidate for providing electricity in wireless systems. The nanohelix has been considered as a hopeful nanostructure for PNGs due to the geometrical stress confinement effect and has been demonstrated by finite element analysis. Herein, helical nanobelts of graphene/poly(vinylidenefluoride-co-trifluoroethylene) (PVDF–TrFE) and multiwalled carbon nanotube (MWCNT)/PVDF–TrFE hybrids are prepared using a direct-write technique. The PNGs based on these helical nanobelts are fabricated and effectively harness mechanical energy to generate electricity. The output voltages of the PNGs based on the pure helical PVDF–TrFE, MWCNT (0.03 wt%)/PVDF–TrFE, and graphene (0.03 wt%)/PVDF–TrFE nanobelts are recorded. The average outputs of the three kinds of PVDF helical nanobelts are approximately 10.3, 11.9, and 20.7 mV, respectively. The maximum of output voltage of 35 mV is achieved using the graphene (0.005 wt%)/PVDF–TrFE nanobelts. Geometrical stress confinement is identified as a mechanism responsible for high piezoelectricity in nanostructures, rendering the helical nanogenerators potentially advantageous for efficient energy harvesting.