Power generation by PVDF-TrFE/graphene nanocomposite films

Abstract Poly(vinylidene difluoride)(PVDF) and its copolymers are promising materials to fabricate self-powered devices, while their relatively low power generation capability limits their applications. In this work, graphene was added into poly(vinylidene-trifluoroethylene)(PVDF-TrFE) to prepare excellent piezoelectric composite films by a solution-casting method. The PVDF-TrFE/graphene containing 0.15 wt% graphene generated a calibrated open circuit of 12.43 V, which is 104% higher than that without graphene. Similarly, the harvested power density was increased by 302% (AC circuit) and 359% (DC circuit), respectively. The XRD spectra indicate that the PVDF-TrFE/graphene with an extremely low content of graphene did not work well on the phase formation in the initial crystallization. The crystallinity degree of the untreated films was about 40%. After stretching, the crystallinity degree increased to above 60%, especially for the films containing 0.15 wt% graphene (67%). Hence, stretching was the main factor to increase the crystallinity degree. This study also confirmed that the heat treatment could further improve the crystallinity of the stretched films to some extent.