Lead-Free Compositional Engineering to Induce Polar Phase in Polymeric Piezoelectric Host for Energy Harvesting Devices

Abstract

With the growing demand and environmental concerns regarding applied electronic materials, a shift toward lead-free piezoelectric materials has been seen since the past decade. Polyvinylene difluoride (PVDF) serves as a lead-free and ultralight-weight piezoelectric polymer for flexible self-powered sensors and actuators; however, it suffers from low energy harvesting efficiency (10–12 V maximum output at a typical pressure in the range of 10–20 N/cm2 for pure PVDF) due to the dominance of the nonpolar alpha (α) phase. In this work, we developed a method of using the nonpolar α phase to show the performance of piezoelectric response surpassing the reported PVDF-TrFe (trifluoroethylene-grafted PVDF) by compositional engineering with the help of inorganic fillers. The energy harvesting capability of pure PVDF was increased by almost 180% with the help of filler materials such as barium titanate (BaTiO3 or BTO) at PVDF:BTO = 95:5 wt %. The local piezoelectric coefficient (d33) of these films was increased from 12 to 26 pm/V, which correlates well with structural and energy harvesting device (widely known as a piezoelectric nanogenerator, PENG) studies. Our investigations enable pure PVDF to be used in place of PVDF-TrFe, which is a cost-effective solution for energy harvesting devices.