Hydroxylated BiFeO3 as efficient fillers in poly(vinylidene fluoride) for flexible dielectric, ferroelectric, energy storage and mechanical energy harvesting application

Abstract

Here we report the effect of surface hydroxylation of BiFeO₃ fillers on the dielectric, ferroelectric, energy storage and mechanical energy harvesting performance of poly(vinylidene fluoride). Surface hydroxylation helped to improve the interfacial interaction between the filler and PVDF matrix by introducing a strong hydrogen bonding between the –OH group of the hydroxylated BiFeO₃ filler surface and the –CF₂ dipole of PVDF in place of electrostatic interfacial interaction between non-hydroxylated BiFeO₃ and the –CH₂ dipole of PVDF. The amount of polar phase increased to around 91% for a 7 wt% hydroxylated BiFeO₃ loaded PVDF film (7BFOH) by this new type of interfacial interaction. The dielectric, ferroelectric, energy storage and mechanical energy harvesting performance of the PVDF based composite films also improved by the above said technique. Upon repeated human finger tapping, the 7BFOH film delivered ∼18 V output peak to peak open circuit ac voltage (V_OC). After rectification, the V_OC of the 7BFOH film was able to charge a 10 μF capacitor up to ∼3 V which was able to light up some LEDs (connected in parallel) together instantaneously, which proved the real life applicability of the composite films in low power consuming self-powered electronic devices.