Induced Piezoelectricity in Poly(vinylidene fluoride) Hybrid as Efficient Energy Harvester

Abstract

Poly(vinylidene fluoride) (PVDF) nanohybrid with organically modified two-dimensional nanoclay, prepared through solution route, has been fabricated as the energy harvester. The nanoclay induces piezoelectric phase in PVDF arising from epitaxial crystallization over the nanoclay layers. Further enhancement of piezoelectricity has been made by stretching the film at high temperature showing ∼80% β-phase along with some γ-phase in nanohybrid. Orientation of the nanofiller along the force field creates the nanohybrid tougher and suitable for device fabrication. Mapping of piezo-domain has been constructed through piezo force microscopy indicating 100 nm dimension of the electroactive phase in stretched nanohybrid as opposed to almost zero size in pure PVDF. Structural alteration has also been confirmed through spectroscopic and thermal measurements. Morphology also supports the formation of β-phase in presence of nanoparticle (spherulite to needle like morphology). The piezoelectric coefficient shows a significant increase after processing due to greater piezoelectric phase and the fabrication of unimorph has been made using high piezoelectric coefficient material showing higher peak to peak voltage generation of 2.5 V with much longer response time (6 ms) in stretched nanohybrid under an impulse load. Finally, the voltage and current output from the devices are measured under varying load and highest power density value of 25 μW/cm3 is obtained for stretched nanohybrid, more than sufficient to operate a miniature self-powering device. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim