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

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 similar to 80% beta-phase along with some gamma-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 spectro-scopic and thermal measurements. Morphology also supports the formation of beta-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 mu W/cm(3) is obtained for stretched nanohybrid, more than sufficient to operate a miniature self-powering device.