PVDF energy-harvesting devices: Film preparation, electric poling, energy-harvesting efficiency

Poly(vinylidene fluoride) (PVDF) has been recently recognized as an attractive candidate for energy-conversion applications that are fabricated on its piezo- and pyroelectric activities. In this work, Commercial poly(vinylidene fluoride) (PVDF) films are uniaxially stretched with varying rates at 110 °C in order to endow PVDF piezo- and pyroelectric mainly via crystalline-phase transition from nonpolar α to polar β that are identified by infrared (IR) spectroscopy and X-ray diffraction (XRD). The fast stretching promotes the α-to-β phase transition and the quite high β-phase fraction in films resultantly. Additionally, fast stretching benefits to producing a slightly increase of γ phase. Sufficient high electric field applied during poling results in α-to-β phase transition according to the XRD observations. The quantified evaluation on XRD data illustrates that the poling accounts for size-increase and better chain-packing of the β-phase crystallites. The energy-conversion performance of the stretched films that were impacted by water drops as well its relation to the piezoelectric-voltage activity was evaluated by measuring the peak-voltage outputs.