Flexible PVDF based piezoelectric nanogenerators

Confronting the depletion of fossil energy and the pollution of chemical batteries, together with the rapid development of various portable electronic devices and the Internet of Things (IoT), there is an urgent requirement to develop high-performance, lightweight, and sustainable energy conversion and power supply devices. Currently, the flexible piezoelectric nanogenerator is a favourable candidate, which can be integrated with personal electronics and wireless sensors to realize sustainable energy for working with long time due to their excellent mechanical properties, good environmental adaptability and outstanding energy harvesting performance. Poly(vinylidene fluoride) (PVDF) and its copolymers, as the most flexible piezoelectric polymer materials, have been widely concerned and become the research hotspot because of their excellent flexibility, strength, easy processing and low cost. To date, significant progress has been made for PVDF based nanogenerators considering improving the output performance to meet the requirement of adapting to complex vibration environments (in vivo or in vitro). Hence, a critical review is presented to systematically summary the recent advance of flexible PVDF based piezoelectric nanogenerators in the aspects of incorporating various nanofillers, structural design, optimizing fabrication techniques and energy harvesting application. Finally, some existing challenges and future perspectives are outlined and discussed to facilitate the development of flexible piezoelectric PVDF based nanogenerators. It is hoped that this review can help researchers to gain a better overall understanding of this field and push forward it to a new stage.