Efficient energy harvesting enabled by large-area piezoelectric PVDF-based composite film enhanced by carbon nanotubes

Considerable attention has been drawn to the use of flexible piezoelectric energy harvesting devices for powering smart wearable technology. Herein, we employed a melt extrusion casting process to prepare large-area PVDF-based piezoelectric composite films and achieved continuous production. The films were prepared by adding 15 wt% lead zirconate titanate powder modified with a titanium coupling agent (PZT@UP15) and different content of carbon nanotubes (CNTs) exhibiting high conductivity into the PVDF matrix. The addition of CNTs in moderate amounts significantly enhanced the mechanical, dielectric, and piezoelectric properties of the composite films. Remarkably, the composite film containing 0.06 wt% CNTs achieved a d33 value of 28 pC/N, generated an open circuit voltage of 16.85 V, and a maximum power density of 0.46 μW/cm2 in the bending-releasing mode. Furthermore, the film exhibited relatively stable output performance even after 1500 cycles. The enhanced performances of the piezoelectric composite films can be attributed to the factors that the CNTs can effectively promote PVDF polarization by inducing dipole alignment and building an internal electric field, and further improve the piezoelectric performance and the electrostrictive performance. This work shows that the prepared piezoelectric composite film holds great potential as an energy harvesting device to provide power for wearable electronic devices.