Optimized output of piezoelectric energy harvesters with coaxial PVDF/PAN/CNT composite fibers

While flexible self-powered electronic devices have shown promising prospects for development, substantial challenges remain in enhancing their power output and structural integrity. This study investigates the fabrication of organic piezoelectric nanofibers with a coaxial structure, achieved by electrospinning polyvinylidene fluoride (PVDF) and polyacrylonitrile (PAN), incorporating carbon nanotubes (CNTs). Due to the viscosity differences between PVDF and PAN, the electrospinning process results in a coaxial morphology. The interactions between the dipoles and hydrogen bonds of PAN and PVDF promote the formation of a piezoelectric active phase. The introduction of CNTs as nucleating agents enhances the β-phase content of PVDF and promotes the planar zigzag conformation of PAN. After hot pressing, the resulting terpolymer composite fiber films, are used to construct piezoelectric energy harvesting devices (PEHs). The P/P/C-0.2 PEH, containing 0.20   wt% CNT and 20   wt% PAN, achieves a high open-circuit voltage (V OC ) of approximately 13.7   V and a maximum power density of 0.75 μW/cm 2 in bend-release mode. This device exhibits a stable voltage output over 10,000 cycles, maintaining an output voltage of 7.5   V at 75 °C. Additionally, the PEH effectively captures mechanical energy from human movement. This research presents a promising approach to enhancing the piezoelectric output of flexible piezoelectric devices.