Long-Lasting, Steady and Enhanced Energy Harvesting by Inserting a Conductive Layer into the Piezoelectric Polymer

Flexibility, higher piezoelectric performance, and long-lasting stability of devices have a great demand in next generation energy technologies. Polyvinylidene fluoride (PVDF) polymer has a greater mechanical flexibility, but it suffers from low piezoelectric performance. Herein, sandwich-structured piezoelectric film (SS-PF) is designed by inserting the conductive poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) layer between two PVDF layers. The SS-PF based flexible piezoelectric energy harvester (f-PEH) generates higher voltage and current of 3.73 times and 4.64 times than the pristine PVDF film type f-PEH. Moreover, the SS-PF based f-PEH shows no degradation in the output voltage confirming the excellent long-lasting stability over 6 months. DFT simulation shows the occurrence of intermolecular forces between the PVDF/PEDOT:PSS interface. The electric field-dependent charges alignment in PEDOT:PSS may induce the charge accumulation at the PSS-PVDF interface and charge depletion at the PEDOT-PVDF interface leading to the change in orientation of molecular structure in PVDF. Next, the SS-PF based f-PEH is tested for a vibration sensor to monitor the vibrations of curvy pipes and machines, and its output voltages are comparable with the commercial PVDF vibration sensor to confirm the real-time use. The results present a novel design strategy, indicating a new direction for investigating piezo-polymer-based f-PEH.