Improved charge stability in PTFE coatings for PDMS ferroelectrets

Charge dissipation in previous Polydimethylsiloxane (PDMS) ferroelectrets was observed and the piezoelectric coefficient d(33) of most samples drop to below 10 pC/N in one month after charging. This issue limits its long-term energy harvesting performance. This paper presents an approach to coat the PDMS with Polytetrafluoroethylene (PTFE) to enhance the surface charge stability of the ferroelectret. After coating a thin PTFE film in the void surfaces of PDMS ferroelectret, the piezoelectric coefficient d(33) obtained remained at 80 pC/N after 6 months.