Asymmetric ferroelectric switching characteristics of ferroelectric poly(vinylidene fluoride-ran-trifluoroethylene) thin films grown on highly-oriented pyrolytic graphite substrates

Ferroelectric poly(vinylidene fluoride-ran-trifluoroethylene)(PVDF-TrFE) thin films were deposited on highly-oriented pyrolytic graphite (HOPG) substrates by spin coating. The PVDF-TrFE thin films on HOPG substrates exhibited good ferroelectric properties, with a remnant polarization of 10.2 μC/cm2 (2Pr ∼20.4 μC/cm2) and a coercive electric field of approximately 1.0 MV/cm. A Pt/PVDF-TrFE/HOPG capacitor had an asymmetric ferroelectric hysteresis loop and asymmetric switching speeds. The fast switching speed of a Pt/PVDF-TrFE/Pt capacitor from downward polarization to upward polarization supported the conclusion that HOPG or graphene electrodes provided fast polarization switching when used as one electrode of a ferroelectric PVDF-TrFE capacitor.