Dynamic hysteresis scaling behavior in polyvinylidene fluoride-trifluoroethylene ferroelectric copolymer thin films

Abstract

In this paper, we investigated the dependence of dynamic hysteresis on the electric field amplitude E0 and the frequency f in organic ferroelectric copolymer polyvinylidene fluoride-trifluoroethylene [P(VDF-TrFE)] thin films prepared by a spin-coating method on fluorine-doped tin oxide conductive glass. Three stages can be observed of the hysteresis area vs the field strength E0. In stage I of low E0 values, the area ⟨A⟩ dependent on E0 follows the law of ⟨A⟩∝E01.92795, whereas the diverse distribution of the area ⟨A⟩ with frequency f is found. In stage II of the intermediate E0 values, ⟨A⟩∝E0β is not applicable owing to collective contributions between 180° domain and chiral domain, while a relation of ⟨A⟩∝f−0.18636 can be deduced, a fascinating characteristic distinguishing from the nonlinear relations of the inorganics in this section. In stage III of high E0 values, the scaling law is ⟨A⟩∝f0.08447E00.49394 where the chiral domain is active. The positive β in the law of ⟨A⟩∝fαE0β illustrates that a growing number of chiral domains in P(VDF-TrFE) can keep pace with the variation of E0. Especially, the negative α in the transition zone, resembling some inorganics under low electric fields, probably indicates 180° domain reversal failing to follow with the alternating velocity of the increasing periodic electric field.