Dielectric and Ferroelectric Properties of P(VDF-TrFE) Films with Different Polar Solvents

초록

We investigated the structural, dielectric, and ferroelectric properties of poly(vinylidenefluorideco-trifluoroethylene) [P(VDF-TrFE)] films that were grown using dimethylformamide (DMF) and tetrahydrofuran (THF) polar solvents. The DMF solvent has a large dipole moment with a long bond length and evaporates slowly while the THF solvent has a small dipole moment with a short bond length and evaporates rapidly. Because of these differences, a thin film with a rough surface occurs when using DMF while a thick film with a smooth surface is formed when using THF. Compared to DMF solvent, the ferroelectric polarization is not well saturated and the dielectric constant is quite low for the THF solvent, which is possibly due to the residual paraelectric defects in the P(VDF-TrFE) films. For both solvents, the polarization switching can be explained by using the Kolmogorov-Avrami-Ishibashi (KAI) model with similar switching times. Both solvents enable the P(VDF-TrFE) films to have good retention and fatigue resistance for ferroelectric polarization.

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