Effects of an external electric field on the ferroelectric-paraelectric phase transition in polyvinylidene fluoride-trifluoroethylene copolymer Langmuir–Blodgett films

Abstract

Effects of an external electric field on the ferroelectric-paraelectric phase transition in polyvinylidene fluoride-trifluoroethylene copolymer Langmuir-Blodgett films X-ray diffraction and capacitance measurements have been employed to study the structural and dielectric behavior of the ferroelectric-paraelectric phase transition under the influence of a large external electric field. The samples under study are ultrathin ͑15-100 nm͒ Langmuir-Blodgett films of a copolymer of vinylidene fluoride ͑70%͒ with trifluoroethylene ͑30%͒ deposited on aluminum-coated silicon. In situ -2 x-ray diffraction was used to measure the change in interlayer spacing perpendicular to the film surface, corresponding to the ͑110͒ direction and indicating that the polymer chains along ͑001͒ lie predominantly in the plane, while capacitance measurements were used to monitor the behavior of the dielectric constant of the film. Application of a large electric field, up to 265 MV/ m, raises the phase transition temperature and can convert the nonpolar trans-gauche paraelectric phase to the polar all-trans ferroelectric phase in a reversible manner.

Influence of an External Field on the First Order Ferroelectric Phase Transition

“…The simulation results are qualitatively in very good accordance to the curves given in standard textbooks, e. g. [5,6]. In [7] Poulsen et al observe the phase transition using the temperature dependence of the electrical susceptibility. They find that T C is shifted towards higher values when an external field is applied.…”

Understanding the effect of ferroelectric polarization on power conversion efficiency of organic photovoltaic devices

“…The LB-deposited 2 monolayer (ML) P(VDFTrFE) films with an average thickness of 3.4 nm were annealed for 30 minutes at 135 C to optimize their crystallinity. [16][17][18] The P(VDF-TrFE) films formed by spin coating with an average thickness of 3.2 nm were annealed at a lower temperature of 90 C for 10 min as described in ref.…”

Change from second order to first order ferroelectric phase transition by polarization induced strain

“…5) as well as the thermal hysteresis ( Fig. 6) have been observed by M. Poulsen et al [8] using polyvinylidene fluoridetrifluoroethylene copolymer (P(VDF-TrFE)).…”