Doping level influence on the ferroelectric phase transition in a vinylidene fluoride-trifluoroethylene copolymer

Vinylidene fluoride-trifluoroethylene copolymer films containing the polar dopant rhodamine 6G in different concentrations (from 0 to 1.5 wt %) were s tudied by low-frequency (20 Hz-20 kHz) dielectric spectroscopy over a wide temperature range including the ferroelectric phase transition. A conclusio n was drawn that the dopant is primarily incorporated in the amorphous phas e of the polymer; the pattern of the obtained Cole-Cole plots indicates a s ignificant influence of the through conductance on the low-frequency dielec tric spectra of doped copolymer samples. As the amount of dopant increases, the most probable relaxation time increases, which may be due either to th e emergence of macrodipoles produced from rhodamine 6G molecules and the co polymer or to an increase in their size.