Investigation of the Structure and Piezoelectricity of Poly(vinylidene fluoride-trifluroethylene) Copolymer Doped with Different Dyes

The structure and piezoelectricity of poly(vinylidene fluoride-trifluroethylene) copolymer doped with crystal violet (CV), Coumarin 2 (C2), and N,N-Dimethyl-4- nitro-4-stilbenamine (DANS) were investigated by several techniques. H-and J-aggregates are formed in the CV and C2 doped copolymer, respectively, while DANS doped copolymer showed lamella structure. Moreover, the application of pressure-induced crystalline phase in the CV doped copolymer and TSDC measurements revealed that the ferroelectric to paraelectric transition peak has taken place in the C2 and DANS doped copolymer. Kohlrausch-Williams-Watts stretched function was applied to estimate the relaxation time of the piezoelectric current. The pyroelectricity is found to be dipole-moment-dependent.