A study of the optical and electronic properties of poly (vinylidene fluoride–trifluoroethylene) copolymer thin films

Thin films of poly(vinylidene fluoride–trifluoroethylene) copolymer were prepared by spin casting from methylethylketone solutions onto SiO2, Si, and quartz slides substrates. The films were optically transparent in the 1.5–4.5 eV (830–280 nm) photon energy range and found to be uniform and smooth as determined using near ultraviolet–visible spectrum and atomic force microscopy, respectively. A Cauchy model was used to fit spectroscopic ellipsometry (SE) data to obtain the refractive index in 1.5–4.5 eV (830–280 nm) that was found to decrease for thinner films. SE performed at several sensitive angles of incidence has revealed slight optical anisotropy for films thicker than 120 nm. Annealing in vacuum densified the films as evidenced by an increase in the refractive index and a decrease in the film thickness. Capacitance versus voltage measurements revealed a static dielectric constant of about 7.5.