Dielectric relaxation in camphorsulfonic acid-doped polyaniline thin film

Abstract

Impedance spectroscopy and dc techniques were employed in order to investigate the relaxation mechanisms in drop casting film of camphorsulfonic acid-doped polyaniline. Both dc and ac conductivity measurements were performed between 298 K and 435 K. Based on the existing theories of ac conduction, it has been concluded that free band conduction is dominant mechanism in the sample. The impedance spectra of the sample displayed an electrode response at low frequency and a single high frequency semicircular arcs in the complex plane plot at all temperatures, with their centres lying below the real axis at a particular angle of depression indicating the distribution of relaxation times. It was found that both the real and imaginary parts of the complex dielectric function showed a saturation at higher frequencies and a strong dispersion at lower frequencies. The overall dielectric properties were mainly dominated by a Maxwell-Wagner type of relaxation with grains and the grain boundary.