Frequency-dependent activation energy of terahertz conductivity in Polyaniline-Emeraldine Salt

Abstract

The temperature-dependent terahertz (THz) conductivity of Polyaniline Emeraldine Salt was measured using THz time-domain spectroscopy. By using the time-domain signals, simultaneous measurements of amplitude and phase enable the calculation of absorbance and the index of refraction. These give the dielectric constant and, finally, conductivity. The temperature range studied was from 80 K to 290 K. It was found out that the THz conductivity is described by the Mott-Davis model, a phonon-assisted hopping model. This is expressed by a power law. The power is found to be inversely dependent with temperature. There is a possibility of this being related to correlated barrier hopping. Lastly, the activation energies were calculated using Arrhenius equation. The activation energies decrease with increasing frequencies.