Temperature dependence of conductivity of Polyaniline-emeraldine salt in the terahertz region

The terahertz conductivity of Polyaniline-emeraldine salt (PAni-ES) was determined using the terahertz time-domain spectroscopy (THz-TDS). The THz time-domain signals of the reference and the pellet sample were gathered at different temperatures. Results show that the absorption of the sample increases with increasing temperature. The frequency-dependent bevahiour of conductivity was described by the Mott-Davis model. The parameter S in the model was very close to unity suggesting low protonation of the sample. The increase of conductivity with temperature implies thermally-assisted hopping transition. There was a weak dependence of conductivity with temperature at higher frequencies than low frequencies. The conductivity, when scaled, yielded a single curve in the frequency- and temperature-scaled plot. This is a characteristic of fractal-like hopping process shown also in other disordered materials.