Electrical and optical properties of doped helical polyacetylene graphite films in terahertz frequency range

We report on electrical and optical characteristics such as power absorption, index of refraction, and conductivity of new form of the model conjugated polymer–polyacetylene (PA)–helical PA graphite films (h-PA) in the 0.1–2.5 THz spectral range. The results were obtained using the transmission THz time-domain spectroscopy. The frequency dependencies of the electrical and optical characteristics can be reasonably well fitted by the Drude model, which gives a plasma frequency of about ∼124 THz and a charge carrier scattering time ∼30 fs, which is less by an order of magnitude than that of crystalline materials. The obtained results demonstrate that doped h-PA graphite films retain metallic behavior in the THz spectral range even at ambient conditions contrary to conventional doped PA films.