Thermally stimulated current and electrical conduction characteristics in polychlorophenylacetylene

Thermally stimulated current (TSC) and electrical conduction characteristics of polychlorophenylacetylene (PCPA) film have been measured over wide ranges of temperature and electric fields. The experimental results of TSC show that the peak at the high-temperature region seems to be due to microbrownian motion of the PCPA backbone chain with continuous relaxation times, but the peaks at the low-temperature region are considered to originate from the depolarization of locally oriented dipole groups with a single relaxation time in the PCPA molecule. Three types of electrical conduction mechanisms were deduced depending on the region of the electric field. At low electric fields (less than or equal to 25 MV/m), the ohmic current-voltage characteristic is observed due to the relaxation of dipole groups coupling with the motions of the PCPA backbone chain. However, at the middle electric fields (less than or equal to 95 MV/m), it becomes nonlinear and the predominant conduction mechanism is interpreted to be controlled by the Sehottky effect. At electric fields higher than 90 MV/m, the conduction may be due to the injection of carriers from the electrode and impact ionization.