Electrical conduction mechanism in solution grown thin polyvinylchloride (PVC) films

Abstract

The electrical transport behaviour of thin polyvinylchloride (PVC) films deposited by the solution growth technique has been investigated. The current transport in PVC films of 2500 Å thickness at temperatures below 250 K is ascribed to hopping mechanisms. The weak temperature dependence of the conductivity is attributed to interchain hopping, whereas the strong temperature dependence is attributed to the trap hopping process. The conductivity of PVC films is increased on doping with iodine. This is interpreted on the basis of the formation of charge transfer complexes in the film. The activation energy for conduction increases from 0.7 to 1.22 eV at 315 K and decreases from 2.2 to 0.8 eV at 375 K on doping PVC films with iodine (0.7 g of iodine per 100 ml PVC solution). At high (≧5 × 10⁴ V cm^-1) fields and at higher (≧350 K) temperatures, the observed conduction behaviour can be described by the Schottky emission mechanism. The height of the Schottky barrier is found to depend on the type of the metal electrode and the direction of the current. The barrier height decreases with increasing iodine concentration in the PVC films.