Low-dimensional variable range hopping in conducting polymers

Highly conducting polymers such as polyaniline and polypyrrole in a dielectrical stare have unusually strong temperature of dependence of dynamic conductivity. We argue that this strong temperature dependence is due to the low dimensionality of charge transport in the polymers. The hopping network is formed by fast one-dimensional diffusion along the chains and rare interchain hops. Depending on the chain morphology the network is modeled by a quasi-one-dimensional system of randomly linked chains or by a quasi-one-dimensional chain fractal with dimensionality 1 + s, where s << 1. We point out the experimental data for dielectric constant and ac-conductivity that supports these two models. (C) 2001 Elsevier Science B.V. All rights reserved.