Low-dimensional variable range hopping in conducting polymers

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