Thermoelectric power in inhomogeneous metallic polymers

Thermoelectric power (TEP) in well conducting doped polymers is studied within a simple model in which the existence of metallic strands separated by thin potential barriers is assumed. It is shown that if the barriers dominate the dc electrical conductivity σ_dc(T) leading to a variable range hopping (VRH) conduction, they also give rise to a sub‐linear behaviour of TEP vs. temperature. The model predicts an enhanced TEP at high temperatures. It also indicates that due to the barriers the evaluation of Mott's parameters for VRH from the measured σ_dc(T) typically leads to incorrect values for, e.g., the density of states. The calculated TEP vs. temperature is compared with experimental data on heavily doped polyacetylene and polypyrrole.