The localization-interaction model for the DC-conductivity of metallic conducting polymers

The low temperature DC-conductivity (σ) of doped conducting polymers on the metallic side of the metal-insulator transition is analyzed with modern localization-interaction theories. The transition from negative to positive temperature coefficient of resistivity, below 20 K, can be explained by the sign change in the interaction coefficient ‘m’ (σ=σ0+mT1/2). Based on experimental data it is shown that the resistivity ratio ρr (ρr=ρ(T≅1 K)/ρ(300 K)) is a controlling factor in determining the sign and magnitude of these effects. It is shown that the coefficient m crosses from negative to positive values at different values of ρr for oriented and non-oriented conducting polymers.