Conductivity of oriented polyacetylene doped by alkali metals: Time, temperature, and pressure dependence.

Abstract

We report the time, temperature, and pressure dependence of conductivity of oriented polyacetylene doped by alkali metals. The in situ conductivity data show that the doping process, by intercalation, is dependent on the size and structural ordering of the ions in the polyacetylene matrix. Steplike features in the in situ conductivity measurements show the presence of doping-induced staging transitions. The temperature dependence of conductivity follows a power law, indicating that the system is at the critical regime of the metal-insulator transition, for which the Fermi level is near the mobility edge. We find a weaker temperature dependence for potassium-doped polyacetylene as compared to sodium-doped polyacetylene. The increase of conductivity at high pressures as well as its weaker temperature dependence shows the important role of the interchain interactions for improving the conductivity of alkali-metal-doped oriented polyacetylene.