Diffusion of FeCl 4− in polyacetylene

Abstract

We present a new experimental method to measure the diffusion coefficients of electroactive dopants in conducting polymers. It is based on the continuous recording of the doping level as a function of time and as a function of temperature. The method is applied to diffusion of FeCl 4 − in (CH) x . The data are interpreted according to a model of cylindrical fibrils which leads to the microscopic diffusion coefficient. We give one of the very first measurements of activation energy for diffusion in a conducting polymer. The results 4 × 10 −18 cm 2 s −1 for the diffusion coefficient at room temperature, and 1.0 ± 0.1 eV for the activation energy suggest that the doping process is controlled by a diffusion mechanism via point defects in the crystalline parts of the polymer.