Reduction and transition in thermal activation for charge transport through electrolyte-gated polythiophene thin films with high hole densities

Abstract

We investigate the activation energy for electrical charge transport through a polythiophene thin film. The results are particularly obtained under high hole density (5.9 x 10(20) holes/cm(3)) through electrolyte-gating and are compared with previous results attained from the same polymer film but with low induced carrier densities. Comparative analyses show that introducing high hole densities into the polymer results in (i) suppression of the transport activation energy and (ii) reduction of the temperature that yields transition in the activation energy. These results are explained based on the formation of bipolaron states, which are generated at such high hole densities. (C) 2013 AIP Publishing LLC.