Influence of bipolaron density on the transport properties of thermalized organic conductors



We investigate the influence of the number of bipolarons and temperature on the transport mechanism of doped conducting polymer under the action of an electric field. To do so, a version of the one-dimensional Su-Schrieffer-Heeger model, modified to include thermal effects, impurities, and an external electric field, is used. It is observed that the interaction between the bipolarons is of fundamental importance to the correct description of the system dynamics. For higher densities, the overall systems mobility tends to increase. This increase is found to arise from the two different, yet correlated, processes of carrier untrapping and velocity gain. Temperature is also observed to play a major role in increasing the mobility of the charge carriers. Hence, for the first time in the literature, it is possible to estimate bipolaron responses to these stimuli, in agreement with experimental evidence. © 2013 Wiley Periodicals, Inc.