TRANSPORT IN MOLECULARLY DOPED POLYMERS - DISPERSIVE OR NONDISPERSIVE

Charge transport in molecularly doped polymers occurs by hopping among random sites. Anomalous diffusion is revealed in the ratio of diffusi on constant to mobility which greatly exceeds the Einstein relation. W e describe a method which allows the analysis of experimental current transients to determine the distribution of arrival times at the colle cting electrode and fmd that the distribution of inverse arrival times closely approximates a Gaussian, with a relative width approaching un ity. Theoretically we show that similar behavior can arise when either or both distributions of waiting times and hopping distances are wide relative to their means. It is not necessary that the transport be di spersive in the sense that the mean waiting time be infinite, as it is , for example, with a power law distribution of waiting times.