TRANSPORT ENERGY FOR HOPPING IN A GAUSSIAN DENSITY-OF-STATES DISTRIBUTION

The energy, epsilon(t), most frequently visited by charge carriers migrating via hopping within a Gaussian density of states distribution has been simulated employing Monte Carlo techniques. In the case of weak intersite coupling relevant for organic systems, it is found that (i) there is a broad distribution of epsilon(t) values and (ii) its maximum decreases with decreasing temperature in qualitative agreement with the concept of variable-range hopping. More detailed data analysis indicates, however, that the epsilon(t)(T) dependence is not caused by the involvement of long-distance jumps but by oscillations among energetically dose-by sites and indicates that epsilon(t) is a statistical quantity rather than a microscopic transport energy.