Gaussian disorder model for high carrier densities: Theoretical aspects and application to experiments

It is shown that the precondition for the common Boltzmann approximation usually utilized in many hopping models for organic semiconductors is easily violated in most experiments. A vivid hopping model which takes the Fermi distribution into account is presented to describe the equilibrium transport in organic semiconductors also for higher carrier densities. The description is based on the Miller-Abraham model for hopping in a disordered material and utilizes the so-called "transport energy concept." Deviations from the common low-density approximation are discussed. The formalism is applied to recently published transport data of doped organic semiconductors.