Effective temperature for hopping transport in a Gaussian DOS

For hopping transport in disordered materials, the carrier mobility is strongly dependent on the temperature and electric field. For inorganic materials, with an exponential density of states (DOS), it has been shown earlier that both the energy distribution and the mobility of charge carriers can be described by an effective temperature T-eff (T, E) dependent on the magnitude of the electric field E. We attempt to apply the same ideas to hopping transport in organic materials with a Gaussian DOS. Solving numerically the balance equation for the hopping model we show that both the energy distribution and the mobility of charge carriers can be well described by a field-dependent effective temperature. We also show that the concept of the effective temperature is applicable to description of experimental data on the carrier mobility obtained in RRa-P3HT. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.