DIPOLE TRAP MODEL AND CONCENTRATION-DEPENDENCE OF CHARGE-CARRIER MOBILITY IN DISORDERED ORGANIC MATRICES

Using a dipole trap model we propose an explanation of the experimentally observed drastic decrease of the carrier drift mobility with the increase of average distance between transport sites. We demonstrate that in general case mobility activation energy depends on this distance. In addition we demonstrate that observation of the decreasing dependence of activation energy on average intersite distance must be a very rare event, in full agreement with experimental data. We show that the absolute value of the mobility, calculated using our approach, is in good agreement with the experimental one. We demonstrate that it is natural to expect the approximate independence of the activation energy on the average intersite distance for dopants with high dipole moments. Such correlation was really observed in experiments.