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 experimenta lly observed drastic decrease of the carrier drift mobility with the i ncrease of average distance between transport sites. We demonstrate th at in general case mobility activation energy depends on this distance . In addition we demonstrate that observation of the decreasing depend ence of activation energy on average intersite distance must be a very rare event, in full agreement with experimental data. We show that th e absolute value of the mobility, calculated using our approach, is in good agreement with the experimental one. We demonstrate that it is n atural to expect the approximate independence of the activation energy on the average intersite distance for dopants with high dipole moment s. Such correlation was really observed in experiments.