Temperature, charge carrier density, and electric field dependence of mobilities in disordered conjugated polymers: simulation results

We present the results of simulation studies of the dependence on temperature, charge carrier density, and electric field of the mobility mu in disordered conjugated polymers. The disorder is modeled by a Gaussian density of states (DOS) with width sigma. We base our analysis on an exact numerical solution of the Pauli Master equation. The recently experimentally determined carrier density dependence, ranging from densities typically found in light-emitting diodes (LEDs) up to those found in field-effect transistors (FETs), is fully reproduced. At low temperatures T, we find deviations from the generally accepted mu similar to exp[-const.(sigma kT)(2)] behavior. Our calculations show that the electric field dependence does not play a prominent role at the driving voltages of polymer devices.