Hole transport in poly(p-phenylene vinylene)-based light-emitting diodes revisited

Understanding of the charge transport properties is of great importance for the operation and the efficiency of polymer based light-emitting diodes (LEDs). We investigate the charge transport in hole-only diodes based on poly(p-phenylene vinylene) (PPV) as function of temperature T, charge carrier density p and electric field E. At low voltages the hole mobility is independent on the electric field and charge carrier density. At high voltages both the charge-carrier density and electric-field dependence of the mobility have to be taken into account to describe the hole transport in polymer LEDs.