Current–voltage characteristics of disordered organic layers under space-charge-limited conditions based on the transport level concept

An analytical model for calculating the current–voltage characteristic of disordered organic layers with unipolar conduction is developed for conditions when the injected carrier density is sufficiently high to consider deep state population and the current is space-charge-limited. The mobility is calculated based on the transport level concept. The proposed model, being physically clear, well describes the experimental current–voltage characteristics of polymers in a wide temperature range (except for extreme case of high voltages, where the transport level concept should be modified). Thus, this model simplifies calculation and improves the reliability of the theoretical modeling of carrier transport in organic light-emitting diodes.