Comparative study of the exponential-trap-based and the mobility-based space-charge-limited current models for organic diode modeling

Current model is presented for the forward-biased organic diodes. Generally, the diode current consists of two parts: the space-charge-limited current in high-voltage regime and the Ohmic current in low-voltage regime. The two classical space-charge-limited current models, i.e., the exponential-trap-based model and the mobility-based model, are analyzed. Their similarity and difference are clarified: they are similar in the form of the Meyer–Neldel rule, but different in the diode thickness. Comparing their calculated results with the available experimental data at different thicknesses, it is found that, the exponential-trap-based model is suitable, and the mobility-based model shows limitation. Moreover, the Ohmic current model is presented considering the temperature and thickness dependence. Combining the exponential-trap-based space-charge-limited current model with the Ohmic current model, the diode current model is achieved. The model is analytical and suitable for circuit simulation, and is verified by the available experimental data at different temperatures and thicknesses.