Carrier transport in conducting polymers with field dependent trap occupancy

The space charge limited currents J in conducting organic materials often show J∼Vm (where m>2) dependence on voltage V. Two models have been used extensively to understand this behavior. In one model, the mobility μ is assumed to be dependent on electric field F. In the other model, an exponential distribution of traps is assumed and the mobility is taken to be independent of field. In this model the influence of the high electric fields present in organic polymers has not been taken into account. We present a model to calculate the J(V) characteristics for single carrier organic polymers taking into account the change in the occupancy of the traps due to the high electrical fields present in these materials. We show that the field dependent trap occupancy (FDTO) model can effectively explain the current–voltage characteristics reported by several different groups. If the FDTO model is used, it is not necessary to use the two different models mentioned above.