On the inverse field dependence of conductivity in disordered organic materials

Recently the change in temperature dependence of conductivity observed in polymer memory device prepared from polythiophene, has been attributed to a field-induced transition from a charge-injection-limited current to a trap controlled current. Under a high electrical field, the conductivity becomes independent on temperature and depends exponentially on the inverse of the applied field. In this paper we present a theoretical interpretation of this behavior in the framework of hopping mechanism, where the physical feature is the field effect on the tunneling probability.