Circuital Modelling of Polarization and Depolarization Currents in Polymeric Materials under Low Electric Fields

This paper proposes a circuital model that describes polarization and depolarization currents observed in thin samples of polymeric materials under the application of an average electric field up to 30 kV/mm. The model employs the least possible number of parameters to fit the experimental measurements. A single carrier with negative charge is considered. The polarization curves are modelled by a power law to account for transport assisted by shallow traps. A model for the deep traps with a Gaussian distribution of the density of states is describes the depolarization curves. Experimental measurements made on various materials with different charging and discharging times suggest that a portion of the deep traps is filled within few seconds, while the time needed to release the trapped charges is in the order of several hours. The agreement between experimental and simulated currents confirms the validity of the proposed model, that can be seen as a generalization of the extended Debye model.