DC electrical conductivity of carbon black polymer composites at low temperatures

The understanding of the charge transport mechanism of the conducting polymers and their composites is important for the successful fabrication of semiconductor devices. In this work, the DC electrical conductivity of carbon black particles in a polystyrene matrix, in the temperature range of 80 to 250 K is examined, for concentrations below the critical percolation concentration. We show that three-dimensional variable range hopping is observed, that is, the temperature behavior of the DC conductivity can be expressed by sigma = sigma(0)exp [-(T-0/T)(1/4)]. From the hopping parameter we obtained the mean hopping distance, the density of active centers and the energy associated with it. (C) 2011 Elsevier B.V. All rights reserved.