Study of electrical frequency response through the metal-insulator transition in highly conducting polymers

Based on a random resistor network (RRN), we study the electrical frequency response, including the unusual frequency dependent conductivity and multiple zero crossing of the dielectric function of highly conducting polymers. The electronic transport properties can be studied by modeling the system as a chain-linked granular network, with metallic regions randomly distributed in an amorphous host. Taking into account the contributions of coherent and incoherent transport channels, and the percolation effect of conducting polymers in our RRN model, we can well explain the negative value of epsilon and the low-energy structure of conducting polymers. The calculated epsilon(omega) and sigma(omega) reproduce the main features of recent broadband optical experiments. (c) 2006 American Institute of Physics.