TRANSPORT-PROPERTIES OF FECL3-DOPED POLYPYRROLES AT DIFFERENT DOPANT CONCENTRATIONS

The electrical conductivities of FeCl3-doped polypyrrole samples with different dopant concentrations have been measured in the temperature range 25-300 K. Thermoelectric power measurements have been performed on two polypyrrole samples at low doping levels between 50 and 300 K. The variation in DC conductivity can be explained by Mott's variable-range hopping (VRH) model. Fitting with Mott's VRH theory, the conductivity data provide the values of the density N(is-an-element-of(F)) of states at the Fermi level and the hopping distance R. The low value and the sublinear character of the thermoelectric power is consistent with the VRH theory.