Hopping transport in polythiophene versus poly(phenylene vinylene)

We have studied the hopping transport in two FeCl3 doped conjugated polymer s - a poly(phenylene vinylene), PPV, and polythiophene, PTh, derivative. Su rprisingly, the conductivity of PPV is orders of magnitude higher than that of PTh at the same doping level. Analysis of the de conductivity and high frequency (0.03-10 THz) response as a function of temperature, enables us t o account for these differences. While in PTh carriers are strongly localiz ed onto quasi-1D chains, the higher interchain overlap in PPV provides an e ffectively 3D conductive structure. Especially the data above 0.1 THz are v ery illustrative for the almost "metallic" contact between the PPV chains.