Relation between intra-chain conduction and main-chain conformation of conducting polymers in solutions as studied by electric birefringence spectroscopy

Frequency domain electric birefringence spectroscopy has been applied to a typical soluble conducting polymer, poly(3-hexylthiophene), in dilute solutions in order to investigate the isolated single-chain dynamics of conducting polymers. From the results, the intramolecular conduction mechanism in a single conducting polymer chain is revealed without interference from the inter-chain one. The change in hydrodynamic diameter of the polymer chain with varying temperature or solvent species clearly indicates the occurrence of a single-chain conformational transition. Further, it turns out that there exist two kinds of carrier transport process along the polymer chain with different diffusion distances and diffusion constants, which reflect a disorder effect due to conformational defects on the one-dimensional polymer chain. Copyright (C) 1999 Elsevier Science B.V.