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 solut ions in order to investigate the isolated single-chain dynamics of conducti ng 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 w ith varying temperature or solvent species clearly indicates the occurrence of a single-chain conformational transition. Further, it turns out that th ere exist two kinds of carrier transport process along the polymer chain wi th different diffusion distances and diffusion constants, which reflect a d isorder effect due to conformational defects on the one-dimensional polymer chain. (C) 1999 Elsevier Science B.V. All rights reserved.