Photo-induced effect in conducting polymer solution and interaction of conjugated chain with solvent and solute molecules

Conducting polymers such as polythiophene, polypyrrole, poly(p-phenylene), and poly(p-phenylene vinylene) substituted with long side chain which are soluble in common solvents have been studied. These conducting polymer solutions exhibited unique properties such as solvatochromism and photo-induced effects. On the other hand, cross-linked conducting polymer is nonsoluble, but it exhibits unique gel characteristics such as gel chromism and enhanced conductivity associated with volume instability. These characteristics are discussed in terms of the unique conformation of the polymer main chain in the solvent interaction of the conjugated main chain with solvent molecules, and photoinduced charge transfer.