Charge-transfer doping of poly(3-alkyl-2,2′-bithiophene)

Spin-cast films of the title polymer, a highly ordered, flexible, and soluble polythiophene, can be doped with solutions of dichlorodicyanoquinone (DDQ) to produce a highly conducting material. The doped films of the polybithiophene exhibit strong bipolaronic absorptions, consistent with the formation of charge-transfer polymers. Weaker dopants, e. g., benzoquinone, are not effective. The use of organic dopants of this type provides a superior method for production of stable conductive materials. Spectroscopic and thin-film x-ray diffraction data support a charge-transfer mechanism.