Novel soluble regioregular homopolymer and copolymers incorporating 3,3′-dibutylsulfanyl-2,2′-bithiophene

Homopolymer of the symmetrical 3,3′-dibutylsulfanyl-2,2′-bithiophene (DBSBT) and copolymer of DBSBT with thiophene or bithiophene were prepared by nickel-catalyzed Grignard cross-coupling polymerization. These new solvent-processible regioregular copolymers have UV absorption maxima at about 500 nm in deposited film with a bandgap of 1.7–1.8 eV. They were readily doped by iodine and FeCl3 to an electrical conductivity of 10−3–10−2 S cm−1. The polymers were characterized by FT-IR, NMR, X-ray photoelectron spectroscopy (XPS) spectra and cyclic voltammetry.