Low-Bandgap Benzodifuranone-Based Polymers

pi-Conjugated monomers and polymers containing benzodifuranone units in the main chain were prepared. Polymers were obtained using palladium-catalyzed Suzuki and Stifle polycondensation reactions of dibromo-substituted benzodifuranone derivatives with either dihexylfluorene diboronester or bis(trimethylstannyl)thiophene. The optical and electronic properties were investigated using UV/vis absorption spectroscopy and cyclic voltammetry. It was found that the polymers show very broad absorption bands with a high extinction coefficient up to 32500 L mol(-1) cm(-1). The polymers also show reversible redox behavior, giving small HOMO-LUMO gaps up to 1.30 eV with strong donor-acceptor character.