Synthesis of donor–acceptor type new organosilicon polymers and their applications to dye-sensitized solar cells

Donor–acceptor type new organosilicon polymers that consisted of bithiophene unit as the donor and benzochalcogenadiazole or pyridine as the acceptor were synthesized by the Stille cross coupling reactions of bis(iodothienyl)benzochalcogenadiazoles or bis(bromothienyl)pyridine with 1,2-bis(trimethylstannylthienyl)disilane. The photoreactions of these polymers with TiO2 electrodes led to the polymer-modified electrodes by the formation of Si–O–Ti linkages. The pyridine-containing polymer pT4Py could be attached to the TiO2 surface also under the dark conditions by N–Ti coordination. The polymer-modified TiO2 were applied to dye sensitized solar cells and the highest power conversion efficiency of 0.40% was obtained with the TiO2 electrode photochemically-modified by pT4Py.