Dye-sensitized solar cell utilizing organic dyads containing triarylene conjugates

A series of organic dipolar compounds containing a donor (D), a bridge (B), and an acceptor (A), forming a D-B-A type of dyads, were synthesized by convenient methods and were utilized successfully on dye-sensitized solar cells. The central bridges were made of three linearly connected arylene groups, i.e., phenylenes or thiophenylenes. The donor groups were aromatic amines, i.e., either a diphenylamine or a naphthylphenylamine group. The acceptor group was a cyanoacrylic acid, which can be anchored onto the surface of TiO₂ in a photovoltaic device. These devices performed remarkably well, with a typical quantum efficiency of 5-7%, and optimal incident photon to current conversion efficiency (IPCE) exceeding 80%. The devices made with a naphthylphenylamine donor group performed slightly better than those made with a diphenylamine donor group. Compounds containing a phenylene-thiophenylene-phenylene bridge group performed better than those with other kinds of triarylene linkages. Their photochemical behaviors were analyzed by using time-dependent density functional theory (TDDFT) models with the B3LYP functional.