Dye-sensitized solar cells (DSSCs) have been intensively investigated over the past decade. In order to improve the photovoltaic performance of DSSCs, extensive efforts have been focused on the synthesis of new highly efficient sensitizers. Among the numerous sensitizers, ruthenium polypyridine complexes have received much attention due to their superior performance in DSSCs. In this study, we have designed and synthesized a new series of ruthenium complexes, Ru(tctpy)(L1)(L2) (tctpy = 4,4’,4”-tricarboxy-2,2’:6’,2”-terpyridine, L1 = an anionic bidentate ligand, L2 = an anionic monodentate ligand) . The Ru(tctpy)(L3)(NCS) (dye 1) shows broad metal-to-ligand charge transfer (MLCT) absorption bands in visible region, and its maximum is 515 nm (The structure of L3 will be shown in the presentation). Although, MLCT absorption maximum of dye 1 is blue shifted compared with that of black dye, the molecular extinction coefficient is increased (ε = 8900 M^-1 cm^-1). The photovoltaic performances of the solar cells based on dye 1 were investigated under AM 1.5 irradiation (100 mW cm^-2). The short-circuit current density, open-circuit voltage, fill factor, and overall solar light-to-electrical conversion efficiency were 18.2 mA cm^-2, 626 mV, 0.72, and 8.2%, respectively.

*This work was supported by the Incorporated Administrative Agency New Energy and Industrial Technology Development Organization (NEDO) under Ministry of Economy, Trade and Industry (METI).