A heteroleptic polypyridyl ruthenium complex, cis-Ru(4,4-bis(5-octylthieno[3,2-b]thiophen-2-yl)-2,2-bipyridine)(4,4-dicarboxyl-2,2-bipyridine)(NCS)2, with a high molar extinction coefficient of 20.5 × 103 M-1 cm-1 at 553 nm has been synthesized and demonstrated as a highly efficient sensitizer for a dye-sensitized solar cell, giving a power conversion efficiency of 10.53% measured under an irradiation of air mass 1.5 global (AM 1.5G) full sunlight.