The high molar extinction coefficient heteroleptic ruthenium dye, NaRu(4,4'-bis(5-(hexylthio)thiophen-2-yl)-2,2'-bipyridine) (4-carboxylic acid-4'-carboxylate-2,2'-bipyridine) (NCS)(z), exhibits certified 5% electric power conversion efficiency at AM 1.5 solar irradiation (100 mWcm(-2)) in a solid-state dye-sensitized solar cell using 2,2',7,7'-tetrakis-(N,N-dipmethoxyphenylamine)-9,9'-spirobifluorene (spiro-MeOTAD) as the organic hole-transporting material. This demonstration elucidates a class of photovoltaic devices with potential for low-cost power generation. (C) 2010 Elsevier Ltd. All rights reserved.