Abstract A new extended thermo-stable high molar extinction coefficient bipyridyl ruthenium (II) complex “cis-Ru (4, 4'-bis (3, 5-di-tert-butylphenyl)-2, 2'-bipyridine)(L n)(NCS) 2 H 101”, where L n= 4, 4'-dicarboxylic acid-2, 2'-bipyridine; was synthesized and characterized by 1 H- NMR, FT-IR and ESI-MASS spectroscopes. The H 101 sensitized solar cell constructed with an active area of 0.54 cm 2 in combination with an ionic liquid electrolyte exhibited ...