Four novel thiocyanate-free cyclometallted Ru(II) complexes, D-bisCF(3), D-CF3, D-OMe, and D-DPA, with two 4,4'-dicarboxylic acid-2,2'-bipyridine together with a functionalized phenylpyridine ancillary ligand, have been designed and synthesized. The effect of different substituents (R = bisCF(3), CF3, OMe, and DPA) on the ancillary (CN)-N-boolean AND ligand on the photophysical properties and photovoltaic performance is investigated. Under standard global AM 1.5 solar conditions, the device based on DCF3 sensitizer gives a higher conversion efficiency of 8.74% than those based on D-bisCF(3), D-OMe, and D-DPA, which can be ascribed to its broad range of visible light absorption, appropriate localization of the frontier orbitals, weak hydrogen bonds between -CF3 and -OH groups at the TiO2 surface, moderate dye loading on TiO2, and high charge collection efficiency. Moreover, the D-bisCF(3) and D-CF3 based DSSCs exhibit good stability under 100 mW cm(-2) light soaking at 60 degrees C for 400 h. (C) 2015 Elsevier Ltd. All rights reserved.