Three thiocyanate-free ruthenium (II) sensitizers, [RuII(dcppy)(L1-L3)](PF6)] where dcppy = 4, 4-dicarboxylic acid-2, 2-bipyridine, L1 = 2-(2,4-difluorophenyl)-5-(trifluoromethyl) pyridine, L2 = 2-(2,4-difluorophenyl) pyridine and L3 = 2-phenyl-5-(trifluoromethyl) pyridine were synthesized and applied for dye-sensitized solar cells (DSSCs). The structures of ruthenium complexes were characterized by 1H, 13C NMR and IR spectra. The absorption was studied by UV-Vis spectroscopy and the electrochemical property was determined by cyclic voltammetry. The surface morphology of ruthenium complexes on mica was examined by atomic force microscopy. The performance of this complexes as photosensitizer in TiO2 based dye sensitized solar cells is studied under standard AM 1.5 sunlight and by using an electrolyte.

The four thiocyanate free ruthenium(II) complexes; [Ru(N^N)2(C^N)]PF6were synthesized and characterized for dye sensitized solar cells (DSSCs). The results showed that the broad absorptions covered the visible region from metal to ligand charge transfer (MLCT) were obtained with the main peaks at 560, 490 and 400 nm. The materials were studied DSSC performance under standard AM 1.5. Compound PP1 showed the power conversion efficiency (PCE) at 3.10%, with a short-circuit photocurrent density (Jsc) of 7.99 mA cm-2, an open-circuit photovoltage (Voc) of 563 mV and a high fill factor (ff) of 0.690.