Novel Amphiphilic Ruthenium Sensitizer with Hydrophobic Thiophene or Thieno(3,2-b)thiophene-Substituted 2,2′-Dipyridylamine Ligands for Effective Nanocrystalline Dye Sensitized Solar Cells

Hydrophobic conjugated 2,2′-dipyridylamine substituted amphiphilic ruthenium complexes { cis -Ru(dcbpy)(L)(NCS) 2, where dcbpy is 4,4′-dicarboxylic acid-2,2′-bipyridine and L is 4,4′-di(5-hexylthiophen-2-yl)-2,2′-dipyridylamine, JK-85, or 4,4′-di[5-hexylthieno(3,2- b )thiophene]-2,2′-dipyridylamine, JK-86 } were newly designed, synthesized, and successfully used as sensitizers for nanocrystalline dye sensitized solar cell using an electrolyte consisting of 0.6 M 1,2-dimethyl-3-propylimidazolium iodide (DMPII), 0.05 M I 2, 0.1 M LiI, and 0.5 M tert -butylpyridine in acetonitrile. Under standard AM 1.5 sunlight, the complex JK-86 yielded a short-circuit photocurrent density of 18.3 mA/cm 2, an open-circuit voltage of 0.68 V, and a fill factor of 0.72, corresponding to an overall conversion efficiency of 9.03%. Importantly, the cell exhibits an excellent stability, revealing almost no change after 1000 h of light soaking at 60 °C using a quasi-solid-state electrolyte composed of 0.1 M I 2, 0.5 M NMBI ( n -methyl-benzimidazole), 0.6 M DMPII (1-propyl-2,3-dimethylimidazolium iodide), and 5 wt % PVDF-HFP (poly(vinylidene fluoride- co -hexafluoropropylene)) in MPN (3-methoxypropionitrile).