title: New photosensitizers containing the dipyridoquinoxaline moiety and their use in dye-sensitized solar cells.
abstract: New Ru(II) polypyridyl complexes containing two N, N bidentate ligands, [Ru(phendione)2dpq(COOH)2](BF4)2 (L101), {Ru(phendione)[dpq(COOH)2]2}(BF4)2 (L102) and [Ru(phendione)dpq(COOH)2 (SCN)2](L103), (phendione=5,6 dione-1,10-phenanthroline and dpq(COOH)2=6,7-dicarboxylicdipyrido[2,2-d:2',3'f]quinoxaline) have been synthesized and characterized, and attached to a TiO2 substrate to be tested as solar cell sensitizers. We found that the solar to electricity conversion efficiency of cell is strongly affected by the type of ancillary ligand, the efficiency of L102 (with one phendione moiety) adsorbed on TiO2 nanocrystalline films being 2.5 times as large as that of L101 (with two phendione moieties) adsorbed on the same films. The effect of ancillary ligand on the photovoltaic performance of the complexes was compared to results of computational methods by ab initio DFT molecular dynamics simulations and quantum dynamics calculations of electronic relaxation to investigate the interfacial electron transfer in L101-103/TiO2-anatase nanostructures. It is found that the primary process in the interfacial electron-transfer dynamics involves an ultrafast (τ1=6 fs) electron-injection. The concepts of attribute ancillary ligand substitution and HOMO-LUMO alignment of dye with conduction band of semiconductor and electrolyte redox state are shown very helpful for tuning the photovoltaic properties and the rational architecture of polypyridyl photosensitizer with anticipated good properties.
authors.affiliation: Chemistry Department, University of Zanjan, Zanjan, Iran. Electronic address: shahroos@znu.ac.ir.
authors.forename: Hashem
authors.initials: H
authors.lastname: Shahroosvand
authors.affiliation: Chemistry Department, University of Zanjan, Zanjan, Iran.
authors.forename: Shiva
authors.initials: S
authors.lastname: Rezaei
authors.affiliation: Chemistry Department, University of Zanjan, Zanjan, Iran.
authors.forename: Saeid
authors.initials: S
authors.lastname: Abbaspour
mesh_terms: D004396:Coloring Agents / Q000737:chemistry*; D017319:Photosensitizing Agents / Q000737:chemistry*; D011810:Quinoxalines / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry; D012993:Solar Energy; D014025:Titanium / Q000737:chemistry
chemical_list: D004396:Coloring Agents; D017319:Photosensitizing Agents; D011810:Quinoxalines; C009495:titanium dioxide; D012428:Ruthenium; D014025:Titanium