Web Release Date: February 23,
Quinoxaline-Fused Porphyrins for Dye-Sensitized Solar Cells
and
Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan, Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan, Institute for Integrated Cell-Material Sciences (iCeMS), Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan, and Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4, Takano-Nishihiraki-cho, Sakyo-ku, Kyoto 606-8103, Japan
Received: October 28, 2007
In Final Form: December 17, 2007
Abstract:
5,10,15,20-Tetrakis(2,4,6-trimethylphenyl)-6'-carboxyquinoxalino[2,3-
]porphyrinatozinc (II) (ZnQMA) and
5,10,15,20-tetrakis(2,4,6-trimethylphenyl)-6',7'-dicarboxyquinoxalino[2,3-]porphyrinatozinc (II) (ZnQDA)
have been synthesized to evaluate the effects of ,'-carboxyquinoxalino moieties on the structure and optical,
electrochemical, and photovoltaic properties of the porphyrins. Both ZnQMA and ZnQDA exhibited broadened
and red-shifted light absorption in UV-visible absorption spectra compared with 5,10,15,20-tetrakis(2,4,6-trimethylphenyl)porphyrinatozinc (II) (ZnP). ZnQMA and ZnQDA also showed decrease in the highest occupied
molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gap due to the extension of the
porphyrin 
-system. From the results of 1H NMR spectroscopy and DFT calculations, ZnQMA and ZnQDA
were found to adopt saddle and planar structures, respectively. ZnQMA-sensitized TiO2 solar cell with TiO2
nanoparticles (P25) revealed the power conversion efficiency (
) of 5.2%, whereas ZnQDA-sensitized cell
showed = 4.0%. The superior performance of the ZnQMA-sensitized solar cell to the ZnQDA-sensitized
one is originated from both the more favorable electron injection and charge collection efficiency.
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