Characterization of New Ru Complex Dyes for Dye-Sensitized Solar Cells which Have High Extinction Coefficient

  • Kazuteru Nonomura, Department of Physical and Analytical Chemistry, Uppsala University, Sweden
  • Yunhua Xu, Organic Chemistry. Center of Molecular Devices, Department of Chemistry, KTH Chemical Science and Engineering, Stockholm, Sweden
  • Tannia Marinado, Department of Physical and Analytical Chemistry, Uppsala University, Sweden
  • Gerrit Boschloo, Department of Physical and Analytical Chemistry, Uppsala University, Sweden
  • Licheng Sun, Organic Chemistry. Center of Molecular Devices, Department of Chemistry, KTH Chemical Science and Engineering, Stockholm, Sweden
  • Anders Hagfeldt, Department of Physical and Analytical Chemistry, Uppsala University, Sweden

    • New Ru-complex dyes were synthesized for dye-sensitized solar cells (DSSCs) to increase the extinction coefficients and to improve the intramolecular charge separation. Structure of new dyes is shown in figure and dyes are named E311 and E322. Both dyes showed a wide absorption spectrum in the visible region. E322 has a high extinction coefficient of 42000 M-1 cm-1 at 469 nm, and 13000 M-1 cm-1 at 535 nm for E311. Both dyes worked as sensitizers for DSSCs. The obtained efficiency was 3.24, 1.83 % for E311 and E322, respectively. 4.06 % was obtained from N719 as reference. The difference in the photovoltage (624, 538 and 770 mV for E311, E322 and N719, respectively) was one of the key issues to explain the difference of the efficiency. Moreover, dye aggregation especially for E322 diminishes the efficiency significantly. It was observed by photoinduced absorption spectroscopy that the regeneration of the oxidized dye molecules was poor since the dyes were lacking contact with the redox electrolyte due to aggregation. For the cell with E322, an enhancement of the photocurrent was observed during illumination under short-circuit condition with light containing UV. After this treatment, the amount of the adsorbed dye on TiO2 decreased and the regeneration of the oxidized dye started to work well. The total efficiency was improved 2-10 times by this treatment. The details will be discussed in the poster.