Structural Effect of Donor in Organic Dye on Recombination
in Dye-Sensitized Solar Cells with Cobalt Complex Electrolyte
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Abstract
The effect of the
donor in an organic dye on the electron lifetime
of dye-sensitized solar cells (DSSCs) employing a cobalt redox electrolyte
was investigated. We synthesized organic dyes with donor moieties
of carbazole, coumarin, triphenylamine, and <i>N</i>-phenyl-carbazole
and measured the current–voltage characteristics and electron
lifetimes of the DSSCs with these dyes. The cell with the triphenylamine
donor dye produced the highest open circuit voltage and longest electron
lifetime. On the other hand, the lowest open circuit voltage and shortest
electron lifetime was obtained with coumarin donor dye, suggesting
that the coumarin attracted the cobalt redox couples to the surface
of the TiO<sub>2</sub> layer, thus increasing the concentration of
cobalt complex. On the other hand, the longest electron lifetime with
triphenylamine was attributed to the blocking effect by steric hindrance
of the nonplanar structure of the donor