The effect of dye coverage on the performance of dye-sensitized solar cells with a cobalt-based electrolyte

Abstract

The effect of dye coverage of the mesoporous TiO₂ electrode on the performance of dye-sensitized solar cells based on the cobalt tris(bipyridine) electrolyte and the D35 dye was studied in detail. The dye coverage was controlled by using a dye bath with different dye concentrations and containing an inert salt, LiClO₄, which was found to promote equilibrium conditions in the dye adsorption process. The amount of adsorbed D35 dye on mesoporous TiO₂ was reasonably fit using the Langmuir adsorption isotherm, with a binding constant of 55 000 M⁻¹. Upon increasing the dye coverage on the TiO₂ electrode, the electron lifetime in the dye-sensitized solar cell increased remarkably, demonstrating the blocking behavior of the D35 dye at the TiO₂–electrolyte interface. Consequently, the solar cell efficiency increased dramatically with the D35 dye coverage.