Complex Formation with the Iodide Electrolyte Influences Electron Dynamics in Dye-Sensitized Solar Cells

Ground state complexes between the components of the iodide/triiodide redox couple and D149, a wellknown organic dye used in dye sensitized solar cells, have been detected in acetonitrile and on semiconductor surfaces. Generally, in acetonitrile, these complexes have high formation constants in the case of the donor moiety of D149, D149ester and D149. These complexes adsorb on semiconductor surfaces and show different electron dynamics on ZrO2 and TiO2 in comparison to D149 itself. Such complexes on semiconductor surfaces can certainly limit the efficiency of a working cell based on similar organic dyes.