The redox couple that has been found to be most effective for the regeneration of the sensitizer (dye) in dye-sensitized solar cells is the iodide/iodine couple. The iodide ions donate electrons to the oxidized sensitizer, thereby minimizing the loss of electrons in charge recombination. However, the presence of high concentrations of iodide and iodine increases the probability of their interaction with the excited state of the sensitizer. Thus, ways to minimize the excite-state interaction with the redox couple is important in order to maximize the photoconversion efficiency of a dye-sensitized solar cell.

To this end, we have employed C60 clusters to separate the sensitizer, a Ru(II) complex, and the redox couple to minimize the excited sensitizer-redox couple interactions. It has been observed that the cells with C60 clusters delivered a much higher photocurrent than those without them. C60 clusters, incorporated between the dye and redox couple, shield the dye and, at the same time, act as electron relay to regenerate the dye. The advantage of C60 clusters in diminishing the interaction between excited dye and redox couple is also observed in the suppression of luminescence quenching of the excited dye by iodine following the deposition of a layer of C60 clusters. Various other photochemical and photoelectorochemical properties will also be discussed.