Graphene materials and their use in dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) have taken up broad interest as a promising low-cost solar cell technology since they were first reported on in 1991.1 DSSCs use specialized materials for specific cell functions such as photon absorption, charge separation, and charge transport. Triiodide then diffuses to the cathode and is reduced back to iodide, which in turn can diffuse back to the photoanode and continue the cycle. A primary reason for the success of the iodide/triiodide mediator is that electron transfer from the photoanode to triiodide is slow, reducing recombination in the solar cell. To advance performance and lower cost, incorporation of new materials and processing techniques is actively pursued. For instance, organic dyes, which avoid the use of rare earth metals, have been developed which have extinction coefficients an order of magnitude greater than the traditional ruthenium complexes.