Within two decades of the advent of the dye-sensitized solar cell (DSC), the efficiency of the TiO2 photoanode-based DSC has been gradually increased to 11%. In order to achieve further substantial increase in the efficiencies, radical approaches might be required. Construction of tandem DSCs, consisting of a dye-sensitized TiO2 photoanode and a dye-sensitized photocathode of a suitable p-type semiconductor, is an attractive approach in terms of extending the open-circuit voltage of the cell. With a judicious choice of the two dyes that sensitize anode and cathode respectively, their combination in a tandem DSC can cover a broader solar spectrum than a single-absorber DSC. Tandem DSCs are also proposed to be suitable from commercialization viewpoint as well, as they would require only marginal extra manufacturing costs when compared to a single-absorber DSC.In order to construct a highly efficient tandem DSC, photocurrent-matching of the anode and the cathode is an essential requirement, because the short-circuit current (Isc) would be limited by the less efficient electrode of the two. In p-type DSCs, dye-excitation is followed by rapid electron transfer from a p-type semiconductor to the HOMO of the dye, and the reduced dye is regenerated when the electron from the LUMO of the excited dye reduces the oxidized form of the redox mediator (typically iodide-triiodide). Currently, the photovoltaic performance of the previously reported p-DSCs has been not efficient, which prohibits the fabrication of high-efficiency tandem DSCs. In this presentation, I will discuss our progress in pursuing more efficient p-DSCs through new semiconductors and sensitizers.

Toward more efficient photocathode for tandem dye-sensitized solar cells

243rd National Meeting (2012)

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