P206
Dye Sensitized Solar Cells: Energetic Considerations and Applications
Brian A. Gregg, Arie Zaban, and Suzanne Ferrere
National Renewable Energy Laboratory
The only substantial electric field in dye sensitized solar cells
is expected to occur at the TiO2/solution interface, that is, across the
electrochemical double layer, and it is primarily here that the
photopotential drops in operating cells. The sensitizing dye is located
partially inside this layer so its redox potential is not fixed relative to
either the TiO2 or the solution. The photovoltage-limiting kinetic step
can depend on the position of the dye in the double layer. In the dark,
the low conductivity of the TiO2 and the high conductivity of the solution
ensure that applied potentials drop over only a small fraction of the
nanoporous TiO2 film near the substrate electrode. Therefore, measurements
in the dark cannot be directly compared to measurements under illumination.
The narrow absorption spectra of many dyes provides the dye cells with a
natural advantage over conventional solar cells in applications such as
photoelectrochromic windows and power windows.
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