Using Energy Relay Dyes to Increase Light Absorption in Dye-Sensitized Solar Cells


Improved efficiency for dye-sensitized solar cells is provided using a combination of dyes that have distinct roles--a sensitizing dye and an energy relay dye. The sensitizing dye is disposed on the surface of a photo-electrode and is capable of absorbing incident radiation and of transferring charge at the photo-electrode surface. The energy relay dye is disposed in the electrolyte of the solar cell. The energy relay dye is capable of absorbing incident radiation and is capable of non-radiative energy transfer to the sensitizing dye. The energy relay dye need not be capable of direct charge transfer at the photo-electrode surface. We have found that the presence of such an energy relay dye can significantly increase solar cell efficiency compared to conventional dye-sensitized solar cell approaches having the dye (or dyes) all adsorbed to the photo-electrode surface. In an experiment a 26% increase in power conversion efficiency was obtained when using an energy relay dye (PTCDI) with an organic sensitizing dye (TT1).


This technology allows you to increase the total number of dye molecules inside the device and thus increase overall light harvesting. It is possible to design systems that would absorb light from 400-1000nm significantly improving device performance. Because the energy relay dyes do not participate in charge transfer the design rules for candidates are significantly relaxed. Chromophores that would not work as a sensitizing dye can work as a relay dye. This is a low-cost easy to implement design in conventional dye-sensitized solar cells.

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