June 23, 2009

Relay boosts dye solar cells

Add a second dye to a dye-sensitized solar cell, and you can boost the power output from these low-cost solar cells.

Dye-sensitized solar cells use dye molecules to absorb energy from sunlight and pass it on to an inexpensive semiconductor material that converts it to an electric current. The second dye -- an energy relay dye -- absorbs higher energy photons than the solar cell normally absorbs and passes the energy on to the primary dye.

The primary dye coats nanoparticles of the semiconductor material. Energy relay dye molecules float in an electrolyte surrounding the nanoparticles. The energy relay dye transfers energy absorbed from sunlight to nearby primary dye, which also directly absorbs lower-energy photons.

A prototype energy relay dye solar cell converted 26 percent more light to electricity than the same cell without the energy relay dye.

The prototype has a power conversion efficiency of only 3.21 percent. The technique has the potential to push dye-sensitized solar cells to about 15 percent, however.

The best dye-sensitized solar cells are about 12 percent efficient. Commercially available silicon solar cells, which are more expensive, are typically about 20 percent efficient.

Research paper:
Increased light harvesting in dye-sensitized solar cells with energy relay dyes
Nature Photonics, published online June 21, 2009

Researchers' contact:
Michael D. McGehee

Related stories and briefs:
The dyes have it -- related research

Back to ERN June 29, 2009



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