COLORS OF THE SUN

This is not pure research. This is research in one of the most intensely competitive scientific races going right now, the race to produce cost-competitive solar energy electricity. Build a better solar cell and the world will beat a path to your door.

Researchers Thin Pink to Produce “Green” Solar Emergy
30 July 2007 (Ohio State University Live Science via Newswise)

WHO
Yiying Wu, assistant professor of chemistry, postdoctoral researcher Bing Tan, doctoral student Yanguang Li, and undergraduate student Elizabeth Toman.

A DSSC solar cell schematic (click to enlarge)

WHAT
New pink dye-sensitized solar cells (DSSCs) capable of half the efficiency of silicon-based solar cells at a quarter the cost have been tested by Ohio State University researchers. Instead of the blue color of silicon cells, the DSSCs are pink from the red of ruthenium and the white of titanium or zinc oxide.

WHEN
- Recently published. Not yet ready for commercial use.
- Silicon-based cells -- blue from anti-reflective coating to boost absorption of green (strongest wavelength in solar light spectrum) have been around since the 1960s. DSSCs, w/o any anti-reflective coating, have been experimented with since the 1990s. These pink DSSCs are the first not made from simple oxides.

WHERE
Ohio State University is in Columbus, Ohio. The research was published in Journal of the American Chemical Society (JACS)

WHY
- The color of the cell determines the wavelengths of light absorbed, This determines voltage and current, the factors affecting the efficiency of panel’s energy transference.
- These DSSCs are made from zinc stannate, a more complex metal with different particle shapes that boost the electricity produced.
- Dye molecules capture light energy and release electrons which travel along electrical wires. The next step in developing efficiency will be including nano-wires or nano-trees, possibly titanium oxide, in the structure.
- Other dyes or dye combinations may work better.
- Great article on DSSCs at Wikipedia

A more detailed DSSC schematic (click to enlarge)

QUOTES
- Wu: "We believe that one day, DSSC efficiency can reach levels comparable to any solar cell…The major advantage of DSSCs is that the cost is low. That is why DSSCs are so interesting to us, and so important."
- Wu: "This opens up new possibilities for how scientists may tailor the properties of DSSCs in the future…"
- Wu: "If you want to achieve the best efficiency, you need to consider both the voltage you can achieve and the current you can achieve…If you absorb a very broad range of wavelengths, that's going to sacrifice voltage. And if your absorption energy threshold is very high, you can achieve high voltage, but you'll sacrifice current. The idea is to find some balance."