Spinach + Silicon = Powerful Solar Cell


Remember when your parents used to pester you about eating your spinach? Even Popeye touted spinach as a great way to pump up those biceps. Well, it looks as though they were right. Spinach is proving to be a valuable green. And not just for your body, but for environmental science as well!

There are reports that the photosynthetic protein in spinach, combined with silicon, results in a solar cell that produces considerably more electrical current than any previous “biohybrid” solar cells. The combination was tested as part of a research project at Vanderbilt University in Nashville, Tennessee.

Environmental blog, CleanTechnica.com quotes David Cliffel. He’s associate professor of chemistry at Vanderbilt and participated in the project: “This combination produces current levels almost 1,000 times higher than we were able to achieve by depositing the protein on various types of metals. It also produces a modest increase in voltage. If we can continue on our current trajectory of increasing voltage and current levels, we could reach the range of mature solar conversion technologies in three years.”

For the next phase, the team reportedly plans to build a functional PS1-silicon solar cell using this new design.

CleanTechnica reports that the researchers estimate the new design could allow a two-foot panel to put out at least 100 milliamps at one volt. That’s enough to power a number of different types of small electrical devices.

More than 40 years ago, scientists discovered that one of the proteins involved in photosynthesis (PS1) was able to function even after it was extracted from plants. Moreover, PS1 impressively converts sunlight into electrical energy with nearly 100 percent efficiency. According to CleanTechnica, that’s much more than the conversion efficiencies of less than 40 percent achieved by artificial devices. Since these discoveries, PS1 has been as been sought after as a reliable path to creating very high-efficiency solar cells.

The other advantage of biohybrid solar cells is that they can be made from cheap and easily-obtained materials. The materials used in conventional cells, such as platinum or indium, are apparently rare and very expensive.

CleanTechnica goes on to report that the reason why PS1 and silicon make such a good combo is because “the electrical properties of the silicon substrate have been tailored to fit those of the PS1 molecule.” This was done by implanting electrically charged atoms into the silicon in order to alter its electrical properties. This process is aptly known as “doping”.

The PS1 protein was found to work extremely well with silicon doped with positive charges. And very poorly with negatively doped silicon.