News and analysis about energy in California with an eye toward renewables.

Graphene May Offer Highly Efficient Solar Cells

Superefficient solar cellls down the road? | Photo: Mike Baker/Flickr/Creative Commons License

Add another item to the growing buzz about graphene, which ReWire has covered quite recently: in addition to being a promising candidate for electrical power storage, the single-atom thin sheet form of carbon may offer a way to squeeze a whole lot more power out of photovoltaic cells.

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Current photovoltaic technology relies on semiconductors that convert individual photons -- light particles -- into individual free electrons, that are then fed into a circuit for use as electrical power. According to a study conducted by the Institute of Photonic Sciences (ICFO) just published in the journal Nature Physics, graphene can produce several such "hot electrons" for each photon that strikes it under certain conditions, suggesting that the substance might offer a way to make solar cells significantly more productive.

Graphene is a crystalline form of pure carbon that has been the subject of recent attention due to its potential for energy storage when used as a matrix for supercapacitors.

The ICFO researchers, led by Frank Koppens and Klaas-Jan Tielrooij, found that graphene can convert a broad spectrum of light frequencies to free electrons, and that some energy that would be lost to heat in other PV semiconductors seems to go into creating additional "hot electrons" in graphene.

The researchers are now working to find ways of capturing those electrons for use to power electrical circuits.

"It was known that graphene is able to absorb a very large spectrum of light colors," said Tielrooij and Koppens in an ICFO press statement. "However now we know that once the material has absorbed light, the energy conversion efficiency is very high. Our next challenge will be to find ways of extracting the electrical current and enhance the absorption of graphene. Then we will be able to design graphene devices that could generate efficient solar power."

In other words, any potential graphene-related jumps in solar cell efficiency are a ways down the road. Still, it's another fascinating piece of news about an increasingly fascinating substance.

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About the Author

Chris Clarke is a natural history writer and environmental journalist currently at work on a book about the Joshua tree. He lives in Joshua Tree.
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