DEC 28

Photovoltaic technology has taken another step forward as researchers at the National Renewable Energy Laboratory (NREL) have demonstrated a photocell with an external quantum efficiency over 100 percent using quantum dots. The new cell uses a process called Multiple Exciton Generation (MEG) that produces more than one electron-hole pair per absorbed photon, and reached a level of 114 percent.

This development offers the possibility of increased efficiency in solar panels, and the technology is able to be manufactured using high-throughput roll-to-roll manufacturing. With the use of quantum dots, photocells could theoretically see as much as a 35 percent increase in power conversion efficiency above contemporary cells. The research cell was constructed as a "layered cell consisting of antireflection-coated glass with a thin layer of a transparent conductor, a nanostructured zinc oxide layer, a quantum dot layer of lead selenide treated with ethanedithol and hydrazine, and a thin layer of gold for the top electrode."

Note that this does not mean that the entire panel would have a total efficiency above 100% (which would be thermodynamically impossible). The quantum efficiency means only that the number of electron-hole pairs created in the cell is greater than the number of photons that are absorbed. Nonetheless, the advance provided by MEG could lead to the next generation of even more efficient solar energy collectors.

image: Lawrence Berkeley Lab and CC-BY-SA 3.0 by Opticks3

Comments (6)

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written by gas processing, December 29, 2011

A simple quantum dot increase the efficiency by 35 percent now that sounds some interesting.

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Correction
written by David, December 29, 2011

Greetings!

Just a minor imperfection in the text:
ethanedithol it's a dithiol, it has two SH groups.

Ence, it's not ethanedithol but ethanedithiol.

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Momentarily Stunned.
written by James Gerard, January 06, 2012

I was briefly stunned into a sort of mind-freeze when I read the phrase "efficiency over 100 percent". Gasp. Funny. I hope this process makes it to production. Sounds great thus far, and would expand the usefulness of Solar Energy to much larger parts of the planet.

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CPV?
written by Zach, February 01, 2012

would this new technology be useful in concentrated photovoltaics? Or would it be best used by itself?

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written by computer recycling, February 07, 2012

Technically a solar cell can produce more energy than the amount of visible light that falls on it if it captures energy from outside of the visible spectrum. That said it would seem more likely that efficiency isn't calculated that way. As an interesting aside, washing powder that claims "whiter than white" results is able to do so because ultra violet light is converted into visible light theyby making it possible for recently washed clothing to actually reflect more visible light than it receives.

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Great news,
written by Solar air heating, February 09, 2012

Great news, but how long before this is at a production stage? If this can be produced without clean room conditions it should help bring costs down to levels where it can compete with regular utility production

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