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Flywheel Energy Storage Researchers at the University of Texas have found that quantum dots could double the efficiency of solar cells

Published on June 20th, 2010 | by Tina Casey


Quantum Dots Could Boost Solar Efficiency by 100%

June 20th, 2010 by  

Researchers at the University of Texas have found that quantum dots could double the efficiency of solar cellsResearchers at the University of Texas at Austin are hot on the heels of a discovery that could more than double the efficiency of solar cells. The trick is to use tiny nanoscale crystals called quantum dots to capture more of the available energy in sunlight, including energy at the high end of the scale.  The researchers estimate that the use of high energy sunlight could boost efficiency from its present rate of about 31% for conventional solar cells, up to a whopping 66%.

Update: A team from The University of Minnesota initiated this research.

What this all means is the potential for solar energy to become cost-competitive with fossil fuels at an increasingly rapid pace.  Paired with next-generation flywheels and other new energy storage technologies, intermittent sources such as solar and wind can provide an energy stream that is every bit as steady and reliable as oil, coal, or natural gas.

Quantum Dots and Solar Cell Efficiency

High energy sunlight comes in the form of “hot electrons.” Until now, that energy has been too hot to convert into electricity, and it escape as heat.  The researchers, headed by chemist Xiaoyang Zhu,  found a way to conduct the hot electrons out by using quantum dots, which have conductive properties that can be precisely controlled.  Their work is built on a foundation recently established by another team from the University of Chicago, which showed that a specific type of nanocrystal can be used to control the rate at which hot electrons cool down.

Non-Toxic Quantum Dots

Conventional quantum dots are made of toxic heavy metals, and Zhu’s research was carried out on quantum dots made of lead selenide, a crystalline form of lead. However, Zhu notes that other materials could also be used, opening up the potential to construct a high efficiency solar cell with quantum dots made of non-toxic materials.  Magnolia Solar, for example, is one company that has developed thin film solar technology based on non-toxic quantum dots.  Quantum dots made of diamond nanocrystals are also in development.  The wonder material graphene and its newly discovered mate graphane could also offer another non-toxic route.

The True Cost of Fossil Fuels

Fossil fuels can perhaps be credited with enabling the U.S. to power itself up without burning every stick of wood from coast to coast for fuel, but just as we no longer rely on wood as our prime source of energy, it is clear that in the future we will no longer rely on fossil fuels.  Their true cost has become evident as clean-up for the Gulf Coast oil spill is in the tens of billions, coal mining has long been associated with chronic poverty and health problems throughout the entire Appalachian region as well as surface damage related to undermining and underground coal fires, and natural gas recovery from shale deposits threatens water supplies and may make it necessary to invest billions in new water treatment facilities.

Image: Dots by {AndreaRenee} on

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About the Author

specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.

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    • Tina Casey

      Hi Doris thank you for the thank you.

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  • Douglas Hvistendahl

    When the heat is used also (PVT technology) efficiency jumps to around 70%. What is needed is to work out ways to use the heat economically.

  • Right now solar cells efficiency is still low,i hope more and more new technology will shows up to raise the efficiency.

  • b r clark

    31% is much too high. That is a theoretical number for PV cells with no concentration. Realistic conversion efficiency numbers for real world modules vary from the low to upper teens depending on the technology. Lower for thin films PV like First Solar and higher for monocrystalline PV like Suniva.

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