Hot solar: This solar cell is made of thin layers of amorphous silicon with aluminum dots serving as back electrical contacts. It provides evidence that it may be possible to double the output of solar cells.
Michael Naughton
A novel approach could turn more sunlight into electricity.
For decades researchers have investigated a theoretical means to double the power output of solar cells--by making use of so-called "hot electrons." Now researchers at Boston College have provided new experimental evidence that the theory will work. They built solar cells that get a power boost from high-energy photons. This boost, the researchers say, is the result of extracting hot electrons.
The results are a step toward solar cells that break conventional efficiency limits. Because of the way ordinary solar cells work, they can, in theory, convert at most about 35 percent of the energy in sunlight into electricity, wasting the rest as heat. Making use of hot electrons could result in efficiencies as high as 67 percent, says Matthew Beard, a senior scientist at the National Renewable Energy Laboratory in Golden, CO, who was not involved in the current work. Doubling the efficiency of solar cells could cut the cost of solar power in half.
Conventional solar cells can only efficiently convert the energy of certain wavelengths of light into electricity. For example, when a solar cell optimized for red wavelengths of light absorbs photons of red light, it produces electrons with energy levels similar to those of the incoming photons. When the cell absorbs a higher-energy blue photon, it first produces a similarly high-energy electron--a hot electron. But this loses much of its energy very quickly as heat before it can escape the cell to produce electricity. (Conversely, cells optimized for blue light don't convert red light into electricity, so they sacrifice the energy in this part of the spectrum.)
The Boston College researchers made ultra-thin solar cells just 15 nanometers thick. Because the cells were so thin, the hot electrons could be pulled out of the cell quickly, before they cooled. The researchers found that the voltage output of the cells increased when they illuminated them with blue light rather than red. "Now we're getting the electrons from the blue light out before they lose all of their excess energy," says Michael Naughton, a professor of physics at Boston College.
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Double the power, halve the cost -- of the electricity?
This is sure good news. If this pans out, I assume the cost of the electricity generated will also be cut in half -- making it able to compete with traditional energy sources. And halving the investment-recovery time as well for the panels themselves. Fingers crossed!
Re: Double the power, halve the cost -- of the electricity?
Not necessarily:
The new cells could cost thrirty times as much to make. Indeed initially the big use would be for solar cells that are extremely expensive to get into the proper location: Satellites. As the price comes down they will compete first in remote locations such as communication relay towers, water monitoring stations.
I don't expect them to ever be as cheap as standard solar cells -- they are more complex to make.
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dancrissco
54 Comments
Inkjetting Solar Cells
Sounds a very interesting and viable concept. Can this concept be piezo ink jetted on to panels or directly to the component needing power. Take for instance the pemmPOD concept car. The reason I favor ink jetting solar cells is that we can dramatically reduce the cost of solar cell fabrication.
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erbium
338 Comments
Re: Inkjetting Solar Cells
this would be an insignificant source of power for cars. about the only uses would be current uses - RVs use them to keep batteries from going dead when parked for a while, and a hybrid car uses solar panels to power a fan to draw hot air out of car when parked.
if you inkjetted them sounds like still would have to be on a thin media or sounds like advantage is gone.
first solar and others use roll printing to produce their new type solar cells which are much cheaper than silicon ones. this is similar to inkjet printing.
http://en.wikipedia.org/wiki/First_Solar
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