Wednesday, August 6, 2008

New material can absorb infrared, increase solar efficiency


Semiconductor solar cells absorb sunlight from the visible spectrum, ignoring ultraviolet and infrared rays, which limits how much energy a solar cell can create from sunlight. But a new material made by researchers in Spain throws titanium and vanadium into the mix so it can utilize infrared and potentially boost efficiency of solar cells.

The new material provides a �stepping-stone� for electrons to move from one energy level to another as they absorb photons, allowing more photons of different energy levels (and thus different parts of the light spectrum) to be utilized. So while some efficiency research goes into breaking down what is absorbed into specific wavelengths or trapping light for greater absorption, this technology basically casts a really wide net in order to increase how much light can be captured and turned into energy.

Semiconductor solar cells have a theoretical absorption rate of 40% with an actual absorption of about 30%. The new material hasn�t been tested yet for just how much it can gather, but it has a theoretical absorption rate of 63%, so the scientists reason that the actual absorption will be higher than semiconductor solar cells. This is a step up from the first �stepping-stone� solar cells that achieved a theoretical capture rate of 57%.

So far, the early versions of the materials match the properties predicted by the researchers to enable it to absorb infrared. Now we just have to wait for the material to be turned into an actual solar cell so we can know just what the size of this improvement is.

Via TreeHugger, New Scientist; photo via vogelium

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