Inexpensive full-spectrum solar cells on the horizon

Third band gap increases spectrum utilization
Researchers at the Lawrence Berkeley National Laboratory have developed a new solar cell that utilizes all wavelengths of light and can be produced using current techniques. This last part is the important point, since full-spectrum solar cells have been developed before, but up to now they’ve been very expensive to make.

The new full spectrum cells, created by The Solar Energy Material Research Group in the Materials Science Division at the Department of Energy’s Berkeley Lab, blend different types of solar cell materials to produce different layers that respond to different wavelengths of light.   The cells use an alloy of gallium arsenide nitrate to create two mismatched semiconductors, which then produces a third layer (called a band gap) between the two semiconductor layer.  This third band gap lets the cell utilize the lower energy wavelengths to produce electricity, and during testing the solar cells reacted to the full spectrum of light, from infrared to ultraviolet.    (And the ability to use infrared light means that the cells can produce electricity on cloudy days).   Gallium arsenide nitrate is very similar in composition and cost to the gallium arsenide that’s used in many solar cells today – it just replaces some of the arsenic atoms with nitrogen.

The research team, led by Wladek Walukiewicz, says that the alloy can be made with the same process used to make gallium arsenide – chemical vapor deposition, which means that these  more efficient solar cells can be produced using the same techniques available today.

via: Business Green

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