TUESDAY 02 MARCH, 2010 |
Caltech Creates Solar Cell Using Silicon Wire Arrays
Researchers at the California Institute of Technology (Caltech) have created a new type of flexible solar cell that enhances the absorption of sunlight
while maintaining high efficiency. The solar cell uses arrays of long, thin silicon wires embedded in a polymer
substrate, requiring a fiftieth of the silicon used by conventional silicon
The silicon-wire arrays absorb up to 96 percent of incident sunlight at a single wavelength and 85 percent of total collectible
sunlight, surpassing previous optical microstructures developed to trap
The silicon wire arrays created by the Caltech team are able to convert between 90 and 100 percent of the photons they absorb into
electrons. In the solar cells, each silicon wire is independently a
high-efficiency; high-quality solar cell says Harry Atwater, Howard Hughes
Professor, professor of applied physics and materials science, and director of
Caltech's Resnick Institute.
Each wire measures between 30 and 100 microns in length and only 1 micron in diameter.
"The entire thickness of the array is the length of the wire, but in terms of area or volume, just 2 percent of it is silicon, and 98 percent is
polymer." says Professor Atwater.
As silicon is an expensive component of a conventional solar cell, this
technology using just one-fiftieth of the amount will mean solar cells would be
much cheaper to produce. The flexibility of the cells will also reduce price as flexible thin films can be manufactured in a roll-to-roll process, an inherently lower-cost process
than the manufacture of rigid, conventional solar cells.
The Caltech team will now focus on increasing the operating voltage and the overall size of the solar
cell and Professor Atwater says the team is well on its way to demonstrating
that conventional sized cells will work just as efficiently as the small
versions already produced.
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