Thin-film solar might be able to have its cake and eat it to.
Generally, going thinner makes a panel cheaper to produce than traditional photovoltaic modules by cutting materials costs; but it also means reduced efficiency. But now U.K. researchers say that a design that includes aluminum studs on the surface of gallium arsenide (GaAs) thin-film panels could boost their efficiency by as much as 22 percent.
The researchers are talking about very small cyclinders, just 100 nanomaters wide – less than the depth of a pit on a compact disc. But under a microscope, they give the appearance of LEGO buildings blocks. The researchers say light bouncing around off the studs travels for longer distances through its absorbing layer, thus boosting absorption and increasing output.
Apparently, the attempt to boost efficiency with this sort of architecture isn’t new – gold and silver have been tried – but the use of aluminum is.
“Gold and silver both have a strong effect on passing light rays, which can penetrate into the tiny studs and be absorbed, whereas aluminium has a different interaction and merely bends and scatters light as it travels past them into the solar cells,” lead author Nicholas Hylton from the Department of Physics at Imperial College London said in a statement.
The researchers see the aluminum studs working well with thin-film panels. Such panels can trim costs, but usually give up some of the efficiency over panels with thicker layers. “This type of broadband enhancement opens up the possibility to move towards producing solar cells with thin-film absorbers, without compromising power conversion efficiencies, thus reducing material consumption,” they wrote in the study.
And of course there’s the fact that aluminum, compared to gold or silver, is cheaper and more plentiful.
The study, “Loss mitigation in plasmonic solar cells: aluminium nanoparticles for broadband photocurrent enhancements in GaAs photodiodes,” is available online at Nature.com.