60-Second Science

Solar Energy Harvesting Using 1 Percent of Current Materials

A study in the journal Nature Materials details the creation of a nanowire-based technology that absorbs solar energy at comparable levels to currently available systems while using only 1 percent of the silicon material needed to capture photons. Cynthia Graber reports

Imagine a world where sunlight can be captured to produce electricity anywhere, on any surface. The makers of thin-film flexible solar cells imagine that world too. But a big problem has been the amount of silicon needed to harvest a little sunshine.

Now, researchers [led by Harry A. Atwater] at Caltech say they’ve designed a device* that gets comparable solar absorption while using just one percent of the silicon per unit area that current solar cells need. The work was published in the journal Nature Materials.

The research team tried silicon wire arrays instead of traditional silicon panels. These wires have been shown to do a good job converting sunlight to usable energy on the nanoscale. But the scientists had to create wires a thousand times longer.

Light bounces around within the wires and is eventually absorbed when it hits at the correct angle. But there was a problem: too much light was leaking out. Adding nanoparticles of alumina kept much more of the light scattering until it got absorbed. The result is a system that virtually matches silicon wafer light absorption and may be more efficient at converting light to electricity, while using a tiny fraction of the material.

—Cynthia Graber

[The above text is an exact transcript of this podcast.]

For more, check out the article Photovoltaic Breakthroughs Brighten Outlook for Cheap Solar Power

[Scientific American is part of Nature Publishing Group.]

*Clarification (2/16/10): The Caltech scientists did not invent a “device” in the common sense. They designed a material that absorbs virtually equivalent numbers of photons, yet requires only a tiny percentage of the silicon found in traditional solar cells.


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