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
