[font face=Times, Times New Roman, Serif][font size=5]Nanoshell whispering galleries improve thin solar panels[/font]
[font size=4]Engineers at Stanford have created photovoltaic nanoshells that harness a peculiar physical phenomenon to better trap light in the solar materials. The results could dramatically improve the efficiency of thin-film solar cells while reducing their weight and cost.[/font]

By Andrew Myers

[font size=3]Visitors to Statuary Hall in the U.S. Capitol Building may have experienced a curious acoustic feature that allows a person to whisper softly at one side of the cavernous, half-domed room and for another on the other side to hear every syllable. Sound is whisked around the semi-circular perimeter of the room almost without flaw. The phenomenon is known as a whispering gallery.

[font size=1]A scanning electron microscope (SEM) image of a single layer of nanocrystalline-silicon shells. The hollow shell structure improves light absorption while reducing the cost and weight of the device.
Image: Yan Yao[/font]

In a paper published in Nature Communications, a team of engineers at Stanford describes how it has created tiny hollow spheres of photovoltaic nanocrystalline-silicon and harnessed physics to do for light what circular rooms do for sound. The results, say the engineers, could dramatically reduce materials usage and processing cost.

“Nanocrystalline-silicon is a great photovoltaic material. It has a high electrical efficiency and is durable in the harsh sun,” said Shanhui Fan, a professor of electrical engineering at Stanford and co-author of the paper. “Both have been challenges for other types of thin solar films.”

The downfall of nanocrystalline-silicon, however, has been its relative poor absorption of light, which requires thick layering that takes a long time to manufacture.

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