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. By depositing two or even three layers of nanoshells atop one another, the team teased the absorption of light higher still. With a three-layer structure, they were able to achieve total absorption of 75% of light in certain important ranges of the solar spectrum.