REINVENTING PHOTOVOLTAICS
When Harry Atwater was a student in Pennsylvania during the oil shocks of the 1970s, his elementary school had to close for weeks at a time during the winter because of a fuel shortage. “That made a powerful impres- sion,” says Atwater, now the director of the center for sustainable energy research at the California Institute of Technology, where he has devoted his career to finding a more reliable source of energy. Long an evangelist for photovoltaic solar cells and next-generation thin-film PV materials, Atwater has spent the past few years testing a technology that could reinvent photovoltaics altogether. Instead of cutting silicon into thin- ner and thinner wafers, as many scientists are doing, Atwater is researching ways to make arrays of silicon nanorods, small clusters of wires a hundredth the size of a human hair, convert sunlight into electricity.
Because the wires, bunched to- gether like bristles on a brush, can absorb light along the entire length of each wire—while also “trapping” the sunlight on the semiconductor— a pack of nanorods is much more ef- ficient than a conventional, flat wafer, even though it requires much less silicon. In recent tests, Atwater has found that the wires concentrate light at an intensity five to 10 times greater than traditional solar panels. “It’s one of those things that’s so obvious in ret- rospect, but it works unexpectedly well,” he says. Atwater may not be able to get schools through the winter yet. But he’s getting closer.
U.S.NEWS & WORLD REPORT • WWW.USNEWS.COM • APRIL 2009 page 75