'Fool's gold' could promise cheaper solar future

Researchers at the University of California, Berkeley, and the Lawrence Berkeley National Laboratory (LBNL) say they’ve identified several abundant and less expensive alternatives to silicon — including iron pyrite, or “fool’s gold” — that could make solar cells cheaper to produce.

“The reason we started looking at new materials is because people often assume solar will be the dominant energy source of the future,” said Cyrus Wadia, a researcher at LBNL. “Because the sun is the Earth’s most reliable and plentiful resource, solar definitely has that potential, but current solar technology may not get us there in a timeframe that is meaningful, if at all. It’s important to be optimistic, but when considering the practicalities of a solar-dominated energy system, we must turn our attention back to basic science research if we are to solve the problem.”

Most solar cells today are silicon-based or use thin-film technology using cadmium telluride and copper indium gallium selenide. However, silicon has the disadvantage of being difficult to mine and costly to process and produce on a commercial scale, while the thin-film materials threaten resource depletion at mass-production levels.

In addition to iron pyrite, the research team says other unconventional minerals that could be used in solar cells include copper sulfide and copper oxide. A total of 12 different materials are abundant enough to meet or exceed world energy demands, the scientists found, while nine promise a “significant raw material cost reduction” over silicon.

Iron pyrite shows the most promise, however, as its cost and abundance makes it “several orders of magnitude” better than any other alternative, the researchers say.