Solar Cells and Cities of The Future
March Meeting 2010
WASHINGTON, D.C. — When materials scientist Yang Yang of the University of California, Los Angeles looks at the tall office buildings surrounding his urban campus, he sees opportunities. Many of them have partly tinted windows to curtail the bright Californian sun, and Yang dreams of covering them with a different kind of tint—semi-transparent, semi-conducting panels of carbon-based solar cells that draw energy from the sun even as they shade the conference rooms of downtown L.A.
Expanding our sources of renewable energy is critical for the future, notes Yang, and one way to do it will be to greatly expand the use of solar panels, moving from a few panels on isolated urban rooftops to covering entire buildings with them. "In order to do so," he says, "one must make sure they are very low-cost."
One obvious way to contain cost would be to use cheaper materials. Yang and his colleagues are designing a new generation of solar cell fabricated on top of semiconducting polymers—essentially plastic—rather than the brittle, opaque silicon backing normally used. They have already developed an early prototype, and the technology has been licensed to a company in California, which is commercializing it. Yang predicts that the technology will be commercially available in just a few years. Currently their device converts energy from the sun to electrical energy at nearly 8 percent efficiency, which is less than the industry standard for commercial solar panels (those approach 20 percent). Even so, the polymer materials used in his cells are so inexpensive that Yang predicts they will produce the same amount of energy as commercial panels for a quarter of the cost. He is now designing a stacked "tandem" polymer-based solar cell that he hopes will achieve 12-15 percent efficiency.
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