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New Technique Could Lead To Widespread Use Of Solar Power
Princeton - Sep 12, 2003 Princeton electrical engineers have invented a technique for making solar cells that, when combined with other recent advances, could yield a highly economical source of energy. The results, reported in the Sept. 11 issue of Nature, move scientists closer to making a new class of solar cells that are not as efficient as conventional ones, but could be vastly less expensive and more versatile. Solar cells, or photovoltaics, convert light to electricity and are used to power many devices, from calculators to satellites. The new photovoltaics are made from "organic" materials, which consist of small carbon-containing molecules, as opposed to the conventional inorganic, silicon-based materials. The materials are ultra-thin and flexible and could be applied to large surfaces. Organic solar cells could be manufactured in a process something like printing or spraying the materials onto a roll of plastic, said Peter Peumans, a graduate student in the lab of electrical engineering professor Stephen Forrest. "In the end, you would have a sheet of solar cells that you just unroll and put on a roof," he said. Peumans and Forrest cowrote the paper in collaboration with Soichi Uchida, a researcher visiting Princeton from Nippon Oil Co. The cells also could be made in different colors, making them attractive architectural elements, Peumans said. Or they could be transparent so they could be applied to windows. The cells would serve as tinting, letting half the light through and using the other half to generate power, he said. Because of these qualities, researchers have pursued organic photovoltaic films for many years, but have been plagued with problems of efficiency, said Forrest. The first organic solar cell, developed in 1986, was 1 percent efficient -- that is, it converted only 1 percent of the available light energy into electrical energy. "And that number stood for about 15 years," said Forrest.
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