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Efficient solar cells on the horizon

Feb. 25, 2009
Boosting the energy efficiency of solar cells is key to making solar energy a realistic and affordable energy source

Boosting the energy efficiency of solar cells is key to making solar energy a realistic and affordable energy source. Much research is being conducted to improve solar technology, with one impressive project taking place at Iowa State University. In Professor Vikram Dalal’s 37 years of researching solar technology, the efficiency of thin film solar cells for homes and buildings has improved from 1% to about 7%.

Dalal, the Thomas M. Whitney Professor of Electrical and Computer Engineering at Iowa State and director of the Microelectronics Research Center, is hoping his latest multidisciplinary research project could boost solar cell efficiency levels to about 10%. The three-year research project is supported by a $1.69 million grant from the Iowa Power Fund, a state program to support energy innovation and independence. The project supports the work of Dalal and six other Iowa State faculty members, plus eight graduate students. The Iowa Energy Center is also supporting some of Dalal’s solar research and he expects that work to contribute to the power fund project.

The project has three primary goals: • Study, characterize, and optimize new silicon alloys that can be used in photovoltaic cells that convert sunlight directly into electricity. Dalal said as new materials are developed, researchers must figure out how they can be used in solar applications. • Develop new solar cell structures that optimize the performance of the new materials. Dalal believes there is no universal design for solar devices and so new materials mean new structures. • Study how semiconductors based on organic molecules can be used in solar applications. Dalal notes that organic molecules are very good at absorbing light and could be the future of solar technology. Researchers are collaborating with PowerFilm Inc. of Ames, Iowa, and Micron Technology Inc. of Boise, Idaho.

 The project includes work in the maturing field of thin film, silicon-based photovoltaic technology, as well as the emerging field of organic semiconductors. “Looking 20 years out, it’s very clear that organic semiconductors will be a major player in photovoltaic technology,” says Dalal. “The technology is in its infancy. And if we don’t nurture a technology in its infancy, how do we grow a mature technology?” That current technology has been a booming business. The Solar Energy Industries Association based in Washington, D.C., reported that the photovoltaic market in the United States grew by more than 48 percent in 2007 and U.S. solar manufacturing grew by 74 percent in 2007. The U.S. currently ranks fourth in the world for installed solar power behind Germany, Japan, and Spain). Solarbuzz, an international solar energy research and consulting company based in San Francisco, reports the photovoltaic industry generated $17.2 billion in global revenues in 2007. “Our whole objective is to achieve greater solar efficiency without sacrificing cost,” says Dalal. “We want to do this better and cheaper. Only then can solar penetrate the large-scale utility market.”

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