Plan to turn rooftops, walls and windows into cheap solar cells
By Jeff Salton
August 25, 2009
Cheaper solar cells – roughly one-tenth the cost of current day prices – could be available within three to five years thanks to a manufacturing procedure that uses nanoparticle ‘inks’ to print them like newspaper or to spray-paint them onto the sides of buildings or rooftops. Even windows could become solar cells thanks to the semi-transparent inks. 'Painting' solar cells on buildings has been an idea in the making for some time – Gizmag investigated the possibilities of 'solar paint' in 2008.
For the past two years, chemical engineer Brian Korgel and his team at the University of Texas, Austin, have been working on reducing solar cell manufacturing costs by 90%. The current process for making solar cells – gas-phase deposition in a vacuum chamber – requires high temperatures and is quite expensive.
Korgal, 31, believes that solar cells need to be relatively inexpensive to make photovoltaics widely adopted. “The sun provides a nearly unlimited energy resource, but existing solar energy harvesting technologies are prohibitively expensive and cannot compete with fossil fuels.”
Korgel’s ink-based solution uses low-cost, nanomaterials to create the solar cells. The inks could be printed on a roll-to-roll printing process on a plastic substrate or stainless steel for durability. And the prospect of being able to paint the ‘inks’ onto a rooftop or building is not far-fetched.
“You’d have to paint the light-absorbing material and a few other layers as well,” Korgel said. “This is one step in the direction towards paintable solar cells.”
Korgel uses the light-absorbing nanomaterials, which are 10,000 times thinner than a strand of hair, because their microscopic size allows for new physical properties that can help enable higher-efficiency devices.
Since 2002, his company Innovalight has been producing silicon-based inks, however, this time Korgel and his team are using copper indium gallium selenide (CIGS), which is both cheaper and more benign in terms of environmental impact.
“CIGS has some potential advantages over silicon,” Korgel said. “It’s a direct band gap semiconductor, which means that you need much less material to make a solar cell, and that’s one of the biggest potential advantages.”
Already his team has developed solar-cell prototypes with efficiencies at one percent; however, they need to be about 10 percent.
“If we get to 10 percent, then there’s real potential for commercialization,” Korgel said. “If it works, I think you could see it being used in three to five years.”
He also said that the inks, which are semi-transparent, could help make windows double as solar cells. No wonder his work has attracted the interest of industrial partners.
Funding for the research comes from the National Science Foundation, the Welch Foundation and the Air Force Research Laboratory.
He is collaborating with professors Al Bard and Paul Barbara, both of the Department of Chemistry and Biochemistry, and Professor Ananth Dodabalapur of the Electrical and Computer Engineering Department. The group recently showed proof-of-concept in a recent issue of Journal of the American Chemical Society.
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