Solar cells nano-inked onto rooftops

TEXAS-AUSTIN (US)—Solar cells may soon be much cheaper to produce thanks to nanoparticle “inks” that could potentially be painted onto buildings or rooftops to absorb sunlight.

Brian Korgel, a University of Texas at Austin chemical engineer, is hoping to cut solar cell manufacturing costs to one-tenth of their current price by replacing the standard process with a low-cost, nanomaterials solution. Korgel and his team showed proof-of-concept in a recent issue of Journal of the American Chemical Society.

Lowering the cost is “essentially what’s needed to make solar-cell technology and photovoltaics widely adopted,” Korgel says. “The sun provides a nearly unlimited energy resource, but existing solar-energy harvesting technologies are prohibitively expensive and cannot compete with fossil fuels.”

The inks could be printed using a roll-to-roll process on a plastic substrate or stainless steel. 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 says. “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.

In 2002, he cofounded a company that produces inks using silicon as the basis. Korgel and his team now are using copper indium gallium selenide, or CIGS, which is both cheaper and benign in terms of environmental impact.

“CIGS has some potential advantages over silicon,” Korgel explains. “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.”

His team has developed solar-cell prototypes with efficiencies at 1 percent—although, the goal is about 10 percent.

“If we get to 10 percent, then there’s real potential for commercialization,” Korgel says. “If it works, I think you could see it being used in three to five years.”

He also says the inks, which are semitransparent, could help realize the prospect of having windows that double as solar cells. Korgel says 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.

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