Lower-cost solar cells to be printed like newspaper, painted on rooftops

August 24, 2009,
At the core of Korgel's research are the nanoparticle "inks" (as shown here) which are the sunlight-absorbing materials of his solar cells. Credit: Beverly Barrett, UT Engineering Public Affairs

Solar cells could soon be produced more cheaply using nanoparticle "inks" that allow them to be printed like newspaper or painted onto the sides of buildings or rooftops to absorb electricity-producing sunlight.

Brian Korgel, a University of Texas at Austin chemical engineer, is hoping to cut costs to one-tenth of their current price by replacing the standard manufacturing process for solar cells - gas-phase deposition in a , which requires high temperatures and is relatively expensive.

"That's essentially what's needed to make solar-cell technology and photovoltaics widely adopted," Korgel said. "The sun provides a nearly unlimited resource, but existing solar energy harvesting technologies are prohibitively expensive and cannot compete with fossil fuels."

Chemical engineering Professor Brian Korgel tests one of his printed solar cells. Credit: Beverly Barrett, UT Engineering Public Affairs

For the past two years, Korgel and his team have been working on this low-cost, nanomaterials solution to photovoltaics - or solar cell - manufacturing. Korgel 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. They recently showed proof-of-concept in an issue of .

The inks could be printed on a roll-to-roll printing 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 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.

In 2002, he co-founded a company called Innovalight, based in California, which is producing inks using silicon as the basis. This time, Korgel and his team are using copper indium gallium selenide or CIGS, which is both cheaper and benign in terms of environmental impact.

Researchers apply the nanoparticle "inks" as a spray on the solar cells. Credit: Beverly Barrett, UT Engineering Public Affairs
"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."

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 realize the prospect of having windows that double as . Korgel said his work has attracted the interest of industrial partners.

More information:
• DOI: 10.1021/ja8080605
• DOI: 10.1021/ja8085438

Source: University of Texas at Austin (news : web)

Explore further: Low-cost solution processing method developed for CIGS-based solar cells

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3 / 5 (3) Aug 24, 2009
Efficiencies need to jump from 1% to 10%? That's a pretty big jump.

Even if 10% efficiency is attained and cost kept at 1/10 of current techniques (that are somewhere around 35% efficient if I'm not mistaken)... then that still only gives an overall advantage of about 3:1. And that's ONLY if current cost advantages can be maintained. This doesn't appear to be as big of a jump (is price per watt) as one would think when first reading the article.
2.7 / 5 (3) Aug 24, 2009
Silicon ink is interesting because silicon is an abundant material, in sharp contrast with the CIGS materials that are rare.

An efficiency of 10% is required, while it is 1% today. Please continue researching silicon ink and forget about the CIGS!

How much extra energy is needed for the production of silicon ink compared with the usual solar grade silicon wafers?
2.3 / 5 (3) Aug 24, 2009
Keep up the good work, at least these guys are involved in the development of a solution.

But given our current (CO2) situation this seems like a very rudimentary embryonic stage technology. One percent efficiency is utterly useless and the risk that 10% will be unattainable is high so I hope that there are hundreds of different labs looking into this because we don't really have time for failure.

2 / 5 (4) Aug 24, 2009
Looks very similar to the already-in-production NanoSolar process. a) Is NanoSolar already using his previous version of ink? b) is the CIGS bit the main item of interest?

Yes nanosolar makes CIGS.

The author should have made him address the NanoSolar issue.

1 / 5 (2) Aug 25, 2009
What about dust/dirt, wind and snow? How do they stack up, or will we see billions of 'solar' newspapers flying all over the place?
3 / 5 (2) Aug 25, 2009
More importantly how does it look? Would people want to cover every square foot with something that looks horrible?
not rated yet Aug 25, 2009
fantastic potential just what we need. Please keep up this excellent research.
1 / 5 (1) Aug 25, 2009
Environmental problems ?
5 / 5 (1) Aug 25, 2009
I think this is the third PhysOrg article I've read this week that has given The Solution to the energy crisis. Why am I getting jaded?
not rated yet Aug 30, 2009
I think this is the third PhysOrg article I've read this week that has given The Solution to the energy crisis. Why am I getting jaded?

I've been hearing how solar cells will soon be cheaper than any other form of energy and is going to solve all our problems for two decades now.

This is doubly irritating, since even if solar panels were free, they wouldn't really solve much of anything. They'd just create a new kind of energy consumption that can absorb this big spike of energy production and they'd leave essentially all the old power-consumption where quality and reliability is more important than quantity intact.

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