Friday, October 3, 2014

Perovskite—the next solar cell wonder material?

One of the things that critics of solar energy forget is that it is still a VERY young industry.  The cells 10 years from now will probably be a lot better because there is a lot of room for improvement in design and materials.  The fact that solar is changing so rapidly is certainly no excuse not to get in with both feet.  Because while the technology is still a moving target, good solar sites are not.  A good solar site will make electricity no matter the state of the technology.

Will perovskite become the next wonder material in PV?  Who knows?  Certainly not me.  I remember when a 27 GB hard drive for $300 was this incredible bargain and that certainly the physical limits of magnetic storage were in sight.  I thought about that yesterday was I was reading an ad for a 5 TB HDD for $300. But it seems like at this stage of the game, it would be silly not to keep track of the materials and processes that have significant upside potential and perovskite seems to fit the bill.

Perovskite Offers Shot at Cheaper Solar Energy

Rapid Gains in Efficiency Make This Class of Compounds a Potential Game Changer

By UCILIA WANG Sept. 28, 2014

A class of compounds first uncovered in the Ural Mountains more than a century ago is now a rock star in the world of solar-energy research.

Meet perovskite, the building block for materials that, as a group, have posted unprecedented gains in their solar-energy efficiency—the percentage of sunlight converted into electricity. In the lab, scientists experimenting with perovskite-based materials of different compositions have recently achieved a jump in efficiency to 20%, from around 10% just two years ago.

That is still lower than the most efficient silicon-based cells on the market— SunPower Corp. makes cells that are 24% efficient.

But because of perovskite's rapid increases in efficiency, researchers think it could be used to make cells that are at least as efficient as those fashioned from silicon, but at a much lower cost.

Game Changer?

If it pans out that way, researchers say, perovskite could play a crucial role in the future of solar power.

It can be made into stand-alone solar cells or layered on top of silicon solar cells to boost energy production by grabbing light from a part of the spectrum that silicon can't capture.

"Perovskite does seem to promise to be a high-efficient, low-cost material," says Jao van de Lagemaat, center director for chemistry and nanoscience at the U.S. Department of Energy's National Renewable Energy Laboratory in Colorado, which is doing perovskite research for an undisclosed chemical company.

"This might be one of the materials that is going to change the game," he says.

Cost Advantages

Perovskite was named after the Russian mineralogist Lev Perovski when it was first found in 1839. The mineral unearthed then was calcium titanium oxide. But the term perovskite today is used to describe any compound that shares the same crystalline structure as the original.

Why perovskite works so well for solar cells is a mystery. "There has never been this technology that grows in efficiency number so quickly," says Mr. van de Lagemaat. "People are intrigued by why does it work and how can it be so efficient. It's sort of an enigma."

One advantage of perovskite is that it can be made of common metals and industrial chemicals, instead of the expensive raw materials used in other silicon substitutes. Also, perovskite-based materials could be used to print photovoltaic electronics directly onto glass or other materials, which would be cheaper than more-complex methods for producing thin-film solar cells.

Getting It to Market

The U.K.-based startup Oxford Photovoltaics is one of the leading companies working on perovskite. Its chief scientific officer, Henry Snaith, led one of the two teams credited with changing the designs of perovskite solar cells to increase their efficiency more quickly.

Oxford plans to license its recipe for a liquid form of perovskite to a chemical company and the process for using that liquid to make solar cells to glassmakers or cell makers, says Chris Case, chief technology officer of Oxford. The company expects products based on its technology to hit the market by 2017.

But others are more cautious, pointing out that developers still have to overcome some hurdles to bring perovskite to market.

They have yet to prove that perovskite-based materials could last as long as silicon solar cells.

They also have to figure out how to protect perovskite materials against moisture, which erodes their performance significantly.

"Perovskites are still in an infant state and may easily take more than five years before they reach maturity," says Homer Antoniadis, global technology director of DuPont Co. 's solar business. more

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