Published on December 14th, 2019 | by Tina Casey0
COP25 Got You Down? “Impossible” Solar Cells To The Rescue!
December 14th, 2019 by Tina Casey
While the folks over at the COP25 climate talks in Madrid are busy getting nowhere on climate action, a team of US scientists has come up with a way to cut the cost of manufacturing ultra-efficient solar cells. The new “impossible” solar cell brings outer space technology down to earth, where it could help accelerate the trend away from fossil fuels. It’s not a laboratory fever dream, either. The team includes a US company that already has the secret sauce in hand.
Get Ready For The Impossible Solar Cell Of The Future
Oh, the irony. All fingers point to the US as one of the major reasons why the COP25 talks have stalled (shocker!), but the US is also one of the main reasons why the renewable energy revolution is poised to accelerate, and fast.
The last good news about photovoltaic research in the US comes from a team at the National Renewable Energy Laboratory in Colorado.
Working with a team from the North Carolina firm Kyma Technologies, the researchers took on the problem of how to integrate aluminum into a hydride vapor phase epitaxy (HVPE) reactor, in order to “grow” two semiconductors, aluminum indium phosphide (AlInP) and aluminum gallium indium phosphide (AlGaInP).
Got all that? Good! The basic idea is that reactor-based manufacturing provides for a relatively quick, low cost way to produce new materials for solar cells.
The problem, up to now, is coaxing a reactor into producing these two particular ultra-efficient materials, AlInP and AlGaInP.
The researchers were told that was impossible. Well, they sure showed whoever told them that.
How To Make An Impossible Solar Cell
As for how it works, here’s the rundown from the lab. Oh wait, never mind. That’s too complicated. The key thing to keep in mind is that the modern way to “grow” solar cells is to vaporize materials and deposit the vapor on a thin slab of some other material. The slab (aka “substrate” in fancyspeak) can be re-used again and again to grow more solar cells.
The NREL-Kyma researchers used a new kind of multi-chamber reactor, which speeds up the process considerably.
According to the lab, a basic solar cell takes about an hour or more to produce in a conventional reactor. The multi-chamber reactor cuts that time to less than a minute.
Since time is money, that’s a pretty neat trick. However, the researchers were still stuck at the part about introducing aluminum into the mix.
After investing a considerable amount of time and effort in validating the process, the team’s next step was to introduce the secret sauce from Kyma.
As described by the lab, Kyma has developed a method for producing a “unique aluminum-containing molecule” that can be slipped into the multi-chamber reactor.
For all the particulars, check out the team’s article newly published in the journal ACS Applied Energy Materials under the title, “Growth of AlGaAs, AlInP, and AlGaInP by Hydride Vapor Phase Epitaxy.”
Shorter version: this is a relatively inexpensive pathway for fabricating the kind of ultra-efficient III-V solar cells that are currently available only for space applications because they are too expensive for the Earth-bound market.
By the numbers: according to NREL, III-V solar cells produced through the conventional process have reached a record efficiency of 29.1%. The new process has the potential to produce solar cells on par with them, only much cheaper.
Move Over, Natural Gas
With coal on the way out for new utility-scale power generation in the US, natural gas is the next fossil domino to fall. The new NREL-Kyma breakthrough should start making those natural gas stakeholders plenty nervous.
“Now we’ve shown a pathway to the same efficiency that’s the same as the other guys, but with a cheaper technique,” explained Aaron J. Ptak, a senior scientist at the National Center for Photovoltaics at NREL. “Before, we were somewhat less efficient but cheaper. Now there’s the possibility of being exactly as efficient and cheaper.”
Think of it as the Impossible Burger for renewable energy and you’re on the right track.
As for when you can expect those new III-V solar cells on your rooftop, that’s a good question. CleanTechnica is reaching out to Kyma for some insights on that, so stay tuned.
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Photo: “Sample aluminum III-V solar cells, grown using HVPE, are shown as Alx(Ga1-x)0.5In0.5P thin films after removing the GaAs substrate bonded to a glass handle for transmission measurements. The difference in color is due to the difference in the composition of Al and Ga. Specifically, the yellow samples are AlInP (no Ga) and the orange samples are AlGaInP. Photo by Dennis Schroeder, NREL.”
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