15 February 2012, 12:58 BST
The most organic solar cell possible is a leaf, but photosynthesis is ridiculously difficult to reproduce. That hasn't stopped a number of researchers from trying, and this week an American company from Illinois has set the new efficiency record for an organic solar cell, or OPV.
Polyera, based in Skokie, Illinois (a suburb of Chicago), announced 9.1% efficiency in the lab, and the results were confirmed by Newport Corporation of Irvine, California. Given some of the previous efficiency levels reported for solar cells (current records are around 17% for some types of relatively cheap solar cells, somewhere in the 25% range for others, over 30% for high concentrating photovoltaic (HCPV) modules, and over 43% for concentrated photovoltaic cells), this may not seem like much. However, commercial viability is based on a mixture of cost and efficiency and the tipping point for a mass-market launch of organic solar cells is reportedly 10%. So, Polyera has put OPVs super close to actual commercialization.
Brendan Florez, deputy general director of Polyera, spoke briefly to Renewables International on the difficulties of going to mass production, and why 9% isn't good enough:
"But it's hard to say how much efficiency will drop in mass production. After all, the actual manufacturer will determine the outcome, and that won't be us. Up to now, we have seen efficiencies drop by 4 to 6 percentage points in industrial production. Of course, we hope that our material is more robust."
The system Polyera is using is a new type of layering system-conductive polymer is applied to a substrate (here indium and tin oxide), followed by the photoactive polymer and finally the front contact. Polyera's CTO, Antonio Faccetto, said that by focusing on the chemical side of things, the company found new ways of combining existing components with better conversion efficiency than before.
Recombining the materials didn't just increase conversion efficiency; the new solar cell is also supposed to be flexible and super light (excellent for transportation around the country or the world). While that will probably help installation, Polyera will be happier if the cells can be made inexpensively and last forever, at least one of which may be possible.
Another oddity Polyera discovered was that the thickness of the photoactive layers had no effect on efficiency. The lack of precision needed plus the ability to manufacture the material on inexpensive foils could simplify the production process considerably, which would seem to imply low production costs right off the bat.
However, without a manufacturer-and Polyera hasn't found one yet-no specific numbers can be generated. The company is currently making samples to try and find a commercial partner or two.
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Source: Renewables International | Image: Wikimedia Commons
Source: Clean Technica