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Friday, July 13, 2007 Record Efficiency for Plastic Solar CellsResearchers find a new way to make cheap and flexible photovoltaic cells. By Peter Fairley
A new process for printing plastic solar cells boosts the power generated by the flexible and cheap form of photovoltaics. Initial solar cells made with the technique can, according to a report in today's issue of Science, capture solar energy with an efficiency of 6.5 percent--a new power record for photovoltaics that employ conductive plastics to generate electricity from sunlight. Most photovoltaics are made from conventional inorganic semiconductors. The new process stacks multiple polymer layers within a single photovoltaic device to produce a "tandem" cell. Alan Heeger, who won the 2000 Nobel Prize for his codiscovery of electrically conducting polymers, and his colleagues at the University of California, Santa Barbara (UCSB), created the process with a group from South Korea's Gwangju Institute of Science and Technology. Heeger says that the tandem architecture offers plenty of room for further improvement--enough to eventually make plastic solar cells practical in rooftop solar panels. "We see a pathway here toward even higher efficiencies," he says. "We can do significantly better than 6.5 percent in the near future." Tandem cells, commonly employed in conventional solar panels, increase power output in two ways. The semiconductors in the different layers can be optimized to capture different bands of light, thus enabling the tandem device to absorb a broader spectrum of sunlight. And the multiple layers boost the voltage of the tandem device, yielding more power from every photon absorbed. "You do a better job of light harvesting and a better job of utilizing the photon energy," explains Heeger. Until now, however, the tandem architecture spoiled plastic photovoltaics such as Heeger's, which are "printed" by spraying solutions of conductive plastics and other materials onto a plastic film. Layers of different plastics sprayed on top tended to mix, degrading rather than enhancing power output. Heeger and his colleagues beat the mixing problem by finding an effective spray-on separator to keep the layers in place. The bottom cell is filled with a proprietary polymer first disclosed last year by plastic PV developer Konarka Technologies, based in Lowell, MA, which Heeger cofounded and for which he serves as chief scientist. The polymer (a derivative of polythiophene) absorbs both infrared and ultraviolet light. Next comes a titanium-suboxide layer, which seals in the bottom cell, provides a foundation for building the top layer, and, as it's a metal, efficiently carries away the charged electrons generated in both layers. Finally, the top layer sports a different type of conducting polymer that absorbs mostly blue and green light. Heeger expects further efficiency strides as device developers gain experience with the cell's new materials. For example, in May, the UCSB researchers reported a processing tweak that doubles the power output of single cells made with Konarka's new polythiophene polymer. Heeger says that the processing trick was not used in the tandem cell. |
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Cheaper, More Efficient Solar Cells
03/21/2007
Comments
nekote on 07/13/2007 at 8:12 AM
115
Made out of "plastic" ought to be "cheap".
How much is it going to cost, to produce how many net KWH for end users?
How durable will these solar cells be?
Will they need to be replaced every year?
3 years? 5? 10?
nick47g on 07/13/2007 at 2:30 PM
17
Even at 5-6%, if this can be spooled out of a factory at a few bucks a square foot it can be a good thing.
Nick G
South Dartmouth MA
advill on 07/14/2007 at 8:08 AM
11
We are 10 years from a reliable open (civilian) product.
country mouse on 07/16/2007 at 12:02 PM
1
fredwright on 07/16/2007 at 5:10 PM
1
martinaatayo on 07/23/2007 at 2:21 AM
31
of any product development.
In this context, efficiency in output, very uncertain, in my perception, but in production cost,endproduct risk
factors and safety, likely favorable.
lonestar on 10/15/2007 at 11:14 PM
1
The real cost of the power is not relevant. There is special "Greenie Math" you must learn. In "Greenie Math" never worry about real cost. You must support insane funding of greenie scams, and government subsidies fall from the sky (from the Tooth Fairy) without impacting anything else in society (such as medical care and money to send kids to college).
So what if your solar electricity costs 50 cents a KWH, suck it up, laws must force you to buy it. Turn off your air conditioner and lights and send your kids off to the recycling center at age 18, there are no other industrial jobs with power at half a buck.
ablamp on 07/26/2007 at 8:40 AM
5
http://www.ablamp.com
mlado on 08/09/2007 at 12:59 PM
1
They raised a pile of dough, couldn't do it and bought an Austrian plastic solar startup and acquired Siemens ip with plastic and fullerenes.
They still couldn't do it and they raised another pile of dough and shifted focus to Quantum Dots embedded in a polythiophene.
Raised another pile of dough and now are making more promises.
What's next with these bozos? Betchya they're going to claim power from moonlight and raise another pile of dough.
Siphon on 08/21/2007 at 5:25 AM
93
badmoonryzn on 04/18/2008 at 2:33 AM
1
It has been two years now and they are still dragging their feet. I guess their two million hasn't run out yet. Oh yea, check out their web site contact information. The only one that send you to a form is if you want to send them money the rest run you around in circles or give you the don’t call us we’ll call you message. They have had plenty of time to get a product to market and I wonder if it is as great as they say it is big business is likeky going to do everything they can to stop production of the product because they would loose money if the normal Joe had the ability to generate cheap electricity he wouldn’t need to buy near as much power from the grid and many would be selling their excess back to the power companies. At 20 dollars for a 50 watt panel or even better print your own on your ink jet printer for 10 cents a watt the whole economy would be effected. Why we would have electric cars anywhere there was sun.
Imagine the reality of this product, why I could afford to power my 2000 sq ft house with solar panels and a battery system for under 1500 dollars. It would pay for it’s self in less than a year. Nope, I seriously doubt it is going to happen any time soon. Even if it does work there is no way big business will ever let Joe average get his hands on anything like that in this millennium there is just to much at risk in big business’s pocketbook!
It nice to dream though.
badmoon
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1
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