'Nanocoax' solves solar cell 'thick and thin' dilemma

Jun 07, 2010
Boston College researchers report developing a "nanocoax" technology that can support a highly efficient thin film solar cell. This image shows a cross section of an array of nanocoax structures, which prove to be thick enough to absorb a sufficient amount of light, yet thin enough to extract current with increased efficiency, the researchers report in the journal Physica Status Solidi. Credit: Boston College

A nano-scale solar cell inspired by the coaxial cable offers greater efficiency than any previously designed nanotech thin film solar cell by resolving the "thick and thin" challenge inherent to capturing light and extracting current for solar power, Boston College researchers report in the current online edition of the journal Physica Status Solidi.

The quest for high power conversion efficiency in most thin film has been hampered by competing optical and electronic constraints. A cell must be thick enough to collect a sufficient amount of light, yet it needs to be thin enough to extract current.

Physicists at Boston College found a way to resolve the "thick & thin" challenge through a nanoscale solar architecture based on the coaxial cable, a radio technology concept that dates back to the first trans-Atlantic communications lines laid in the mid 1800s.

"Many groups around the world are working on nanowire-type solar cells, most using crystalline semiconductors," said co-author Michael Naughton, a professor of physics at Boston College. "This nanocoax cell architecture, on the other hand, does not require crystalline materials, and therefore offers promise for lower-cost solar power with ultrathin absorbers. With continued optimization, efficiencies beyond anything achieved in conventional planar architectures may be possible, while using smaller quantities of less costly material."

Optically, the so-called nanocoax stands thick enough to capture light, yet its architecture makes it thin enough to allow a more efficient extraction of current, the researchers report in PSS's Rapid Research Letters. This makes the nanocoax, invented at Boston College in 2005 and patented last year, a new platform for low cost, high efficiency .

Constructed with amorphous silicon, the nanocoax cells yielded power conversion efficiency in excess of 8 percent, which is higher than any nanostructured thin film solar cell to date, the team reported.

The ultra-thin nature of the cells reduces the Staebler-Wronski light-induced degradation effect, a major problem with conventional solar cells of this type, according to the team.

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jonnyboy
Jun 07, 2010
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ecdfan
1 / 5 (2) Jun 08, 2010
There is a spelling mistake in this article. It should be nanohoax, not nanocoax.

The physicists at Boston College are simply lying - they are wrong to assume that the physorg.com readers are clueless. First Solar, the world's largest cell manufacturer, makes nano thin-film cells that are more than 11.2% efficient (way above that "record" 8%) and cost just 81c per Watt to make.

Oh, and yes, the First Solar cells don't suffer from any Staebler-Wronski degradation effect.
SmarterThanYou
3 / 5 (2) Jun 11, 2010
"ECDman" is correct about one thing. Physorg.com readers are not clueless.

I am sure I am not the only physorg reader to find it interesting that "ECDman" is promoting FirstSolar's CdTe inexpensive cells, a fundamentally different technology from the technology in the news article, rather than the Unisolar (a subsidiary of ECD) "same technology" $2/W a-Si:/SiGe tandem cells which do suffer from Staebler-Wronski degradation.

The claim in the news article that 8% represents a higher reported efficiency than any nanostructured thin film solar cell to date seems about right. The literature (mostly Nature & Science) is littered with papers where people have taken perfectly good thin film solar cell technology and degraded the performance down to a few percent through the use of nanostructures.

Don't even start on how many nanostructure solar cell schemes one sees that have no hope of ever being scalable for production.
OldCurmudgeon
5 / 5 (1) Jun 25, 2010
First post displays the Dunning–Kruger Effect.

1. First Solar (FS) is not the world's largest cell manufacturer. 85% of the market for solar cells (in wattage) is dominated by single crystal and polycrystalline SILICON solar cells, which FS does not make.
2. FS calls itself the leader, just like every solar company. FS’s market is part of the 15% of the market that is not single crystal/poly Si, so even dominating that market would still make them a niche player pumping out inefficient (compared to xtal-Si) modules.
3. FS’s CdTe contains toxic Cd. In the EU, manufacturers are responsible for the costs of recovery of toxics in their products. Si panels have no toxics in them. FS’s Cd recovery obligations are daunting & expensive.
4. All thin films cells use "nano thin-films". The definition of "thin film" is films under 1 um thick. Amorphous silicon single junction cells are ~500nm thick. This is as opposed to thick film solar cells like CIGS, which are many microns in thickness.