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First true “all-carbon” solar cell developed


October 31, 2012

The all-carbon solar cell consists of a photoactive layer, made of carbon nanotubes and bu...

The all-carbon solar cell consists of a photoactive layer, made of carbon nanotubes and buckyballs, sandwiched between two electrodes made of single-walled carbon nanotubes and graphene (Photo: Mark Shwartz)

Researchers at Stanford University have developed an experimental solar cell made entirely of carbon. In addition to providing a promising alternative to the increasingly expensive materials used in traditional solar cells, the thin film prototype is made of carbon materials that can be coated onto surfaces from a solution, cutting manufacturing costs and offering the potential for coating flexible solar cells onto buildings and car windows.

Stanford graduate student Michael Vosgueritchian, who is co-lead author of the study, says that while other groups have previously claimed to have developed all-carbon solar cells, the “all-carbon” component of these other cells was limited to the middle active layer. In comparison, the entirety of the Stanford solar cell, including the electrodes, is made from carbon materials.

In place of the expensive conductive metals, such as silver and indium tin oxide (ITO), used in the electrodes of typical silicon solar cells, the Stanford researchers, led by Professor Zhanan Bao, used graphene and single-walled carbon nanotubes, which boast impressive electrical conductivity and light-absorption properties.

Like the “all-carbon’ solar cell developed by MIT that we looked at earlier this year, the active layer of the Stanford team’s solar cell is made from a material containing carbon nanotubes and “buckyballs,” which are soccer ball-shaped molecules with carbon atoms at each vertex.

MIT’s proof of concept devices achieved an efficiency of only 0.1 percent and Stanford’s prototype can only claim a laboratory efficiency of less than one percent, which is far short of the efficiencies seen in conventional silicon solar cells. However, Bao says, “with better materials and better processing techniques, we expect that the efficiency will go up quite dramatically."

The main problem is that both the MIT and Stanford carbon-based prototype solar cells primarily absorb light in the near-infrared part of the spectrum. To improve efficiency, the Stanford team is experimenting with carbon nanomaterials that can absorb more light in a broader range of wavelengths, including the visible spectrum.

They are also looking at ways to enhance the smoothness of the solar cell as, “roughness can short-circuit the device and make it hard to collect the current,” says Bao. "We have to figure out how to make each layer very smooth by stacking the nanomaterials really well."

Despite the inefficiencies compared to traditional solar cells, there are some conditions in which carbon solar cells can outperform conventional devices. Since materials made from carbon remain stable in air temperatures of almost 1,100° F (593° C), they can perform in extreme conditions.

"We believe that all-carbon solar cells could be used in extreme environments, such as at high temperatures or at high physical stress," says Vosgueritchian. "But obviously we want the highest efficiency possible and are working on ways to improve our device."

The team’s work is published in the journal ACS Nano.

Source: Stanford University

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag.   All articles by Darren Quick

Another Useless Technology release with unrealized potential, capable or not. By the time the technology is refined, it will be no longer relevant to society.

Raymond Johnson
31st October, 2012 @ 11:47 pm PDT

Wow, pessimistic much. With an attitude like yours there would never be any scientific development.

James Thistlethwaite
1st November, 2012 @ 06:37 am PDT

All of this wonderful tech developed at American universities subsidies by American tax dollars directly and indirectly ("you didn't build that") and yet when its developed, the solar panels will be produced in Asia while the US is trillions in debt.

Rann Xeroxx
1st November, 2012 @ 06:55 am PDT

I am always excited about the possibility of SOMEONE producing solar cells that are; Effective, efficient, and LOW in cost (the cost being a very big factor).... Then if systems were built cheap enough, can you imagine how wonderful OUR COUNTRY could be if everyone could cover their roofs with them and produce electric all day long... Yes, it might not be enough to provide ALL of the power needed for each home, but even if it amounted to half. WHAT A SAVING! Cut your electric bills in half, cut the consumption of fossil fuels for electric generation in half, (and maybe cutting the cost of electric in manufacturing of all sorts of items in half...) But, currently, who can afford $15-20K to outfit your home? They need to get it down to less than $2K per home.... And, we have LOADS of carbon....COAL!

1st November, 2012 @ 10:04 am PDT

Observer you are talking about prices several yrs ago. You can now buy solar panels for $1k/kw making them on a home, building far cheaper than utility power. among other sources. Installing them costs more than the panels do now.

Next panel are rather cheap now so the cheaper material especially some that are 0.01% of the power eff of present ones is a bad joke. Once they hit at least 10% they won't be anything as installation costs would be higher as they take so much more room that the 20% or so eff panels now.

As for an eff home a system costing $6k of 2.5kw installed could make the power needed and pay for itself in 4 yrs and almost free power for another 20 yrs. Do the math.

1st November, 2012 @ 12:19 pm PDT

Just to add to jerryd / Observer101-

Be sure and look for the incentives too. Right now you get 30% federal tax credit for solar.

Many states, counties, utility companies are also providing incentives. You just have to look and get it done as soon as they offer something.

For example - A couple weeks ago in Florida (Florida power & light) offered $2. a watt rebate for setting up solar, systems up to 10kw. The rebate alone could pay for the system itself, depending on the installation cost of it.

If nothing available right now, look into microinverter systems that you can start small and expand later (google search will get you there).

1st November, 2012 @ 07:18 pm PDT

Solar energy has always been a waste. We waste good scientist, billions of dollars and public will on a concept that has already been perfected. Sorry but the best way to produce energy from the sun is through biomass. Sorry PV and other solar technology have all been busts. I am completely in favor of solar hot water heating, but making electricity from solar is moronic.

Michael Mantion
1st November, 2012 @ 11:00 pm PDT

@ Rann Xeroxx

Despite being first developed in the US, it is still made who a Chinese.

Also, American tax dollars is pretty much all borrowed money.

And why would you bother complaining? It's the big conglomerates that will reap the profit no matter where this thing is built anyway.

Savin Nay Wangtal
2nd November, 2012 @ 08:02 am PDT

Wow! This is awesome! An "all carbon" solar cell is awesome! Thanks for sharing this interesting article!

Darcy Hubbert
7th November, 2012 @ 04:32 pm PST
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