Science

Carbon nanotube solar cells point to possible transparent solar window future

Carbon nanotube solar cells po...
A researcher from Adelaide's Flinders University has developed a prototype solar cell that uses a layer of transparent carbon nanotubes sandwiched between conductive glass to collect solar energy
A researcher from Adelaide's Flinders University has developed a prototype solar cell that uses a layer of transparent carbon nanotubes sandwiched between conductive glass to collect solar energy
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A researcher from Adelaide's Flinders University has developed a prototype solar cell that uses a layer of transparent carbon nanotubes sandwiched between conductive glass to collect solar energy
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A researcher from Adelaide's Flinders University has developed a prototype solar cell that uses a layer of transparent carbon nanotubes sandwiched between conductive glass to collect solar energy
The trade off between transparency and the ability to harvest light means that even the best cells in the lab are only just approaching one percent efficiency
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The trade off between transparency and the ability to harvest light means that even the best cells in the lab are only just approaching one percent efficiency
Dr Mark Bissett working on the carbon nanotube solar cell
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Dr Mark Bissett working on the carbon nanotube solar cell
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Imagine if every window of the 828-meter (2,717-foot) high Burj Khalifa in Dubai was capable of generating electricity just like a PV panel. That's the promise of solar window technology like the RSi and Sphelar cells systems. Rather than using costly silicon for window-based collection of solar energy, Dr Mark Bissett proposes using a very thin layer of carbon nanotubes instead.

As part of his PhD at the Flinders University School of Chemical and Physical Sciences, Dr Bissett has developed a proof of concept prototype solar cell that is made up of two sheets of electrically-conductive glass with a layer of functionalized, single-walled carbon nanotubes sandwiched between them. As the nanotube layer is only between 100 - 200nm thick and the two sheets of glass are just 60µm apart, the cell remains transparent - letting some natural light flow through while also collecting energy from the sun.

"When light shines on the cell, electrons are generated within the carbon nanotubes and these can be used to power electrical devices," said Dr Bissett. "It's basically like tinting the windows except they're able to produce electricity, and considering office buildings don't have a lot of roof space for solar panels, it makes sense to utilize the many windows they do have instead."

Dr Mark Bissett working on the carbon nanotube solar cell
Dr Mark Bissett working on the carbon nanotube solar cell

Unfortunately, the cells have yet to be tested outside of the laboratory and work is still needed to improve the efficiency of the technology before being scaled up to an industrial level. Dr Bissett told us that the trade-off between transparency and the ability to harvest light means that even the best cells in the lab are only just approaching 1% efficiency. There is a way around this, but it comes at a cost.

"Basically by decreasing transparency you can increase efficiency," explained Dr Bissett. "In comparison, other new solar cell technologies like dye-sensitized solar cells are close to 10% and silicon solar cells tend to be around the 20% mark, depending on the exact technology used to produce them. So work is still needed on increasing the efficiency of our designs to make them competitive, but it is still early days for this technology with many possible research avenues to pursue."

Dr Bissett has also successfully demonstrated that the carbon nanotube layer can be spray-coated onto glass, which would allow for larger areas of glass substrate to be functionalized. The next step in the development process is to test the technology in the real world. He believes that if all goes to plan, the new technology could be on the market within the next ten years.

"This research is still being pursued by the research group I worked with at Flinders University with Professor Joe Shapter," he said. "There is also work being undertaken to produce flexible solar cells based on graphene, these are of interest for integration into fabrics."

Meanwhile Dr Bissett is currently undertaking a post-doctorate at Kyushu University, Japan.

Source: Flinders University

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10 comments
10 comments
Carlos Grados
This is an exciting technology! Could these nanotubes be sprayed on anything and still produce electricity?
Gadgeteer
More tantalizing but ultimately technology that we'll never see in the market, in all probability. We've been promised transparent photovoltaic windows for at least 20 years now.
Nathan Jeffree
@ Carlos..... That's a good question, one I would like to know the answer to as well. If so, the possibilities would be endless :-)
DR.ZARKOF
The most profitable line of research for these scientists to follow would be to try to restrict energy absorbtion and conversion to portions of the spectrum outside the range of visible light. Not only would this eliminate the trade off between efficiency and transparency but would help to solve other problems. Buildings with large window surfaces suffer from overheating in direct sunlight due to infra-red light and fading of carpets and drapes due to ultra-violet light. A product that could solve both of these problems while producing electricity would sell itself.
usugo
so instead of using costly silicon, he is using very very expensive carbon nanotubes! That sounds "smart"!
Dan79
ugosugo, do you think the price of silicon is going to lower anytime soon? Further more do you think the price of carbon nanotubes is going to change anytime soon? Sometimes you have to push on with the technology even if it is not feasible today....
Andrew B Spencer
A very good concept and very good responses,the answers are all around us, the future is closer than people think, it is all about the people, and the willingness of people working together.Some time people and their thoughts are ahead of there time.But in this case the time should be now. And the answers are here today.
Iosif Olimpiu
We hope to use this technology as soon as it's possible. I was wondering why this ideea doesn't exist yet, but there may be some economical facts, we never know. Thank you, Japan!
wiarus2000
I think XSUNX INC. does it already
Mark Keller
It would be great if this could be sprayed on any kind of surface and produce electricity. Would love to see this in cars, home exteriors and roofs.