Environment

New method could lead to cheap, spray-on solar power for flexible surfaces

New method could lead to cheap...
The SprayLD system developed by University of Toronto researchers can spray colloidal quantum dots onto flexible surfaces
The SprayLD system developed by University of Toronto researchers can spray colloidal quantum dots onto flexible surfaces
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The SprayLD system developed by University of Toronto researchers can spray colloidal quantum dots onto flexible surfaces
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The SprayLD system developed by University of Toronto researchers can spray colloidal quantum dots onto flexible surfaces
Illan Kramer, one of the university's post-doctoral fellows, has developed an instrument where colloidal quantum dots can be sprayed onto flexible surfaces such as film or plastic
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Illan Kramer, one of the university's post-doctoral fellows, has developed an instrument where colloidal quantum dots can be sprayed onto flexible surfaces such as film or plastic

Spray-on cells hold considerable promise for reducing the manufacturing costs of solar power. Within this field, colloidal quantum dots (CQD) have also been the focus of a number if research efforts, as they have the potential to soak up a wider range of the solar spectrum. Scientists at the University of Toronto have been aboard the quantum dot train for some time now and their latest breakthrough involves a new method for spraying solar cells onto flexible surfaces, a development that could one day see them coat anything from bicycle helmets to outdoor furniture.

In such spray on solar cells, quantum dots would act as the absorbing photovoltaic material. Because they have a band gap that can be tuned by altering the size of their nanoparticles, they can be made to soak up different parts of the solar spectrum. This could prove particularly valuable if they were to be used in multi-junction solar cells, where dots small and large could sit alongside each other to widen the cells' energy harvesting potential.

Earlier this year, University of Toronto scientists developed a new kind of CQD that doesn't bind with oxygen atoms, a problem that causes some dots to forgo their electrons and become useless. The researchers recorded a solar efficiency of eight percent, much less than that of commercially available panels, but were optimistic about the dot's potential to power new kinds of devices.

The scientists say that until now, integrating CQDs into materials has only been possible through batch processing, a procedure that is inefficient and expensive. But Illan Kramer, one of the university's post-doctoral fellows, has developed an instrument where the dots can be sprayed onto flexible surfaces such as film or plastic, an advance that could make the process a lot simpler.

"My dream is that one day you’ll have two technicians with Ghostbusters backpacks come to your house and spray your roof,” says Kramer.

Printing light-sensitive CQDs onto thin and bendable materials could theoretically see them applied to just about any irregular surface, as well making cells cheaper and easier to manufacture. According to the researchers, covering the roof of a car in CQD-laden film would generate power enough for three 100 W light bulbs.

Kramer's system is dubbed SprayLD and is built from inexpensive, readily available components. Comprising standard air brushes and a spray nozzle used to cool steel in a mill, Kramer's contraption sprays the CQDs onto the film-like materials, and reportedly does so without incurring major losses in performance of the cells. The researchers tell us they achieved an efficiency of 7.2 percent.

“As quantum dot solar technology advances rapidly in performance, it’s important to determine how to scale them and make this new class of solar technologies manufacturable,” said Professor Ted Sargent, Kramer's supervisor and vice dean, research at the University's Faculty of Applied Science & Engineering. “We were thrilled when this attractively manufacturable spray-coating process also led to superior performance devices showing improved control and purity.”

Kramer's research has been published across a series of journal articles, initially in Applied Physics Letters, then in Advanced Materials and most recently in ACS Nano.

You can see a video demonstration of the SprayLD system below.

Source: University of Toronto

sprayLD - New technique offers spray-on power

9 comments
Ed Pope
These are exciting times, I just wish that many of these innovations would come out quicker to improve our home energy capabilities.
Future3000
Good work Canada! 8% is amazing! Normal spray-on PV Systems effectiveness only is 1,5 - 2,5 %! Please hurry up, make it very cheap, fill it into spray tincans, so everybody can electrify the house,car, bike, skateboard, trailer home, boat by him/herself! If you will start it at Kickstarter, i will buy a lot of these Spray-cans.
DonGateley
“We were thrilled when this attractively manufacturable spray-coating process also led to superior performance devices showing improved control and purity.”
What superior performance might that be? Watt's per unit area would be a cool spec to include in the article.
David Leithauser
Pet peeve department: "generate power enough for three 100 W light bulbs." That is 300 watts. Why can't authors just say that instead of bringing in hypothetical light bulbs? This was in reference to covering the top of a car. Who is going to run 3 100 watt light bulbs in a car?
On a more serious note, if they could get 300 watts of solar energy off the top of a car, it seems to me that this would be a great way to range extend an electric car. Drive your electric car to work and park it in the sun all day to charge up your batteries, and you get X additional miles of travel to get home. Could be useful for cars that do not quite make the round trip to the office and back on a charge. For long drives (maybe electric tucks?), driving cross country in the day with such solar panels on top your car could reduce the number of stops you need to make to recharge.
Anyway, this is yet another hopeful improvement on the way to getting us off fossil fuels in time to prevent disastrous climate disruption. Being able to cheaply spray solar panels on just about every surface of your house that faces the sun will bring us more solar power.
ajl12no
8% efficiency is crap, put bluntly...there is a molecular solar liquid being tested by NASA that has a 40%+ efficiency already and rising. Quantum dots are barking up the wrong tree. Back to the drawing board for the Canadians...sorry. ;-)
William Carr
@ajl12no
You did know that Quantum Dot solar cells hold the record for solar efficiency?
It’s the method here that needs improving, not the material.
Dawn Fitch
Thank you for airing the ideas. Very interesting ideas.
marbaron
I have heard about simpe way of some kind of solar cell production by electrodeposition method: https://www.researchgate.net/publication/272091856_X-ray_solar_cell_based_on_carbon-metal_junction