New technique offers spray-on solar power

Posted Dec 8, 2014 by James Walker
A team has created a new way to harvest solar power by spraying solar cells onto flexible surfaces, representing a step towards easy and cheap solar electricity by simply spraying a surface.
Solar power in Germany.
Solar power in Germany.
Rainer Lippert
Created by Illan Kramer and colleagues, the technique involves laying materials onto a surface at a one-atom thickness each time. Called sprayLD, the name is a play on the term "ALD" which describes the process used: atomic layer deposition.
The device was created from affordable, readily available parts. The main nozzle is used in steel factories to spray water mists to cool the steel with and the only other main parts are a few air brushes, sourced from art stores. Kamer said of the solution “This is something you can build in a Junkyard Wars fashion, which is basically how we did it. We think of this as a no-compromise solution for shifting from batch processing to roll-to-roll."
The design works by spraying miniscule particles of a light-sensitive material onto a surface. The material is known as colloidal quantum dots (CQDs) and could previously be used only in batch processing on assembly lines where it is slow and expensive to achieve. This development is important because it indicates that the CQDs can be used on flexible materials without major loss in solar-cell efficiency by directly spraying a liquid containing the CQDs onto the material.
The IBM Canada Research and Development Centre and the King Abdullah University of Science and Technology went on to support Kramer and his colleagues as they used the IBM BlueGeneQ supercomputer to explain how and why the spraying method works so well. The results are published in the ACS Nano journal. Kramer's supervisor at the University of Toronto said “We were thrilled when this attractively manufacturable spray-coating process also led to superior performance devices showing improved control and purity.”
Kramer himself, a post-doctoral fellow of the University of Toronto and IBM Canada Research & Development Centre, said of the findings “My dream is that one day you’ll have two technicians with Ghostbusters backpacks come to your house and spray your roof [to harness solar electricity]."
If the method continues to prove successful in further trials and industrial deployment, spraying CQDs could soon become a wide-spread method of gaining power for devices as even oddly-shaped units could be sprayed with the light-sensitive cells. A car roof sprayed with CQDs would be able to produce enough energy to power three 100-watt light bulbs, so it is easy to see how useful the technique could be in the future.