Researchers at the University of Toronto have unveiled a cheap, fast spray-on solar cell process that could enable the creation of solar arrays using the most modest of manufacturing methods. Even better, with the cells ‘printed’ onto flexible material, they could turn anything from airplane wings to your patio furniture into a solar power plant.
The research was led by University of Toronto researcher Illan Kramer, who calls the system sprayLD. Much as with many previous spray-on solar designs, spray LD utilizes colloidal quantum dots (CQD). CQD are tiny, light-sensitive dots—invisible to the naked eye—that can act as an absorbing photovoltaic material. The technology has long held promise, but the process of incorporating light-sensitive CQD’s onto surfaces has been expensive, slow and laborious.
What Kramer and his colleagues have done is to invent an entirely new, cheap, efficient technique for creating solar cells using CQD. They based the technique on a newspaper-printing process, and explain “SprayLD blasts a liquid containing CQDs directly onto flexible surfaces, such as film or plastic… by applying ink onto a roll of paper. This roll-to-roll coating method makes incorporating solar cells into existing manufacturing processes much simpler.”
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As for their prototype, the team admits that it may look “more like junkyard wars than high-tech,” but that’s because it was made entirely from affordable, readily available parts; U of T explains “[Kramer] sourced a spray nozzle used in steel mills to cool steel with a fine mist of water, and a few regular air brushes from an art store.”
Which perhaps makes it all the more surprising that this technique does not appear to cause any major drop offs in efficiency. However, efficiency is still a major consideration with spray-on solar. The sprayLD system converts about 8.1% of sunlight to power, as opposed to 15-20% for standard rooftop solar arrays. But, speaking to Co.Exist, Kramer explained that while he is working on boosting sprayLD’s efficiency “we think of ourselves as operating in a slightly different paradigm, where we don’t have to be quite as efficient because we’re so much less expensive.”
And in the long run, Kramer explains: “My dream is that one day you’ll have two technicians with Ghostbusters backpacks come to your house and spray your roof!”