A self-cleaning, anti-reflective coating that mimics the structure of moth eyes could find application in windows that clean themselves and solar panels that are more efficient. Credit: sootyskye on Flickr (Creative Commons License)
Self-cleaning, antireflective coatings are big news these days—and rightly so. (Click here to read a recent post about the self-cleaning coating that’s stopping solar from soiling itself).
With calls for cleaner and greener energy, and a growing reliance on solar, a coating that cleans itself and captures more light has surpassed “nice-to-have” and become a necessity. It’s just part of the reason why the unique structure of one new coating is drawing attention like moths to a flame.
Developed by researchers at the University of Cambridge’s Cavendish Laboratory, the self-cleaning, thin-film coating mimics the hexagonal structure of moth eyes, which are covered with a nanostructured film that’s naturally anti-reflective.
According to a university press release, the problem with most synthetic moth eye coatings lies in the fact that “the tiny spaces which make the coating antireflective in the first place can very quickly become clogged with dirt, which cause the antireflective effect to be lost.”
Not so with Professor Ulli Steiner and team’s coating, the larger pores of which combat clogging and are created from titanium dioxide nanocrystals. Because of the photocatalytic nature of these nanocrystals, light breaks down dirt to its most basic—carbon dioxide and water (which eventually evaporates).
Their testing has shown that oils contained in a fingerprint could be broken down in 90 minutes. Additional testing will determine whether the material—which, because it relies on UV light for photocatalysis, is “currently only suitable for outdoor applications”—could be adapted for the indoors or find application in building glass and solar cells.
“When generating energy from solar cells, you have to fight for every percentage gain in efficiency,” says Steiner. “The coating we’ve developed combines two interesting scientific principles, and could increase the amount of light getting into the solar cells.”