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Thin-film solar cells could become more efficient – thanks to moths' eyes

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May 17, 2013

Inspired by moths' eyes, scientists have created new technology that may help improve the ...

Inspired by moths' eyes, scientists have created new technology that may help improve the efficiency of thin-film solar cells (Photo: Shutterstock)

Because moths need to use every little bit of light available in order to see in the dark, their eyes are highly non-reflective. This quality has been copied in a film that can be applied to solar cells, which helps keep sunlight from being reflecting off of them before it can be utilized. Now, a new moth eye-inspired film may further help solar cells become more efficient.

The film, developed at North Carolina State University by a team led by Dr. Chih-Hao Chang, is designed to minimize “thin-film interference” in thin film solar cells.

Thin-film interference is what causes gasoline slicks on water to take on a rainbow-colored appearance. Some sunlight is reflected off the surface of the clear gasoline, while some more penetrates its surface, but then is reflected back up through it by the surface of the underlying water. Because the two sources of reflected light have different optical qualities, they interfere with one another when combined – thus the rainbow effect.

The same sort of phenomenon can occur when any thin, transparent films are placed together. In the case of thin-film solar cells, which are made up of layered films, some of the sunlight is effectively lost at every film-to-film interface where the interference occurs.

To keep this from happening, Chang’s team created films with built-in cone-shaped nanonostructures, similar to those found on moths’ eyes. When present on the surface of one film, these structures are able to penetrate into the underside of a film laid over top of it, meshing them together almost like Lego pieces. As a result, much less in the way of thin film interference occurs between the two. This process could be repeated as several films are layered one on top of the other.

According to the scientists, the amount of light reflected by one of these nanostructured interfaces is one one-hundredth the amount reflected by a regular film-to-film interface. They now plan on using the technology in a solar device, with an eye towards commercial applications.

A paper on the research was published this week in the journal Nanotechnology.

Source: North Carolina State University

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away.   All articles by Ben Coxworth
2 Comments

moth eye coating consists of a hexagonal pattern of bumps, each roughly 200 nm high and spaced on 300 nm centers.[6] This kind of antireflective coating works because the bumps are smaller than the wavelength of visible light, so the light sees the surface as having a continuous refractive index gradient between the air and the medium, which decreases reflection by effectively removing the air-lens interface.

Antony Innit
19th May, 2013 @ 12:22 am PDT

"the amount of light reflected by one of these nanostructured interfaces is one one-hundredth the amount reflected by a regular film-to-film interface" -- gotta love figures like those!

moreover
27th May, 2013 @ 11:04 am PDT
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