Insect eyes inspire improved solar cells

Jan 20, 2011
Insect eyes inspire improved solar cells
Fabricated rolls of moth-eye film; the rolls appear green due to the color of the protection film.

(PhysOrg.com) -- The eyes of moths, which allow them to see well at night, are also covered with a water-repellent, antireflective coating that makes their eyes among the least reflective surfaces in nature and helps them hide from predators in the dark. Mimicking the moth eye's microstructure, a team of researchers in Japan has created a new film, suitable for mass-production, for covering solar cells that can cut down on the amount of reflected light and help capture more power from the sun.

In a paper appearing in Energy Express, a bi-monthly supplement to , the open-access journal published by the Optical Society (OSA), the team describes how this film improves the performance of photovoltaic modules in laboratory and , and they calculate how the anti-reflection film would improve the yearly performance of solar cells deployed over large areas in either Tokyo, Japan or Phoenix, Ariz.

"Surface reflections are an essential loss for any type of photovoltaic module, and ultimately low reflections are desired," says Noboru Yamada, a scientist at Nagaoka University of Technology Japan, who led the research with colleagues at Mitsubishi Rayon Co. Ltd. and Tokyo Metropolitan University.

The team chose to look at the effect of deploying this antireflective moth-eye film on solar cells in Phoenix and Tokyo because Phoenix is a "sunbelt" city, with high annual amount of direct sunlight, while Tokyo is well outside the sunbelt region with a high fraction of diffuse .

They estimate that the films would improve the annual efficiency of solar cells by 6 percent in Phoenix and by 5 percent in Tokyo.

"People may think this improvement is very small, but the efficiency of is just like fuel consumption rates of road vehicles," says Yamada. "Every little bit helps."

Yamada and his colleagues found the inspiration for this new technology a few years ago after they began looking for a broad-wavelength and omnidirectional antireflective structure in nature. The eyes of the moth were the best they found.

The difficulty in making the film, says Yamada, was designing a seamless, high-throughput roll-to-roll process for nanoimprinting the film. This was ultimately solved by Hideki Masuda, one of the authors on the Energy Express paper, and his colleagues at Mitsubishi Rayon Co. Ltd.

The team is now working on improving the durability of the film and optimizing it for many different types of . They also believe the film could be applied as an anti-reflection coating to windows and computer displays.

Explore further: Lord of the microrings: Team reports breakthrough in microring laser cavities

More information: Paper: "Characterization of antireflection moth-eye film on crystalline silicon photovoltaic module," Noboru Yamada, Toshikazu Ijiro, Eiko Okamoto, Kentaro Hayashi, and Hideki Masuda, Optics Express, Vol. 19, Issue S2, pp. A118-A125. Available at: www.opticsinfobase.org/oe/abst… m?uri=oe-19-102-A118

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User comments : 3

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apex01
not rated yet Jan 20, 2011
So would would this improve thin film efficiency from 11 to 16 or 17 percent?
Quantum_Conundrum
not rated yet Jan 22, 2011
Hmmm.

So does this go from say, 220 watts panel to 233 watts?

Or does it go from 220 watts to ~374 watts?

When they say "improves efficiency by X percent" how are they measuring this?

5 or 6 percent of what the panel aready does?

or 5 or 6 percent with regards to approaching an ideal panel.
Objectivist
not rated yet Feb 01, 2011
@apex & QC
There's a clear difference between percentage and percentage point. According to the article the increase was in percentage.

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