Moth eyes could lead to more efficient solar cells

Chuck Bednar for redOrbit.com – @BednarChuck

The compound lenses found in the eyes of moths have inspired a team of researchers to develop a new antireflective coating that could make solar cells more efficient than ever before.

In a recent edition of the journal ACS Nano, researchers at the Agency for Science, Technology and Research in Singapore explain that compound lenses found in nocturnal moth eyes helped lead to a coating that can also sharpen the view of solar cell image sensors.

Important non-reflective pattern

The moths ocular faculties contain micro lenses (ommatidia) which are patterned with nanoscale dome-shaped bumps that help reduce the reflection of light at multiple wavelengths, according to Gizmodo. These ommatidia make it possible for the moths to navigate in the dark.

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“The ability to capture light and not let go is appealing in the world of solar cells because it can increase efficiency,” the website added. “So the team from Singapore has taken inspiration from the complex lens structure to create a process that stamps patterns over the surface of a material, replicating the antireflective effects of the moths’ eyes.”

The researchers used a process known as nanoimprint lithography, in which nickel molds are used to imprint microscopic patterns onto the surface of a polycarbonate. After they stamped a series of these 200-nanometer diameter domes onto the surface, they imprinted a second series of larger lens shapes (2 to 25 microns across) onto the same material.

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The result, Gizmodo said, was a surface covered in a pattern that closely resembled the moths’ eyes. During tests, the study authors found that their surface reflects just 4.8 percent of light between 400 to 1,000 nanometers in wavelength, and they hope that these treatments can be used on solar cells to ensure that they absorb as much light as possible.

Even when the researchers varied the angle of the light, the nanodome-decorated arrays continued to perform about twice as well as non-treated surfaces, said Chemical and Engineering News. The next step will be to demonstrate that these techniques can scale up to make coatings suitable for larger materials, and they might use a roller printer to accomplish that feat.

Help from nature



The Singapore researchers aren’t the first scientists to copy natural eyes in order to improve solar cells. Last month, scientists at Helmholtz-Zentrum Berlin and the Max Planck Institute for the Science of Light looked at the fovea centralis (the tiny structure that makes out central vision sharp) to boost the efficiency of these power-generating panels.

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According to Gizmag, the researchers analyzed the underlying mechanisms that guide the fovea and altered them to silicon as a surface for collecting light in solar cells. The fovea centralis is comprised of several closely-packed funnel-like inverted cones that are connected directly to the nerve cells of the eye, and thus provide visual detail when we read a book or watch TV.

After observing how the cones of this structure are capable of trapping large amount of light in well-lit environments, the study authors were able to develop photovoltaic technology that could increase light absorption in thin-film solar cells up nearly two-thirds. A paper reporting on their findings was printed in the journal Nature Scientific Reports.

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Source: http://www.redorbit.com/news/science/1113348002/moth-eyes-could-lead-to-more-efficient-solar-cells-030615/