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Brookhaven National Lab researchers improve solar panels with antireflective design, study finds

Charles Black led Brookhaven National Lab researchers in

Charles Black led Brookhaven National Lab researchers in finding a way to improve solar panels. Inspired by a spiky coating on moths’ eyes that helps the nocturnal creatures see without reflecting light rays, the researchers etched nanoscale antireflective patterns onto solar cells. The design helps prevent sunlight from bouncing off the solar panels, increasing efficiency. Black holds a sample of the material used to create the design at the Upton lab on Tuesday, Jan. 20, 2015. Credit: Heather Walsh

The secret to building better solar panels may lie in the eyes of a moth.

Researchers at Brookhaven National Laboratory say they have discovered how to etch infinitesimal patterns onto solar cells, preventing sunlight from bouncing away.

Their findings, detailed in an article scheduled to be published Wednesday in the journal Nature Communications, involves mimicking a complex antireflective coating that allows moths to see in the dark.

"If light bounces off a solar panel, you lose the energy," said Charles Black, who led the research at the laboratory, in Upton. "So we looked to nature for a solution."

Reflection has long bedeviled the efficiency of solar panels. And the industry has developed a variety ways to cut down on the amount of energy that escapes.

By and large, those solutions involve coating solar cells with a series of antireflective materials. But that makes panels more expensive and complex to manufacture.

So with funding from the U.S. Department of Energy, Black and his team set out to find a better way. Like many scientists who study light, they turned to moths.

The surface of a moth's eye is coated with a dense forest of microscopic spikes. Light easily enters that forest — but then the waves are essentially trapped by the spikes, which keep light from reflecting back out.

The characteristic allows moths' eyes to absorb more light at night and, hence, see better. Plus, eyes that don't shine in the dark are harder for predators to see. (Think of a deer in the headlights.)

Scientists have looked to moths before to improve solar panels, eye glasses and other products. But the technology remains largely experimental. Now the Brookhaven team says it has found a way to make it practical.

The key was a material that naturally forms a honeycomb pattern, with holes 20,000 times smaller than grains of sand.

The scientists coated solar panels with an ultrathin layer of the material, called block copolymer, to form the honeycomb. The series of tiny holes functioned as a stencil, allowing researchers to use a gas to burn away the exposed panel, leaving behind a forest of spikes.

"It worked even better than we thought it would," Black said. "It really gobbles up the light."

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