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Recycled Blu-ray discs improve solar panels

"It's as if electrical engineers and computer scientists developing the Blu-ray technology have been subconsciously doing our jobs, too," said Jiaxing Huang.

By Brooks Hays
The patterns on the bottom of Blu-ray discs enhance light absorption on solar panels. File Photo by Keizo Mori/UPI
The patterns on the bottom of Blu-ray discs enhance light absorption on solar panels. File Photo by Keizo Mori/UPI | License Photo

CHICAGO, Nov. 25 (UPI) -- In terms of movie-watching, Blu-rays have become largely obsolete (or at least undesired) -- rendered so by the ascent of Netflix and other streaming services. But that doesn't mean the blue-bottomed discs are useless. It turns out they're great for enhancing the sun-absorbing abilities of solar panels.

The minuscule patterns etched into the bottom of the discs are perfect for capturing and scattering light onto the energy absorption technologies of modern solar panels. The discs themselves, of course, block most light. But the discs themselves aren't applied -- their pattern is simply borrowed and replicated on the panel.

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Scientists already knew a quasi-random pattern of microscopic grooves was ideal for capturing and dispersing light as it hits the surface of a solar panel. But manufacturing such a pattern is expensive. Blu-rays offer a viable shortcut.

"We had a hunch that Blu-ray discs might work for improving solar cells, and, to our delight, we found the existing patterns are already very good," Jiaxing Huang, a materials chemist and solar panel expert at Northwestern University, said in a press release. "It's as if electrical engineers and computer scientists developing the Blu-ray technology have been subconsciously doing our jobs, too."

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Huang and his colleagues at Northwestern University first created a negative mold of the bottoms of Blu-ray discs. They then pressed the Blue-ray molds into a thin coat of liquid plastic, leaving behind the Blue-ray's signature stamp. Finally, the transparent plastic sheet is placed atop the solar panels. Testing showed the Blu-ray-patterned panels were able to absorb 21.8 percent more light than regular panels.

The ideal pattern for creating an iridescent scattering effect is one that's semi-random, and extremely condensed -- Blu-ray sequencing in a nutshell.

Superior to DVDs in their data storage abilities, Blu-rays compress so much information onto such a small surface using data processing algorithms that translate video signals into a sequence of zeros and ones. While seemingly random, the sequence actually has a bit of redundancy built in, limiting too many consecutive zeros or ones.

"It has been quite unexpected and truly thrilling to see new science coming out of the intersection of information theory, nanophotonics and materials science," Huang added.

The revelation of Huang and his colleagues is detailed in the journal Nature Communications.

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