Old Blu-ray disks could help make better solar panels

According to a new study in Nature Communications, the patterns etched onto Blu-ray disks could be harnessed in the engineering of solar panels.

Blu-ray disks get their vibrant hue from the microscopic structures etched into their surface — tiny pits that encode the movie’s data. It turns out that nanoscopic pits and grooves can also make solar panels more efficient by increasing the light absorption of the material they’re on. The best patterns for this are quasi-random — not so random as to absorb useless wavelengths across the spectrum of sunlight, but not so orderly that they only absorb a single wavelength. But creating somewhat random, itty-bitty patterns of this nature from scratch can be expensive.

Researchers at Northwestern University decided to recycle the existing patterns on Blu-ray disks for use on solar panels. They created stamps by pouring liquid plastic onto some Blu-rays (they chose “Police Story 3: Super Cop,” presumably because of its presence in some retail bargain bins) and then pressed these into the surface of new solar panels to give them the same etching.

Sure enough, the Blu-rayed solar panels absorbed more sunlight than ones that hadn’t been stamped.

And no, the secret wasn’t Jackie Chan’s acting — in further experiments, the researchers found that any movie would do. It turns out that Blu-ray disks encode their movie data into patterns that are just random enough to enhance light absorption.

“Of course, other Blu-ray movies would work as well,” co-author Jiaxing Huang told the Verge. “The main excitement of our paper is that … Blu-ray algorithms convert the video and audio signals into universally quasi-random patterns.”