There may come a day when your roof has a solar panel made from old Blu-Ray discs. Ok, so it probably won’t be copies of The Expendables taped together, but researchers have created a more efficient solar panel thanks to the them.
“Blu-ray disc patterns are surprisingly well suited for light-trapping applications,” the study authors wrote in their abstract.
Photon management dictates how efficient a solar panel is. Quasi-random nanostructures are used to increase photon management, but fabricating them to create the optimal nanostructures is expensive.
Researchers at Northwestern University found these quasi-random nanostructures exist in Blu-ray movie discs. IEEE Spectrum touches on what makes a Blu-ray disc so special in this case.
The binary data on a full Blu-ray disc, on the other hand, has a nanostructure that’s very different. It consists of compressed binary sequences that have been applied with an error control modulation, so that all those segments of ones and zeros (physically translated into islands and pits on the surface of the disc) are always between two and seven digits long. Since the length of a single digit is 75 nanometers, a full disc ends up being etched with a quasi-random pattern of islands and pits ranging in length from 150 nm to 525 nm. These dimensions happen to be “near optimal” for trapping photons in the visible and near infrared portions of the spectrum.
With a copy of Police Story 3: Supercop in hand, the researchers created a mold that was used to give solar panels the same nanostructure pattern as the Blu-ray movie. This Blu-ray patterned panel absorbed nearly 22% more light than a traditional solar panel. That translates to about a 12% rise in power conversion efficiency.
A simulation run by the researchers points to Blu-ray patterns being applied for solar cells made with other materials.
Now, the solar panel industry needs to see how this works on a larger scale. The infrastructure for printing data on Blu-ray discs is there. Re-purposing it for solar panels could help drive prices a lot lower and increase adoption of the green technology.