Could a Blu-ray disc improve solar-cell performance?
December 12, 2014
Here’s an idea: recycle that old grade-B movie Blu-ray disc to improve your future solar collector. Well, sort of. It turns out the Blu-ray data storage pattern when used with a solar collector increases light absorption by 21.8 percent, according to new research from Northwestern University, thanks to Blu-ray discs’ quasi-random pattern and high data density.
The researchers tested a wide range of movies and television shows stored on Blu-ray discs, including action movies, dramas, documentaries, cartoons, and even black-and-white content, and they found the video content did not matter. All worked equally well.
In the field of solar cells, it is known that if texture is placed on the surface of a solar cell, light is scattered more effectively, increasing a cell’s efficiency. Scientists have long been searching for the most effective texture with a reasonable manufacturing cost.
The Northwestern researchers have now demonstrated that a Blu-ray disc’s strings of binary code 0s and 1s, embedded as islands and pits to store video information, give solar cells the near-optimal surface texture to improve their absorption over the broad spectrum of sunlight.
In their study, the researchers first selected the Jackie Chan movie “Supercop.” They replicated the pattern on the active layer of a polymer solar cell and found the cell was more efficient than a control solar cell with a random pattern on its surface.
The researchers looked closely at the data processing algorithms in the Blu-ray standard and noted the algorithms serve two major purposes:
- Achieving as high a degree of compression as possible by converting the video signals into a seemingly random sequence of 0s and 1s; and
- Increasing error tolerance by adding controlled redundancy into the data sequence, which also limits the number of consecutive 0s and 1s.
These resulted in a quasi-random array of islands and pits (0s and 1s) with feature sizes between 150 and 525 nanometers. And this range, it turns out, works quite well for light-trapping applications over the entire solar spectrum, the researchers found.
The National Science Foundation supported the research, published Nov. 25 in the journal Nature Communications. No werewolves were harmed in the research process.