Blu-ray discs could boost solar cell efficiency

Blu-ray discs can be used to boost solar cell performance by improving light absorption, a new study has found.
Already one of the best ways to store high-definition movies and television shows because of their high-density data storage, Blu-ray discs also improve the performance of solar cells - suggesting a second use for unwanted discs, according to researchers from Northwestern University.
The team discovered that the pattern of information written on a Blu-ray disc works very well for improving light absorption across the solar spectrum.
"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," said Jiaxing Huang, an associate professor of materials science and engineering in the McCormick School of Engineering and Applied Science.

Blu-ray discs contain a higher density of data than DVDs or CDs, and it is this quasi-random pattern, perfected by engineers over decades for data storage, that, when transferred to the surface of solar cells, provides the right texture to improve the cells' light absorption and performance.
Working with Cheng Sun, an associate professor of mechanical engineering at McCormick, Huang and his team tested a wide range of movies and television shows stored on Blu-ray discs, including action movies, dramas, documentaries, cartoons and black-and-white content, and found the video content did not matter.

All worked equally well for enhancing light absorption in solar cells.

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.
Now, researchers have 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.
They 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.

"We found a random pattern or texture does work better than no pattern, but a Blu-ray disc pattern is best of all," Huang said.
The findings will be published in the journal Nature Communications.