Quasi-random nanostructures have attracted interests for photon management purposes. To optimize such patterns, typically very expensive fabrication processes are needed to create the pre-designed, subwavelength nanostructures.
While quasi-random photonic nanostructures are abundant in nature, interestingly, they also exist in Blu-ray movie discs, an already mass-produced consumer product.
That quasi-random pattern of Blu-ray discs, when transferred to the surface of solar cells, provides the right texture to improve a solar cells' light absorption and performance, according to the researchers. When a disc is placed on the surface of a solar cell, light is scattered more effectively, increasing a cell's efficiency. The overall broadband absorption enhancement of a Blu-ray patterned solar cell was measured to be 21.8 percent, the researchers report.
The secret has to do with data compression. The data processing algorithms in the Blu-ray standard are achieving as high a degree of compression as possible by converting the video signals into a seemingly random sequence digital data. In addition, they are ncreasing error tolerance by adding controlled redundancy into the data sequence, which also limits the number of consecutive 0s and 1s.
These have resulted in a quasi-random array of islands and pits (0s and 1s) with feature sizes between 150 and 525 nanometers. And this range seems to work well for light-trapping applications over the entire solar spectrum.