One of the most curious discoveries made recently within the Northwestern University, Illinois is that the technology behind Blu-ray Discs may in fact make better solar cells than the solar boards that have been used so far.
The almost accidental discovery was made when researchers had the epiphany of comparing the way both Blu-ray discs and solar cells function. Surprisingly, both devices use quasi-random nanostructures, but in different ways. Solar cell efficiency increases with the number of photons it can capture and convert into electricity, so in an attempt to improve their functionality, scientists have developed a method of applying nanometer sized materials on the surface of the cells to help disseminate light. Blu-ray discs, on the other hand, suffer this transformation when data is encoded on its surface, the necessary quasi-random nanostructures forming in random sequences for error tolerance.
The pattern resulted through encoding on a Blu-ray seems to be of almost ideal texture and to top it off, the data on the disc does not matter, the effect remaining the same. The initial experiment was run on a Blu-ray copy of Police Story 3: Supercop, where researchers delaminated the surface of the disc and transferred the pattern onto a solar panel using a special mold. The results scored by the Blu-ray-patterned panels showed an increase of 21.8% in light absorbed, compared to regular panels. The experiment was then performed on different Blu-ray movies, solidifying the theory that the key lies in a randomized pattern, and not in the actual strings present on the disc’s surface. For further proof, the experiment was then repeated on blank Blu-ray discs, but the periodicity of the pattern on it did not show much effectiveness in trapping photons.
According to materials chemist and solar panel expert Jiaxing Huang, the objective of solar panels is to improve light capture over the whole solar spectrum, anywhere between 350 and 2,300 nanometers, instead of focusing on particular wavelengths. Because of the way they are built, Blu-ray discs are etched with a quasi-random pattern of pits that measure 150 to 525 nanometers, allowing them to capture photons in the visible and near infrared portions of the spectrum.
This discovery has intrigued scientists because of how fortunate the potential of recycling Blu-ray discs may be. Fabrication of patterned solar panels is not the most cost-effective practice of our days, and this alternative might just offer us a nifty shortcut to converting solar energy into electricity.