A More Efficient Solar Panel Can be Made With Old Blu-ray Discs 

By Sarah Zhang on at

Yes, a Blu-ray copy of Police Story 3: Supercop was destroyed for the sake of science. It turns out that the nanostructure of Blu-ray disc makes them especially well-suited to soaking up light—exactly what you'd want with a solar panel.

A group of researchers at Northwestern University in Illinois, US, managed to make more efficient solar panels based on the patterns on Blu-ray disc. They began by cutting off the edges a Blu-ray copy of the 1992 Jackie Chan flick Police Story 3 and opening up the disc. (It's actually not a bad movie, especially for those of you into Hong Kong capers.)

The researchers were after the quasi-random nanostructure that encode the data on the disc. IEEE Spectrum explains why the way data is stored on Blu-ray makes it relevant to solar panels, especially compared to other DVDs.

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.

The researchers then used the open face of the Blu-ray disc to make a mould that was stamped over solar panels, giving the panels the same nanostructure pattern as the original disc. The Blu-ray-patterned solar panels ended up being 12 per cent more efficient than smooth ones. Blu-ray discs may be riding the slow train to obsolescence, but certain aspects of its technology can still be repurposed for novel uses. [Nature Communications, IEEE Spectrum]

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