Solar cells as thin as a flake: Toronto physicist shows how to trap light
Photonic crystals can hold light in a tiny space. In a University of Toronto video, Sajeev John explains how this could make solar cells about 50 times thinner.
Photo: U.S. Naval Research Laboratory / Wikimedia Commons, Public domain (cropped and resized)
Video: YouTube · University of Toronto · youtube.com
The University of Toronto published a profile and a video about Sajeev John on 22 October. The physicist is regarded as one of the founders of photonic crystals – artificial materials with a regularly repeating structure that can trap and guide light within a certain frequency range. Eli Yablonovitch independently proposed a similar concept; the two papers appeared in the same journal a few weeks apart.
In the video, John explains how photonic crystals could make solar cells much thinner. According to the university, the silicon is about one-fiftieth the thickness of conventional cells and absorbs near-infrared sunlight better. Such cells could cover building and vehicle surfaces; prototypes are being developed with partners in Germany and Australia.
The technology already has other uses: hollow-core fibres based on photonic crystals are already used for laser treatments in medicine; in future, such procedures could also be done through flexible endoscopes. John's team is also working on chips designed to detect disease from a drop of blood. Optical microchips that compute with light instead of electricity are another possibility – although the technology still lags behind theoretical predictions there, John cautions.