Scientists at the University of Toronto have created a new type of light sensor that acts like a pixel in a digital camera. Researchers believe the sensor, which takes advantage of a phenomenon called multi-exciton generation (MEG), could lead to substantial advancements in the performance of a variety of electronic devices including digital cameras.
In digital cameras and solar cells, photos are absorbed in a semiconductor and generate excited electrons, known as excitons. Normally, each photon is used to generate at most one exciton, this phenomenon limits the amount of excitons generated, but the use of MEG sensors can increase the rate of excitons produced from a single photon of light.
“Digital cameras are now universal, but they suffer from a major limitation: they take poor pictures under dim light. One reason for this is that the image sensor chips inside cameras collect, at most, one electron’s worth of current for every photon (particle of light) that strikes the pixel,” says Ted Sargent, professor in University of Toronto’s Department of Electrical and Computer Engineering. “Generating multiple excitons per photon could ultimately lead to better low-light pictures.”
Until now, nobody had collected electricity from a device that takes advantage of MEG. The development may greatly increase the power image sensor chips and conversion efficiency of solar cells.