ETH chemical engineers have produced the purest green with a light-emitting diode. This is good news for TV displays. Credit: Sudhir Kumar / ETH Zurich
Chemical engineers from ETH Zurich have succeeded in generating ultra-pure green light for the first time. The new light-emitting diode will pave the way for visibly improved colour quality in a new generation of ultra-high definition displays for TVs and smartphones.
Chih-Jen Shih is very satisfied with his breakthrough: "To date, no one has succeeded in producing green light as pure as we have," says the Professor of Chemical Engineering in his laboratory at the Hönggerberg campus. He points at an ultra-slim, bendable light-emitting diode (LED), which displays the three letters "ETH" in a fine hue of bright green.
Shih's progress is significant, particularly in terms of the next generation of ultra-high resolution displays used for TVs and smartphones. Electronic devices must first be able to produce ultra-pure red, blue and green light in order to enable the next generation of displays to show images that are clearer, sharper, richer in detail and with a more refined range of colours. For the most part, this is already possible for red and blue light; green light, however, has hitherto reached the limits of technology.
This is due mainly to human perception, since the eye is able to distinguish between more intermediary green hues than red or blue ones. "This makes the technical production of ultra-pure green very complex, which creates challenges for us when it comes to developing technology and materials," says Sudhir Kumar, co-lead author of the report.
Up to 99 percent ultra-pure green
It becomes clear from reference to the Rec.2020 standard just how much progress Shih's ultra-green light has made in the development of the next generation of displays. The international standard defines the technical requirements for ultra-high resolution (known as "Ultra HD") displays and provides a framework for further research and development. The requirements also include an improvement in colour quality visible to the naked eye. The standard provides the colour scale that a display can reproduce and therefore a broader range of colour hues.