Nanoscale coating could make LED devices more efficient

The project, led by Ryan McCarron, a PhD student at King’s College London, succeeded in introducing a nanostructured film of gold into glass in order to scatter light.

Generally, flat-screen TVs and other devices that incorporate LEDs can only be viewed clearly head-on, with quality dropping off as the viewing angle becomes more acute. As well being a matter of viewing aesthetics though, this limits the efficiency of such devices.

‘If there’s an interface, with glass or some other material on top of the emitting layer, a significant portion of the light coming out will be trapped inside,’ McCarron told The Engineer. ‘Whenever a ray of light approaches glass beyond a certain angle, known as the critical angle, all that light is entirely reflected — none of it is transmitted through.’

In the case of glass that angle is around 42in, whereas for materials with a higher refractive index such as those used in LEDs, it can be more like 15˚, McCarron said.