'Holy Grail' of LED lighting just 5 years away

Home and office lighting could see a revolution in the next five years, according to Colin Humphreys, a materials scientist at Cambridge University.

Humphreys says the key lies with gallium nitride (GaN), a substance already used for some lighting applications such as camera flashes, bicycle lights, mobile phones and interior lighting for buses, trains and planes.

The brilliant light produced by GaN makes it the “Holy Grail” for home and office lighting, according to Humphreys. If achieved, general-use GaN lighting could reduce the typical electricity consumption for lighting of a developed country by around 75 per cent, while delivering major cuts in carbon dioxide emissions from power stations and preserving fossil fuel reserves.

“GaN LEDs have a very exciting future,” Humphreys says. “In particular they are incredibly long lasting. A GaN LED can burn for 100,000 hours — one hundred times longer than a conventional light bulb. In practice this means it only needs replacing after 60 years of normal household use. Also, unlike the energy-saving compact fluorescent lights now in use, GaN LEDs don’t contain mercury so disposal is not such an environmental headache.”

To unlock these benefits, important barriers must still be tackled by scientists. For now, GaN LEDs are too expensive to manufacture for wide-scale deployment in homes and workplaces. The harsh quality of the light produced is another limiting factor.

A detailed new theory for why GaN emits light so strongly has recently been developed at the Cambridge Centre for Gallium Nitride, where Humphreys leads the research. Developed  in collaboration with Phil Dawson of Manchester University, the theory could lead to ways of improving GaN lighting’s quality and efficiency.

“Our centre is also working on an innovative technique for growing GaN on six-inch diameter silicon wafers, rather than the sapphire wafers used to date,” Humphreys says. “This could deliver a tenfold reduction in manufacturing costs and so help GaN lighting penetrate new markets.”

The centre is also investigating how GaN lighting could be made to mimic sunlight, which could have important benefits for sufferers of Seasonal Affective Disorder (SAD).”

“GaN lighting should start making its mark in homes and offices within about five years,” Humphreys predicts. “That won’t just be good news for the environment — it will also benefit consumers in terms of convenience, electricity bills and quality of life.”

Looking further ahead, the possibilities for GaN light appear wide-ranging. Currently, GaN LEDs are phosphor-coated to transform the light from blue into white. But there could be scope to remove the coating and incorporate mini LEDs, each producing a different colour, in the overall “light bulb.” Together, the mini LEDs would produce white light, but people in the home or office could alter the precise balance, for example to a bluish light, to suit their mood.

“This and other applications, for example in healthcare for detecting tumours, and water treatment for developing countries, might be achievable in 10 years,” Humphreys says.