Blue LEDs: A Noble Winner of The Nobel Prize

Three scientists, Isamu Akasaki, Hiroshi Amano and Shuji Nakamura, have been awarded the Nobel Prize in Physics for their work on blue LEDs.

Since the development of the first blue LEDs in the early 1990s, these have revolutionised the world around us through their applications in a miriad of popular electronic devices, which have significantly improved efficiency and helped reduce the high power consumption needs of our growing world population.

LEDs, Light Emitting Diodes, have been around as practical electronic components for half a century. LEDs are semiconductor devices designed to emit light of a particular colour, and whilst infrared (red) and mid-range green light emission was quickly achieved, ones to emit blue light at the high-energy low-wavelength end of the light spectrum have proven most tricky.

Why are blue LEDs so important? They were the last development required to create white light LEDs, which use less power and last longer than traditional devices that emit white light. White LEDs are incorporated in the smartphones and computer screens that we all use every day.

The breakthrough in the research work came with the production of high-quality gallium nitride which is in many layers of the blue LED device, structured to enable efficient light emission. The red and green LEDs previously developed used gallium phosphide, a far easier chemical to produce. A white LED is simple to make from a blue one, by exciting a fluorescent chemical in the lightbulb which changes the blue light to white light.

A modern white LED is a highly efficient device which converts more than 50% of the electricity input into emitted white light, compared to only about 4% efficiency in conventional incandescent lightbulbs. LEDs can last 10 times longer than fluorescent lights and 100 times longer than incandescent lightbulbs. Using LEDs in houses and commercial buildings helps to significantly reduce the lighting-based electricity needs, around a quarter of all generated power. As the LEDs only require a low amount of energy to function, they could operate using cheap solar power, giving the possibility of providing better lighting to some 1bn people without access to the main electricity grids.

Nakamura's and Akasaki's groups will continue work on making even more efficient blue LEDs. In future, scientists may be able to develop white LEDs that work by combining red, green and blue LEDs, which would mean a light which could provide a range of colours across the spectrum.