The white LED revolution

While incandescent light bulbs lit the 20th century, LED lamps are lighting up the 21st century, or at least the first two decades.

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Published: Sat 18 Oct 2014, 9:28 PM

Last updated: Fri 3 Apr 2015, 9:44 PM

LED lamps are not only efficient and energy-saving, but are also long lasting and are helping light up the homes of hundreds of millions of poor people around the globe.

Recognising the great promise that LED lamps hold in improving the quality of life over 1.5 billion people in the developing and under-developed world, who lack access to electricity grids, The Royal Swedish Academy of Sciences awarded this year’s Nobel Prize in Physics to three inventors of efficient blue light-emitting diodes (LEDs), which has brought bright and energy-saving white light sources to the world.

Isamu Akasaki and Hiroshi Amano, two Japanese researchers, and their compatriot, Shuji Nakamura, who teaches in the US, were given the prestigious award for their ‘revolutionary’ invention of greatest benefit to mankind. The Nobel committee cited their efforts at producing bright blue light beams from semi-conductors in the early 1990s, triggering a fundamental transformation of lighting technology.

The first LED was created in 1927 by Russian scientist Oleg Losev, but the discovery did not lead to any practical devices. About three decades later, low-intensity infrared LEDs were used in some electronic components, but the real breakthrough came in the early 1960s when Professor Nick Holonyak Jr, while working at General Electric, developed the first, visible spectrum, red LED. (The ageing professor, who has strangely not been awarded the Nobel, had never grumbled about it all these years; but after the Swedish academy declared the new winners, he said he felt insulted at his team being ignored over the decades).

Other scientists, including some of Prof Holonyak’s former students, created green and yellow LEDs, but the much sought after blue LED (which would ultimately lead to the white LED) remained elusive. The three Japanese scientists produced the LED with the colour blue, which is near the top of the visible spectrum, heralding white LED technology.

White LED lamp technology is evolving at a rapid pace and is getting more energy efficient. While traditional bulbs emit light with an efficiency of 16 lumen per watt (lm/W), current LED lamps have touched a record of 300 lm/W. While incandescent bulbs last for just 1,000 hours (and fluorescent lamps, which have an efficiency of 70 lm/W last for 10,000 hours), LED lamps can function up to 100,000 hours.

For hundreds of millions of people in the developing world, the new technology means they can light up their homes even without having access to grid power, as the LED bulbs can be powered by inexpensive solar power.



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