March 7, 08
New NanoCrystal LEDs are up to 10X More Efficient at Creating Light

Researchers at Bilkent University in Ankara, Turkey, have made an amazing discovery that could be the big breakthrough that brings LEDs into every home. They discovered that by coating blue LEDs with a layer of nanocrystals specially engineered to turn the blue light into warm white, they could produce light at an efficiency of over 300 lumens of visible light per watt. Typical white LEDs are less well matched to human eyes and provide only about 30 to 60 lumens of visible light per watt, which means the new nanocrystal LEDs are between 5 and 10 times more efficient than standard LEDs, and that would make them about 3x more efficient than CFLs which run at about 80 lumens/watt.

The researchers used two different sizes of nanocrystals, which emit particular wavelengths of either green light or red light. The right mix of the two combines with blue light from the base LED to make a warmer white with twice as much red as blue or green.

LEDs have the potential to be far more efficient than other lights, but face two major hurdles. Firstly, they trail behind fluorescent lights for efficiency and, secondly, the color of typical commercial LEDs isn't pure white.

Most emit a "cool" light with a bluish tinge, sometimes called "lunar white", that most people find unattractive in the home. Now researchers have used nanocrystals to create LEDs that give off a warm white light.

Their LEDs have a high "color rendering index" of more than 80 out of 100, meaning objects will tend to appear their usual color under the light. That is similar to the best fluorescent lights, but behind incandescent bulbs which define the index with a benchmark of 100."