Quantum dots produce broad-spectrum, warm-white light

Very small quantum dots have produced white light emission, but their future potential is not clear.

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Chemists at Vanderbilt University (Tennessee) have accidentally created a source of white light using quantum dot nanocrystals of cadmium selenide (CdSe).

Graduate student Michael Bowers made the smallest possible quantum dots containing either 33 or 34 pairs of atoms – the so-called "magic size" that the crystals form preferentially.

When illuminated with a laser, the dots emitted warm-white light with a yellow tint. Normally, such dots would be expected to produce blue light.

Other groups, notably Sandia National Labs, have achieved white light emission by adding other materials to quantum dots, using a much more complex synthetic process.

The Vanderbilt group also coated an LED with a polyurethane film containing quantum dots, and again achieved white light emission.

However, it remains to be seen whether the process can be controlled to yield products with sufficient brightness for commercial applications.

For a more detailed view, read Tom Espiner's article on ZDNet UK entitled Nanocrystal sheds new light on future illumination.

Read the original story "Quantum dots that produce white light could be the light bulb’s successor" on the Vanderbilt University website.

The author's work has been published by the Journal of the American Chemical Society (subscription required).

Quantum dots replace phosphors

Evident
Evident quantum dots
Until now quantum dots have been known primarily for their ability to produce a dozen different distinct colors of light simply by varying the size of the individual nanocrystals. This capability is particularly suited to fluorescent labeling in biomedical applications.

One company that manufactures quantum dot products is Evident Technologies. At the recent LEDs 2005 meeting, Evident described how their quantum dot products could potentially be used as a down-conversion medium in place of phosphors to produce white light when combined with an LED.

To meet the growing demands for all of its nanomaterial products, Evident recently added a new Vice President for Sales, Jeffrey Goronkin, who has extensive business development and sales experience in the life science field.

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