Bowers and McBride brought the resulting picture to Rosenthal, who called it "the most beautiful thing I've ever seen."
According to Rosenthal, researchers had long known different-size quantum dots produce different colors. Few scientists, however, had predicted that a very small nanocrystal would give off white light, which is a combination of all colors.
"It wasn't proven before. It wasn't even really predicted, that we know of," Rosenthal said. The team soon realized the huge potential Bowers' nanocrystals had for the lightbulb industry.
The lightbulbs in your home are still very similar to the ones first invented by Thomas Edison over a century ago.
An incandescent bulb is a glass tube filled with a non-reactive gas that contains a thin metal filament. When electric current runs through the filament, the atoms within the filament vibrate, causing it to emit both light and lots of heat.
The heat is wasted energy. Researchers have long anticipated that LEDs, found in everything from digital clocks to car dashboards, could replace lightbulbs.
LEDs use a greater proportion of the electricity flowing through them, so they emit less heat. In fact, LEDs are cool to the touch.
This translates into savings for consumers. Widespread adoption of LEDs could cut U.S. consumption of electricity for lighting by 29 percent, according to the U.S. Department of Energy.
And unlike fragile glass bulbs, LEDS are made from sturdy wafers of semiconducting materials. An LED can last up to 50,000 hours50 times as long as a 60-watt bulb.
But creating white-light LEDs has been problematic. Only recently have researchers come up with LEDs as powerful as incandescent and fluorescent bulbs. And these news LEDs give off light with a harsh, bluish tinge that can be unpleasant to human eyes.
"The holy grail for the [LED] industry is to penetrate the lighting market. The industry is working very hard on that," said Robert Steele, director of optoelectronics research for technology firm Strategies Unlimited in Mountain View, California.
Lightbulb purchases add up to 15 billion U.S. dollars in sales a year, Steele said. Bowers' coating may help put LEDs next to those bulbs on hardware store shelves.
"It is a good step forward. Any work along these lines is worthy of attention," Steele said.
He noted that similar, ongoing research is funded by countries such as the United States, Korea, China, and Taiwan. A number of private companies are also developing their own quantum-dot technologies.
Meanwhile, the Vanderbilt team admits that much work remains to make the crystals cheap and sturdy enough for commercial use.
"We're cautiously optimistic," Rosenthal said.
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