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LIGHT BULBS ARE old-school energy hogs. Adoption of light-emitting diodes (LEDs) might be able to halve lighting energy consumption and cut CO₂ emissions by 258 million metric tons a year. Today, LEDs are found in accent lighting and flashlights, but they're not white enough for general use. That may change, thanks to a chance discovery by Vanderbilt University chemists led by Sandra Rosenthal. The key ingredient: quantum dots—tiny semiconductor crystals (in this case, cadmium selenide) that absorb light and generate a charge. Lab members James McBride and Michael Bowers had made nanocrystals so small they verged on the molecular. When Bowers pointed a laser at these "nano-nano" crystals, he anticipated violet or UV light but saw white. "He knew something was up," Rosenthal says, "so he mixed the batch with Minwax floor polyurethane and coated a violet LED. It glowed white!" Now the team hopes to make the LEDs brighter. "It's too early to tell whether it will be a quantum dot LED or some other approach," Rosenthal says. "But I do believe solid-state lighting will revolutionize the way we light our homes."

BULB SLAYER
Innovators:
Michael Bowers, James McBride, Sandra Rosenthal

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