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Accidental Invention Points to End of Light Bulbs Bjorn Carey
LiveScience Staff Writer
LiveScience.com 
Fri Oct 21, 5:00 PM ET



The main light source of the future will almost surely not be a 
bulb. It might be a table, a wall, or even a fork.

An accidental discovery announced this week has taken LED lighting 
to a new level, suggesting it could soon offer a cheaper, longer-
lasting alternative to the traditional light bulb. The miniature 
breakthrough adds to a growing trend that is likely to eventually 
make Thomas Edison's bright invention obsolete.


LEDs are already used in traffic lights, flashlights, and 
architectural lighting. They are flexible and operate less 
expensively than traditional lighting.


Happy accident 


Michael Bowers, a graduate student at Vanderbilt University, was 
just trying to make really small quantum dots, which are crystals 
generally only a few nanometers big. That's less than 1/1000th the 
width of a human hair.


Quantum dots contain anywhere from 100 to 1,000 electrons. They're 
easily excited bundles of energy, and the smaller they are, the more 
excited they get. Each dot in Bower's particular batch was 
exceptionally small, containing only 33 or 34 pairs of atoms. 


When you shine a light on quantum dots or apply electricity to them, 
they react by producing their own light, normally a bright, vibrant 
color. But when Bowers shined a laser on his batch of dots, 
something unexpected happened. 


"I was surprised when a white glow covered the table," Bowers 
said. "The quantum dots were supposed to emit blue light, but 
instead they were giving off a beautiful white glow."


Then Bowers and another student got the idea to stir the dots into 
polyurethane and coat a blue LED light bulb with the mix. The lumpy 
bulb wasn't pretty, but it produced white light similar to a regular 
light bulb.

White light from Bowers' lumpy new bulb. Credit: Vanderbilt 
University 

The new device gives off a warm, yellowish-white light that shines 
twice as bright and lasts 50 times longer than the standard 60 watt 
light bulb.


This work is published online in the Oct. 18 edition of the Journal 
of the American Chemical Society.


Better than bulbs 


Until the last decade, LEDs could only produce green, red, and 
yellow light, which limited their use. Then came blue LEDs, which 
have since been altered to emit white light with a light-blue hue. 


LEDs produce twice as much light as a regular 60 watt bulb and burn 
for over 50,000 hours. The     Department of Energy estimates LED 
lighting could reduce U.S. energy consumption for lighting by 29 
percent by 2025. LEDs don't emit heat, so they're also more energy 
efficient. And they're much harder to break.


Other scientists have said they expect LEDs to eventually replace 
standard incandescent bulbs as well as fluorescent and sodium vapor 
lights.


If the new process can be developed into commercial production, 
light won't come just from newfangled bulbs. Quantum dot mixtures 
could be painted on just about anything and electrically excited to 
produce a rainbow of colors, including white.


One big question remains: When a brilliant idea pops into your mind 
in the future, what will appear over your head? 

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