VU discovery could spark a revolution in lighting

Tiny crystals hold promise of energy-saving illumination

By MICHAEL CASS
Staff Writer


If recent research at Vanderbilt University bears fruit, we might not need light bulbs anymore.

Vanderbilt chemists have discovered a way to create white light with extremely tiny crystals. They say those "nanocrystals" could be used with light-emitting diodes, or LEDs, the devices often used to illuminate your alarm clock's digital display, your cell phone or your car's brake lights with what's known as solid-state lighting.


LEDs use electricity much more efficiently than fluorescent light bulbs because they use it simply for light, while light bulbs also spend a great deal of it on heat, said Sandra Rosenthal, an associate professor of chemistry at Vanderbilt. So if the white-light LEDs could be mass-produced at a reasonable cost, they could revolutionize the way indoor lighting is produced.

"It doesn't look that impressive," Rosenthal said of a small prototype, which looks like a lumpy, glowing Q-Tip, "but down the road it could be pretty important."

While a national switch to solid-state lighting could save tens of billions of dollars a year by 2025, according to the U.S. Department of Energy, the impact on the environment would be at least as significant, Rosenthal said.

"Saving money is one thing, but if we cut down on electricity use, we'll cut down on greenhouse gases," she said. "We're not promising to solve global warming, but we're cautiously optimistic."

Rosenthal and graduate chemistry student Michael Bowers have applied to patent the invention. Bowers says he expects that process to be "grueling," and he and Rosenthal say they have no idea what it could ultimately mean financially for them or for Vanderbilt, which owns the researchers' work but generally splits any profits with the inventors.

Any such worries will be the offshoots of a thrilling discovery. The "eureka" moment arrived by chance in an eighth-floor campus laboratory on a weekend afternoon last summer, when post-doctoral student James McBride asked Bowers to produce a batch of nanocrystals.

The first couple of batches weren't small enough for McBride's research purposes, so Bowers made the smallest crystals he could.

Each crystal, or "quantum dot," was about one-millionth as big as the width of a human hair.

Once he made the nanocrystals, Bowers put them in a solution, put the mixture in a glass cell, and lit it up with a laser.

He expected a blue or violet light, but he saw a warm white glow instead.

"We took a material that normally would emit very narrow colors and got it to emit white light — and full-spectrum white light," Bowers said.

"Full-spectrum" means the light contained all the wavelengths — from the shortest, violet, to the longest, red — that make up the visible spectrum. In that sense, the light produced by the nanocrystals was similar to sunlight, Bowers said.

When she saw the result, Rosenthal saidd, she told Bowers, "That's the most beautiful thing I ever saw."

But Bowers wasn't done. Finding a can of Minwax that another student had brought to the lab, he decided to mix the polyurethane with the nanocrystals and coat an LED's bulb with the mixture. That experiment also produced white light.

The ease with which Bowers produced the light bodes well for the chances of replicating the results on a much larger scale, Rosenthal said.

"The reason you don't see more (LEDs) already is that they're expensive," she said. "So the fact that he was able to produce it so cheaply looks good."

Jim Brodrick, who oversees solid-state lighting research at the U.S. Department of Energy in Washington, D.C., said the federal government supports improving lighting efficiency through greater use of relatively inexpensive solid-state lighting.

Even if solid-state lighting doesn't saturate the market by 2025, significant market penetration would save $20 billion to $30 billion a year, Brodrick said.

"We feel there's a great deal of energy to be saved, and that energy translates into money back into consumers' pockets," he said.

But a question remains: Why do the crystals emit white light at that size, but not at a slightly larger size? What's the science behind the discovery?

Bowers, a fifth-year doctoral student from Fairmont, W.V., hopes to know the answer soon.

"We're trying to figure out why it does what it does," he said.

When they figure it out, Bowers and Rosenthal hope that they can get a scientific paper published in Nature, a scholarly journal. They already have written one that was published in the Journal of the American Chemical Society.

News organizations have asked about the discovery. Bowers said he was surprised by all the interest.

"I knew it was important," he said, "but I didn't think it would get this kind of attention."

It could get a lot more if it revolutionizes the way you light up your living room.

As I mentioned in another thread, big

yeah i thought it needed its own thread

I would also like to discuss how we all conserve. As well as using fuorescent in myhouse, I also recycle, glass, aluminum, and plastic(working on paper). But I drive 35 miles to work everyday, so I still suck.

Good idea. Do you want me to edit the title of the thread so more people will see it? If so, tell me what you want it to say.

This biggest one for me, by far, is that I've currently been on pace of buying gas about once a month for the past half a year or so (if we ignore a little PJ road trip ) I've been able to get jobs since being back from college where I can commute by bike. Helps when I can live so close to downtown as well.

Big recycler as well--why do you have problems with paper? I also hate it when the checkers at grocery stores overbag things (Reid know about this ). I'm also on record somewhere in the forum as not liking traditional lawns for houses.

EDIT: and I'll see how long I can go this winter without having to resort to the electric heater.

yes, change the title, Light Emitting Diodes isn't sexy enough. My only problem with the paper is laziness. I dont have a proper receptical yet. Thats all I need to get on it.

We recycle. The city of Sac makes it very easy. You don't have to seperate everything, just throw it in the big blue bin. We end up with more trash recylced than thrown away (though much of the recycling is due to my newspaper subsciption and beer habit).

We got new windows in our house this year and I think its going to have a big effect on our heating bill. Though it hasn't gotten too cold yet I can already tell the difference. It just doesn't get as cold in the house at night. We've only turned the heat on twice for a couple hours in the morning (and it's just one wall unit) so far this year.

* I compost.
* I recycle (though the city).
* I work in a home-based office.
* I turn off the water when I brush my teeth.
* I used florescent bulbs where they fit in my house.

how do you compost?

All our kitchen waste, yard waste, and all the leaves that I can fit go into a bin in back. Once it's nice a juicy it goes into the garden.

do i have to build something?

the LEDs on my stereo quit working in less than a year. The ones on my dad's stereo downstairs don't work either.
I think I'll take the con- argument.

Wait. Vanderbilt is in Nashville, Tennessee. Something smells fishy here.

*I recycle all cardboard and paper
*turn off water when I'm not brushing my teeth
*I have several compact fluorescent and/or halogen bulbs around the house, two of which have been going for 2 1/2 years
*I keep things unplugged when I'm not using them. Tv, vcr, dvd, stereo, etc.
*through the day I rarely have any lights on, I just open the blinds
*I don't ever turn the ac/heat up too much. There are a few months out of the year when the weather is perfect and I just open windows. If I get cold I just put on more clothes
*when it's warm enough, I ride my bicycle around town. I'd do it more if I lived closer to downtown where all the action is
*I drive a Honda Accord, which is pretty good on gas

As far as LEDs going bad.... I've got several clocks and other gadgets that I've had for a decade or more that still work perfectly. I don't think I've ever had one go out that quick NAT

now how long before bammer jumps in here and tells us we're a bunch of gay hippies?

You can build it or buy it. Or if you want, but make a cylinder out of chicken-wire and throw stuff in there. Some people take composting really seriously, but I just basically throw stuff in a pile.

Where I live, sorting our garbage into compost, waste, and recyclables (paper, metal, glass, plastic, and corrugated cardboard) is mandatory. The compost, which includes all organic material as well as some paper products like tissues and boxboard (like the kind used for cereal boxes) is trucked off to a compost facility and when it has cooked long enough, it is packaged and sold. They're losing tons of money on this venture, but generally the populace here is willing to pay the higher taxes for the good of the earth. Hippies.

They arent just more economic...they also last muuuuuch longer