LED efficiency puzzle solved by UC Santa Barbara theorists

[OKIsItJustMe]

http://iee.ucsb.edu/news/led-efficiency-puzzle-solved-uc-santa-barbara-theorists

LED efficiency puzzle solved by UC Santa Barbara theorists

(Santa Barbara, Calif., April 19, 2011) -- Researchers at the University of California, Santa Barbara, say they’ve figured out the cause of a problem that’s made light-emitting diodes (LEDs) impractical for general lighting purposes. Their work will help engineers develop a new generation of high-performance, energy-efficient lighting that could replace incandescent and fluorescent bulbs.

“Identifying the root cause of the problem is an indispensable first step toward devising solutions,” says Chris Van de Walle, a professor in the Materials Department at UC Santa Barbara who heads the research group that carried out the work.

Van de Walle and his colleagues are working to improve the performance of nitride-based LEDs, which are efficient, non-toxic and long-lasting light sources. They investigated a phenomenon referred to as “droop”—the drop in efficiency that occurs in these LEDs when they’re operating at the high powers required to illuminate a room. The cause of this decline has been the subject of considerable debate, but the UC Santa Barbara researchers say they’ve figured out the mechanism responsible for the effect by performing quantum-mechanical calculations.

LED droop, they conclude, can be attributed to Auger recombination, a process that occurs in semiconductors, in which three charge-carriers interact without giving off light. The researchers also discovered that indirect Auger effects, which involve a scattering mechanism, are significant—a finding that accounts for the discrepancy between the observed degree of droop and that predicted by other theoretical studies, which only accounted for direct Auger processes.

…

Reference:
“Indirect Auger recombination as a cause of efficiency droop in nitride light-emitting diodes”
doi: http://dx.doi.org/10.1063/1.3570656">10.1063/1.3570656

…

[FormerDittoHead]

1. They're getting around to figuring this stuff out NOW? Where have the light bulb companies been?

LEDs have been around since the 1960's. That's like 50 years, folks.

WHY hasn't GE (who invented the thing), Sylvania, Phillips, Westinghouse, etc already figured this stuff out?

This is the failure of "the market". With all the money in light bulb business, we have to wait until NOW then look toward public universities for innovation?

Why haven't those companies forked out a tiny bit of their BIG FAT PROFITS and turned it toward solving how to, excuse me, take the LEDs which have been around since 1962 and use them to light rooms?

[Speck Tater]

2. Why would a company that depends on selling you new light bulbs every month...

want a bulb that potentially lasts forever?

The last thing they want is to give you a reason to NOT buy their product more than once. If they can't sell bulbs to repeat customers they can't make money, so they have to lay off workers and close plants. Our economy is based on consumption. Anything that reduces consumption is bad for our economy. That's why we need an economy with a different kind of structure entirely. (No, I don't have a clue how it would work.)

[txlibdem]

4. +1

We need a totally different economic structure but it should not feature the pursuit of money nor reward greed and sociopathic behavior.

[mountainlion55]

6. zeitgeist move forward

Its a documentary on how to create a resource based economy in stead of the consumer based one we have now. :hippie:

[Tesha]

3. Calm down.

LEDs have undergone a number of fundamental shifts
in technology since those first infrared LEDs came
out. The big breakthrough (IMNSHO) was a practical
blue LED because that finally enabled the production
of broad-spectrum light that we humans would call
"white light".

But that's a relatively new development.

It's no surprise that we're still discovering
fundamental things about solid-state light production.

As a comparison, you might ask yourself how many decades
it took between the first roll-out of carbon-based
incandescent lamps and the discovery and popularization
of the tungsten-halogen lamp. And even now, selective
reflector materials may yield a (literally) quantum
leap in the efficiency of incandescent lamps.

Not *EVERYTHING* is a conspiracy to deprive us of
the future that is rightfully ours; some things are
just hard work and take time.

Tesha

[Throckmorton]

5. What he said N/T

[Nihil]

7. (She) n/t

:hi:

[Javaman]

8. What did I tell you about bringing common sense and facts into a discussion?

don't make me come back there!

Thanks for the info.

Cheers. :)

[Confusious]

9. ahhhh! facts! nonono nonono

conspiracy theories are the real truth! phear! science can't do anything! take charge of your own health! science can do everything! why haven't they done it yet? greed money sell u ligthbulbs and drugs to keep u alive but not cure u!