Boosting LED Efficiency: Zinc Oxide Microwires Improve Performance of Light-Emitting Diodes (LEDs)…

[OKIsItJustMe]

http://gtresearchnews.gatech.edu/zinc-oxide-led-efficiency/

10/31/2011

Boosting LED Efficiency: Zinc Oxide Microwires Improve Performance of Light-Emitting Diodes (LEDs) Through the Piezo-phototronic Effect

Researchers have used zinc oxide microwires to significantly improve the efficiency at which gallium nitride light-emitting diodes (LED) convert electricity to ultraviolet light. The devices are believed to be the first LEDs whose performance has been enhanced by the creation of an electrical charge in a piezoelectric material using the piezo-phototronic effect.

By applying mechanical strain to the microwires, researchers at the Georgia Institute of Technology created a piezoelectric potential in the wires, and that potential was used to tune the charge transport and enhance carrier injection in the LEDs. This control of an optoelectronic device with piezoelectric potential, known as piezo-phototronics, represents another example of how materials that have both piezoelectric and semiconducting properties can be controlled mechanically.

“By utilizing this effect, we can enhance the external efficiency of these devices by a factor of more than four times, up to eight percent,” said Zhong Lin Wang, a Regents professor in the Georgia Tech School of Materials Science and Engineering. “From a practical standpoint, this new effect could have many impacts for electro-optical processes – including improvements in the energy efficiency of lighting devices.”

Details of the research were reported in the Sept. 14 issue of the journal Nano Letters. The research was sponsored by the Defense Advanced Research Projects Agency (DARPA) and the U.S. Department of Energy (DOE). In addition to Wang, the research team mainly included Qing Yang, a visiting scientist at Georgia Tech from the Department of Optical Engineering at Zhejiang University in China.

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[MADem]

1. Coooool!! Hot stuff! I love LEDs--and the better they work the better I like them. nt

[formercia]

3. I remember playing with some of the first commercial LEDs in 1969

Monsanto made them, they were $500 per and about 5% as efficient as current technology.

[MADem]

4. Wow--can you imagine?

Amazing how prices can plummet!

I remember seeing a Texas Instruments calculator that couldn't do much of anything--I think it could manage a square root. It cost a hundred and ten bucks when you could get a decent apartment in Boston for three hundred. It was too big to fit in a pocket, unless it was a jacket pocket.

Years later, my bank was giving away ones that could do way more and were the size of a credit card!

[formercia]

6. It didn't take long

By 1972, they were pretty much a commodity item. Motorola even sent me 100 in a micro-miniature ceramic package as a freebie for a project I was working on.

I remember standing in line to get one of those TI calculators. They were just a plain 4 function unit at first, with an LED display. We weren't even allowed to use them in math class because the Instructor insisted that everyone use a Slide Rule. He was a Dinosaur. I walked out of class and never went back.
That's when $120 was a week's pay.

[txlibdem]

5. If you do the math you'll see that LED light bulbs are profit makers today

You don't have to wait for some new stuff to come out of the lab. LED lighting is available today and pays for itself in just a couple of years. And they last for 2 decades so you'll have to wait a long time before changing out those LED light bulbs. I calculated that one 60 watt LED bulb costing $40 will pay me back in energy savings alone in under 5 years; since they last for 20 that is pure profit for me for around 15 years!

Here is a payback calculator for LED lighting: http://www.getgreen.net.au/roi.htm

And the main thing that LED lighting does better than CFL lights: it can be made into any shape, style or type of lighting you could ever want. CFL's come in one size and are always the curly things filled with dangerous mercury.

[kestrel91316]

2. Nannies to freak out over the Zn in LEDs in 3...2....1....