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Scientist hope to put LEDs to work in brilliant new ways

LEDs, light emitting diodes, are a very old invention, with the first visible-light diode being invented in 1962.  They consist of a junction of semiconducting material, such as a silicon or gallium compound.  However, scientists today are looking to teach this old dog some new tricks, and putting LEDs to work in a plethora of creative uses.

The magic is in the material.  While LEDs have been around for a long time, new and exotic materials are being used and older materials are being tweaked and reformulated to provide, a wider range of colors, brighter light, and higher efficiency.

The result is that LEDs may soon be permeating our lives in new ways.  LEDs are already invading the automobile headlight industry and are in high demand due to their superior life and brightness. 

Now one place scientists are looking to plant the LED is in the home.  Tungsten lightbulbs have a very low 5% efficiency, compared to modern LEDs, which have around a healthy 40% efficiency.  The result is power savings, increased brightness, and superior life.  Obstacles standing in the way of this development are the still higher cost of LEDs and the fact that LEDs' white light has much more blue than sunlight or natural bulbs.  However, these obstacles are fading as costs slowly drop and scientists develop better material blends to provide more yellow to the LED's emissions, making for a warm light that would be welcome in many a household.

Scientists are also looking to put tiny LEDs to a new use in the lab and eventually in commercial internet connections -- quantum cryptography.  Tiny streams of photons in the system would pass from the LED to the a detector.  Any interception of the beam (ie. snooping) would result in the signal being altered, as per the observer effect.  Such a system, when properly implemented would be in theory immune to any sort of malicious interception between the sender and the receiver.

Yet another use for the little lights has been proposed by scientists -- this one with promise of bringing new high-tech hope to impoverished regions.  One of the world's largest problems is the lack of clean drinking water in third-world nations.  Chemicals can be used to treat drinking water, but they are often expensive, toxic, and require a large amount of infrastructure.  A frequently used alternative is high-energy UV light known as "deep UV", emitted from special UV bulbs.  Passing a beam of this light through water kills most bacteria and destroys most viruses cleanly and simply.  The issue with this system is bulbs constantly need to be replaced and are two bulky for small scale use.

Scientists feel the answer is deep UV LEDs.  While they are still working on perfecting the materials, researchers,  such as Dr Rachel Oliver, an LED researcher from the University of Cambridge, think it is just a matter of time before the optimal combination of materials is found. 

"Deep-UV can't be made from the combination of materials we're used to, although I certainly think it's possible," Dr. Oliver stated.

Dr. Oliver is among many researchers striving to put LEDs to use in new and creative ways.  She sees LEDs being commercially implemented in the aforementioned uses within 10 to 20 years.

For now these prospects still remaining cost prohibitive and are dependent on material breakthroughs, but the future sure looks bright for these little devices.  And companies are looking to put LEDs today to a different and even more outlandish use -- clothing -- every airport security officer's worst nightmare

Whatever their form, LEDs are transforming the way we light and see our world.

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Don't forget...
By Spartan Niner on 12/15/2007 11:21:46 PM , Rating: 4
Tungsten lightbulbs have a very low 5% efficiency, compared to modern LEDs, which have around a healthy 40% efficiency. The result is power savings, increased brightness, and superior life.

... and a direct result of the higher efficiency and lower power draw is that it produces less heat ! Quite important to those of us who live in warmer climates :)

RE: Don't forget...
By timmiser on 12/16/2007 12:40:22 AM , Rating: 2
That is important too. So does anybody know how this percent efficiency scale works? What would be 100% efficient?

RE: Don't forget...
By lumbergeek on 12/16/2007 2:04:05 AM , Rating: 3
100% efficiency would mean 100% of the energy input would be converted to photons - zero heat or other by-product radiations.

RE: Don't forget...
By CubicleDilbert on 12/16/2007 7:07:58 AM , Rating: 3
LED efficieny is always 100% due to recombination of electrons and their counterpart (positive holes).
The problem is, however, that most photons are immediately absorbed by the surrounding material, which results in heat.
At Osram in Germany, they only recently invented a mirror like material which can reflect and direct the released photons out from the material into the plastic diffusor. (Check their press material).
I assume, this would allow for the very first time to have some real powerful LEDs.
So far, all LED lamps have really dissappointed me because their effective lumen intensity is piss poor.

RE: Don't forget...
By masher2 (blog) on 12/16/2007 12:23:55 PM , Rating: 4
> "100% efficiency would mean 100% of the energy input would be converted to photons - zero heat or other by-product radiations. "

No. 100% efficiency means not only that all the input is converted to photons, but what portion of that spectrum is visible to human eyesight. Incandescent bulbs convert nearly all their input to photons...but most of the photons are in the infrared range, which makes for a very low luminous efficacy.

Interestingly enough, a 100% efficient light source isn't possible with "white" light. Such a source would be monochromatic at 555 nm (a bright green).

RE: Don't forget...
By Souka on 12/16/2007 10:25:00 PM , Rating: 2
and what is effeciency of CFL?

(assuming all bulbs put out equal light, at similar quality...what is effeciany comapred to the 60w incandecent?)

60w incadencet bulb = 5% effeciency
60w equavlent LED bulb = 40% effeciency
60w equavlent CFL bulb = ?

RE: Don't forget...
By masher2 (blog) on 12/17/2007 1:58:07 AM , Rating: 2
I don't know where Jason got those figures, but the LED bulbs I've seen are less than 10% efficiency (though another poster in the thread has a link to some in the 15% range). Fluorescent "tube" lighting is about 15% as well, whereas the CFL bulbs with integrated balasts are generally about half that.

A 60w tungsten bulb is more along the lines of 2% efficient.

RE: Don't forget...
By Oregonian2 on 12/17/2007 3:34:46 PM , Rating: 2
And unless one has an IR LED, having light be non-visible isn't a problem most of the time AFAIK because most LEDs are roughly monochrome (not counting things like ones using phosphors or multiple die).

RE: Don't forget...
By akugami on 12/16/2007 2:30:16 AM , Rating: 3
Not just warmer climates, heat is a problem in many areas that require lighting as it would take extra cooling to dissipate the heat.

For one, server farms and data centers where there are a large amount of computer equipment running in very tight confines. There needs to be sufficient light to see by, especially when trying to look through a spaghetti web of wires. But the extra heat from lighting means more cooling is needed. Not only would leds save money from more efficient use of power, but it also produces less heat which means you save money again on cooling.

Grammar Police: The issue with this system is bulbs constantly need to be replaced and are two bulky for small scale use.

Should read "too" and not "two" I'm going to assume. :)

RE: Don't forget...
By mallums on 12/16/2007 8:05:09 AM , Rating: 1
LEDs are interesting, but the best efficiency to be had is from fluorescents. They are typically 90% efficient vs. 40% or so from the best LEDs. The main drawback is that they contain mercury. While there is much less mercury in newer bulbs, there is work to be done. Nevertheless, I believe that the future lies with fluorescent technology, not LED tech.

RE: Don't forget...
By zsdersw on 12/16/2007 8:11:47 AM , Rating: 3
Oh, I wouldn't be so quick to judge where the future is going to be. LED's limitations and drawbacks are not so insurmountable.

RE: Don't forget...
By masher2 (blog) on 12/16/2007 12:27:04 PM , Rating: 2
> "fluorescents are typically 90% efficient vs. 40% or so from the best LEDs"

No. The best fluorescents are in the 15% range. That's better than commercially available LED lighting (which runs up to 10%), but not as good as research-grade LEDs now being made in labs.

RE: Don't forget...
By codeThug on 12/16/2007 1:33:06 PM , Rating: 2
compared to modern LEDs, which have around a healthy 40%

Mash, The article mentions 40% for modern LEDs. I'm assuming this means "state of the shelf" not "start of the art". You mention commercial LED lighting being 10% efficient. I'm trying to understand the disparity here.

Is the Author talking monochromatic LEDs(40%) vs commercial lighting white LEDs(10%)? 10% seems fairly low even for white LEDs. Are there other losses involved in commercial LED lighting?

RE: Don't forget...
By masher2 (blog) on 12/16/2007 3:50:49 PM , Rating: 2
I won't speak for the author, but luminous efficiency is easy enough to calculate yourself. I looked up a page on LED light bulbs and took the first one which came up:

The best bulb on that page generates 150 lumens for 2.75 watts. That's an efficacy of 54 lm/W. Divide by 683 and you get an efficiency of around 8%.

Nichia here claims an efficacy of 3X that, but I don't believe these are on shelves yet:

RE: Don't forget...
By mindless1 on 12/16/2007 11:22:49 PM , Rating: 2
There are more efficient LEDs available today such as Cree XR-E series, a Q5 grade at 94 lm/W efficacy being available in quantity and soon the R-grades are expected in volume.

Focusing on Q5 as the contemporary offering, 94/683 = 14%

The C.Crane product really isn't suited for room lighting, a fluorescent alternative, as it's use of 40 LED then require either increased focus as a spotlight or enough diffusion to significantly reduce usable output. Granted, a Cree XR-E isn't a finished product shaped like a bulb, but given different requirements than an incandescent bulb the opportunity to shun a traditional bulbed lamp fixture design, in favor of more integration, is possible.

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