# 300 Lm/W! ||warmer color through nanotubes



## tvodrd (Feb 1, 2008)

Holy cow, and from researchers in Turkey.

Larry


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## 3rd_shift (Feb 1, 2008)

*Re: 300 Lm/W!*

What a neat idea!
Nanocrystals instead of phosphor. :thinking:

This could lead the way for flashlights to be as bright as houselamp bulbs and still run fine on off the shelf batteries.
3 watts kicking out 900 lumens instead of 60 watts needed for the same job. :wow:


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## Gryloc (Feb 1, 2008)

*Re: 300 Lm/W!*

Why don't Cree or Lumileds hire these scientists? With the scientists ideas, and either of the company's budget, we could have even more efficiency in no time!

These "300lm/W" measurements were with which blue die? Could it be Cree's latest EZ1000 blue die? If not, and they are getting crazy efficiencies with older and less efficient blue dies from yesterday, then woohoo!

I hope to see more of this. Some day, we will have LEDs that combine Lumileds packaging, Cree's amazing, textured EZ1000 die, and this new technology of red/green light-producing coatings. Actually, this supposably "clear" coating of red and green light producing nano-crystals should textrue the surface of the LED die much the same, if not better, than Cree's and Lumiled's coatings, right? There should be a plenty of surface area for light to escape from the die. Could this be one reason for better efficiencies? 

 (mmmmmh, buttery wait)

-Tony


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## PhotonBoy (Feb 1, 2008)

*Crystal coat warms up LED light*

http://technology.newscientist.com/...ms-up-led-light.html?feedId=online-news_rss20

"Topping LEDs with a coating of carefully tuned nanocrystals makes their light warmer and less clinical, a new study shows. The researchers argue this is a must for energy-efficient LED lights to make headway in the commercial market...."


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## Icebreak (Feb 2, 2008)

*Re: Crystal coat warms up LED light*

It might be the first time in CPF history that someone beat you to the punch on news about LED technology but tvodrd posted about it here.

Interesting stuff.


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## jtr1962 (Feb 2, 2008)

*Re: 300 Lm/W!*

I think the key is that the nanocrystals enhance extraction efficiency. I'm not sure I believe the 300 lm/W number. Even under a worst-case scenario that means the LED is 75% efficient. The blue dies used in Nichia's 169 lm/W experiment were indeed around that efficient at low currents. Here it seems they're managing to emit green and red light with similar efficiency. If the process can be commercialized then we should have LEDs in both white and colors which emit very little waste heat. This opens up a whole new world of applications.


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## IMSabbel (Feb 2, 2008)

My guess is that the 300Lm/W are just for the light emitted by those crystal.
I.E. The conversion efficiency omitting stokes losses.

Thats the only sensible way to rate that system.


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## Daekar (Feb 2, 2008)

I'm also disinclined to believe the 300L/w number outright. Such a quantum leap in progress would indeed be welcome, but I'd like to see a couple of datasheets, a NIST certification, etc. Does anybody have any further information on this advance?


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## Dodge (Feb 2, 2008)

Daekar said:


> I'd like to see a couple of datasheets, a NIST certification, etc.


Come on, this is in a research lab. The LED was presumably a one-off, which cost tens of thousands of dollars. We could be years away from productizing this.


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## eprom (Feb 2, 2008)

Hi Friends,

I have sent an e-mail to Assistant Professors Hilmi Volkan Demir for further information. I wish he will share information with us.


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## tebore (Feb 2, 2008)

I just read the article but I don't get what they are smoking, 30l/w for most commercial LEDs are they stuck in 2005? 

If everything they do is commercially available soon, the important question will be "Will it be available in the LuxIII format?"


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## Szemhazai (Feb 2, 2008)

Something is not right here, if I remember correctly ideal white light source is about 240 lm/w so 300 lm/w it a bit to high value for white light :]


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## Oznog (Feb 3, 2008)

Yeah 300lm/w might not be plausible, hard to say for sure though.

You realize if this were true, the best way to get red, green, yellow, or blue light might be to use this process to make white light and put a color filter on top of that??


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## 2xTrinity (Feb 3, 2008)

Oznog said:


> Yeah 300lm/w might not be plausible, hard to say for sure though.
> 
> You realize if this were true, the best way to get red, green, yellow, or blue light might be to use this process to make white light and put a color filter on top of that??


If you want blue light, you do absolutely nothing (even though not a phoshpor exactly, the technology was described as converting blue to other wavelengths -- so remove all coatings, and you get 100% blue) It is conceivable that these coatings, espceailly if they produce an individual color (like a particular red or green wavelength), it might be possible to make a more efficient green or red by doping a blue LED with "green nanotubes" and filtering it.

Blue LEDs have certainly improved more than the other color in efficiency, though I'm almost positive the reason for that is simply the fact that blue is what the phosphor white LEDs are based on. 



> Something is not right here, if I remember correctly ideal white light source is about 240 lm/w so 300 lm/w it a bit to high value for white light :]


I've heard the 240 lm/W number throw around a lot, but nevery any details as to exactly _what kind_ of white light being discussed. I'm guessing that refers to "equal power" between 400-700nm, or a broad spectrum 5500k. Using a warmer color temperature (3500-3000k) and a narrower band with less output in the "fringes" of the visual spectrum can dramatically improve the theoretical cap. I read one study which discussed theoretical max lumens watt for various forms of white. They found the best possible for a warm white with 80CRI (what this LED claims to be) is 400 lm/W. That means this LED would have to be 75% efficient. No matter what, those nanotubes won't be able to put out more energy in any color than the amount of energy it can absorb from blue light.


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## eprom (Feb 3, 2008)

Hi Friends, 

Many thanks to Hilmi Volkan Demir, he is very kind man and send me the detailed information link. Here is the link he sent
http://www.bilkent.edu.tr/~volkan/publications/APL_2008_HVDemir.pdf

I wish it helps,


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## jtr1962 (Feb 3, 2008)

Reading through that it seems they're talking about the luminous efficacy of the emitted spectrum here, not the conversion efficiency of an actual working LED. It's old news that combinations of RGB can in theory reach in excess of 300 lm/W.


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## 3rd_shift (Feb 3, 2008)

Interesting.
We shall see what happens.

Just make sure that the led package is:

Small, but still easy to hand, or machine solder.
Easy to mount with, or without screws.
Electrically isolated for easier mounting to metal heatsinks. (ceramic base like the cree XRE leds?)
Wide angle light output for reflectors or optics and able to take most existing ones available today with little or no modifications to them
Good white light.
Reliable and able to take some overdrive when well heatsinked in aluminum flashlights.
Not fragile. (tough enough for flashlight use.) :naughty:
Easy to buy in small numbers, or large numbers.

Did I miss anything here? :thinking:


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## bobski (Feb 5, 2008)

3rd_shift said:


> Did I miss anything here? :thinking:



Emitter life span.


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