Huge development (maybe).

Even brighter LEDs. Of course, I won't get my hopes up until NewBie weighs in on this, but it seems like this could make every recent improvement in LEDs seem like a joke.

Sure would be nice. I'll take a 150 watt laser pointer sized EDC anytime.

Wow! Hmm. If I am reading this correctly, they coated a blue LED with these "quantum dots" mixed in polyurethane and that, alone, gave off about as much light as a 60 watt incadescant bulb? Am I reading this right? Wow! I mean, that article does not mention the size of the LED used, but I am guessing it isn't the sized of a standard 60 watt bulb. What do you all think? I'd like this in my flashlight!

Ooh! I misread, it is twice as bright as a 60 watt bulb! *drool*

Another story with photos and a much better description:

http://www.sciencenewsdaily.org/story-7421.html

http://exploration.vanderbilt.edu/news/news_quantumdot_led.htm

FYI, Sandia and others have been fiddling with quantum dots for light. Sandia had a story on this at least two years ago.

They are real, and provide much promise, and this fella looks to have accidentally blundered into the JackPot/HolyGrail of quantum dots, like an ignorant oaf.

These sorts of things happen on occasion, and is great news. Even better is the common cheap materials they made those dots from. YAG:Ce is what the LED phosphor is called, but whats in it? Rare Earth Cerium-doped yttrium aluminum garnet (there is a mouth full).

The study estimated that wine consumption in the United States would grow by 28.6 percent from the 2003 figure to 27.66 million hectolitres (7.19 billion gallons) in 2008.

The quantum dots are made from cadmium selenide (CdSe) nanocrystals, which are what photocells/NiCd/some types of solar cells/some types of rectifiers/xerographs, use, and is used in all sorts of products that sense light, as well as vulcanizing agents. So Cadmium and Selenium are rather common, so this type of quantum dot materials are low cost too.

Not that each LED uses much phophor anyhow, the entire Luxeon cost them under 0.25ea to actually make. This huge profit margin LumiLEDs has climatized the market to, is one area that I am very excited to see competition in, to get the prices down significantly. The rumor mill has it, that high power LEDs should fall to 1/2 their current price within the next year. This isn't due to cost reduction in the production, just competition in the market.

Unfortunately, LumiLEDs has the most expensive packaging on the market, and is also very process intensive. But they aren't down to the pricing levels yet, where different high power LED packages make much difference in the profit margins.

BTW, here is the link for the original paper. If anyone is a member of ACS, or can somehow snag this, I'd sure be interested in reading it!!!!! Please PM me if you can snag it!
http://pubs.acs.org/cgi-bin/abstract.cgi/jacsat/asap/abs/ja055470d.html

Ah! Way to butcher the original articles! Haha. Thanks for the more informative posts Newbie. The original articles say that LEDs, in general, can be brighter, but doesn't say this particular one is. Damn, way to mislead the reader! Still, exciting stuff.

Isn't that interesting how highly ignorant reporters routinely screw things up? I wonder if the fella that reported on MSN had some sort of agenda.

Don't worry though, there are still several developments in the labs still working their way to market.

One is a surface structure change, and another is a shape change, each of which are supposedly able to get twice the amount of light out of the LED die. I don't know if the two techniques can be combined.


Then there are at least two phosphors that emit twice the light as the ones in use now.


If folks can get around the IP/Patent issues, or liscense them, we could be looking at parts that are 4x brighter than they are now.

CREE already announced their 70lm/W white LEDs by independent testing. Though this was a Lab part. As I understand it, they are working very hard to get this to market as soon as possible.

Seoul Semiconductor has been abuzz with rumors of a 100lm/W part, but there has been no independent testing, and it was still in the early research phase.

If LumiLEDs doesn't get their act together soon, they are going to be a has been, who initially forged the trail, but died by the wayside. It is sad they will be loosing the technical and scientific strength of the crew at Agilent, who did much of the work, especially fixing things, for the fledgling company. IMHO, Philips has not been an innovator, but acquires companies and is good at mass marketing established technologies and getting them to the customer. Now the other half of the company has been purchased by the co-owner, Philips, it will be interesting to see what happens to the young company. In fact, with the aquisition, and Philips often swallowing companies and using their products internally and not allowing any more sales to other companies, there were fears that the LumiLEDs parts would be going off the market. Their CEO had to specifically address this in one of the conference calls. But a good thing to come out of this, is that Agilent is now free to produce their own high power parts, no longer being constrained from entering the market with high power parts of their own. They were not allowed to do this when LumiLEDs was under their umbrella.

"Isn't that interesting how highly ignorant reporters routinely screw things up? I wonder if the fella that reported on MSN had some sort of agenda."
Unlikely.
A headline in a local newpaper stated that our department had saved another home in our town.
The reporter heard the dispatch on his scanner. "Possible chimney fire."
When he got there he would have noticed, no fire and no hose on the ground.
I was standing there when the chief told him there was no fire, just smoke in a room, probably from an inversion.

The reporter does have a great way of taking pictures. He holds his camera at chest height and snaps from there. He can then check it and take another if need be.
If good, he has a great candid shot with a relaxed subject.

You are right, alot of reporters these days seem to try and make news from nothing.

NewBie said:

One is a surface structure change, and another is a shape change, each of which are supposedly able to get twice the amount of light out of the LED die. I don't know if the two techniques can be combined.


Then there are at least two phosphors that emit twice the light as the ones in use now.


If folks can get around the IP/Patent issues, or liscense them, we could be looking at parts that are 4x brighter than they are now.

Click to expand...

Just wondering, is that 4x brighter for a part that performs like typical Luxeons (~35 lm/W) or will these enhancements work for all parts? The reason I'm asking is that if you take Cree's XT-27 blue die you already have 42% efficiency so getting twice the light out the LED die brings us to 84%. Nice but I wonder if that would even be possible. Likewise, the best white LEDs tested to date are ~100 lm/W and maybe 30% efficient at converting power to light. It would be impossible to increase their brightness by a factor of 4 since that would be over 100% efficient. I'll hazard a guess then that a factor of 4 brightness increase wouldn't apply across the board.

Regardless, if this brings even low end LEDs to at least 150 lm/W then it's welcome news. I'd personally love to see 90%+ efficient LEDs sooner rather later as it makes the heat issue practically moot.

jtr1962 said:

Just wondering, is that 4x brighter for a part that performs like typical Luxeons (~35 lm/W) or will these enhancements work for all parts? The reason I'm asking is that if you take Cree's XT-27 blue die you already have 42% efficiency so getting twice the light out the LED die brings us to 84%. Nice but I wonder if that would even be possible. Likewise, the best white LEDs tested to date are ~100 lm/W and maybe 30% efficient at converting power to light. It would be impossible to increase their brightness by a factor of 4 since that would be over 100% efficient. I'll hazard a guess then that a factor of 4 brightness increase wouldn't apply across the board.

Regardless, if this brings even low end LEDs to at least 150 lm/W then it's welcome news. I'd personally love to see 90%+ efficient LEDs sooner rather later as it makes the heat issue practically moot.

Click to expand...

Ah, but you are looking at those little die there, for little tiny SMT LEDs and 5mm LEDs which only produce 27mW from 30mA.

It is a different ball of wax, once you step up to the plate with a real die that folks would use in high power LED parts.

CxxxXB900-Sx000-A
http://www.cree.com/products/pdf/CPR3CM.pdf
On the lowest end you start out at 90mW output and head north of 165mW on the high end, with 350mA.
(side note, some have been asking about the Vf of the CREE, here is a good place to look)

What I am trying to say is that things are a world apart in the high power LEDs, as far as losses. A fella needs to think of them quite differently.

NewBie said:

Ah, but you are looking at those little die there, for little tiny SMT LEDs and 5mm LEDs which only produce 27mW from 30mA.

Click to expand...

Actually, the 27mW is at 20mA. With a typical Vf of 3.2V that gives the 42% efficiency figure I mentioned.

It is a different ball of wax, once you step up to the plate with a real die that folks would use in high power LED parts.

CxxxXB900-Sx000-A
http://www.cree.com/products/pdf/CPR3CM.pdf
On the lowest end you start out at 90mW output and head north of 165mW on the high end, with 350mA.
(side note, some have been asking about the Vf of the CREE, here is a good place to look)

What I am trying to say is that things are a world apart in the high power LEDs, as far as losses. A fella needs to think of them quite differently.

Click to expand...

OK, so getting a potential 2X more light out of the die with the new process gets us to somewhere between 180 mW and 330 mW. With Vf=3.3V typical at 350 mA according to the data sheet, that would mean efficiencies in the 15.6% to 28.6% range. Even the improved efficiencies are nowhere near the present efficiencies of the 5mm dies.

Anyway, I guess that answers my question. White power LEDs can easily get an overal 4 times efficiency boost and still not be anywhere near their limits. It would be nice to see some 150 lm/W parts, at least in the lab, with these improvements.

BTW, any idea if that 42% efficiency of the XT-27 die is starting to bump up against any real limits, or can we expect 5mm dies with efficiencies of 50%, 60%, or more in the near future?

What about the potential for coating all of the light exposed surfaces like the reflector?

NewBie, PM sent regarding the PDF.
If someone else needs/wants a copy of the PDF drop me a PM or e-mail.

jtr1962 said:

The reason I'm asking is that if you take Cree's XT-27 blue die you already have 42% efficiency so getting twice the light out the LED die brings us to 84%. Nice but I wonder if that would even be possible.

Click to expand...

TANSTAAFL (There Ain't No Such Thing As A Free Lunch)

If the dots were 50% efficient, then your total output would be 50% of 42% or 24% total output.

For the same wattage the percentage of energy converted to visible light might be twice as high with LEDs and dots as compared to incan but you can't get more out than you put in.
(except in dog hair where the mass of the hair is greater than the total intake of the dog, especially if metabolic residue is considered.)

jtr1962 said:

Actually, the 27mW is at 20mA. With a typical Vf of 3.2V that gives the 42% efficiency figure I mentioned.


OK, so getting a potential 2X more light out of the die with the new process gets us to somewhere between 180 mW and 330 mW. With Vf=3.3V typical at 350 mA according to the data sheet, that would mean efficiencies in the 15.6% to 28.6% range. Even the improved efficiencies are nowhere near the present efficiencies of the 5mm dies.

Anyway, I guess that answers my question. White power LEDs can easily get an overal 4 times efficiency boost and still not be anywhere near their limits. It would be nice to see some 150 lm/W parts, at least in the lab, with these improvements.

BTW, any idea if that 42% efficiency of the XT-27 die is starting to bump up against any real limits, or can we expect 5mm dies with efficiencies of 50%, 60%, or more in the near future?

Click to expand...

Actually, on the 7090, I've already seen reels of parts from 300mW bins (or higher...), 9 months ago, and this is out of the package, not just the die. They'll be bumping that by another good bit soon.

The main problem right now, from my understanding on the blues, is its just re-absorption in the die, as the light bounces around inside the die. They just need to figure out how to extract it more efficiently. Otherwise it just gets re-absorbed, and turns into heat.

The CREE efficiency bump will be great, we are looking at a nice improvement in output due to one improvement being implemented, but the other great thing, the energy being emitted as light, will not be turning into heat, meaning that the LED will run cooler. You can take this one of two ways. First, it is cooler. Or you can run it harder, just producing the same amount of heat as before, and get alot more light out of it.

I hate to break this guys bubble, but I had a discussion about using Q dots and nano wires as a replacement for phos with LL almost 18 months ago. At that time they were already well into a testing program comparing various materials to each other and standard phos materials.

It is one thing to demo a glow, it is entirely another to prove reliability and consistent color mixing. Keep in mind, that the Q dots and nano wires emit in VERY narrow bands, so great care would be needed to avoid having your LED emit in "spikes".

HarryN said:

I hate to break this guys bubble, but I had a discussion about using Q dots and nano wires as a replacement for phos with LL almost 18 months ago. At that time they were already well into a testing program comparing various materials to each other and standard phos materials.

It is one thing to demo a glow, it is entirely another to prove reliability and consistent color mixing. Keep in mind, that the Q dots and nano wires emit in VERY narrow bands, so great care would be needed to avoid having your LED emit in "spikes".

Click to expand...

Thats the whole point of this discovery. It is a wide band from cyan and rolling off around orange. A little bit better than the YAG:Ce. Other previous techniques did do bands and spikes.