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Cause of LED Efficiency Droop Finally Revealed

Soulskill posted about a year and a half ago | from the it-was-the-daleks-all-along dept.

Technology 308

An anonymous reader writes "Researchers from the University of California, Santa Barbara, in collaboration with colleagues at the École Polytechnique in France, have been able to prove the theory behind LED 'droop.' LED droop is the term for how LEDs emit less light when the amount of current being pushed through them goes above a certain level. 'The cost per lumen of LEDs has held the technology back as a viable replacement for incandescent bulbs for all-purpose commercial and residential lighting.' Now that we understand what causes this, we should start to see research go into technology to circumvent LED Droop. 'LEDs have enormous potential for providing long-lived high quality efficient sources of lighting for residential and commercial applications. The U.S. Department of Energy recently estimated that the widespread replacement of incandescent and fluorescent lights by LEDs in the U.S. could save electricity equal to the total output of fifty 1 GW power plants.'" A pre-print of the team's paper is available at the arXiv.

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Slashdot Sucks Now (-1)

Anonymous Coward | about a year and a half ago | (#43532513)

It makes me sad.

Re:Slashdot Sucks Now (-1)

Anonymous Coward | about a year and a half ago | (#43532525)

They let the astroturfers take it over.

Just leave it to them, they can enjoy their vast marketing echo chamber without any real readers.

but won't somebody think of the Mercury? (1, Funny)

Anonymous Coward | about a year and a half ago | (#43532515)

Or toxins, or radio waves, or autism that LEDs cause?

Re:but won't somebody think of the Mercury? (0)

Anonymous Coward | about a year and a half ago | (#43533171)

yes incandecants do none of that, ball of fire with lead solder with an antenna in the middle

Re:but won't somebody think of the Mercury? (3, Informative)

ThePeices (635180) | about a year and a half ago | (#43533463)

but won't somebody think of the Mercury? Or toxins, or radio waves, or autism that LEDs cause?

What mercury? Ain't none in LED's.
LED's don't emit radio waves. The power supply might ( but utterly harmless levels ), but not LED's
LED's don't cause autism.

LED's don't do anything, except emit light and get a bit warm.

OP: Education. Get one.

Re:but won't somebody think of the Mercury? (4, Funny)

immaterial (1520413) | about a year and a half ago | (#43533541)

Whoosh. Sense of humor. Get one.

multiply (5, Insightful)

Randle_Revar (229304) | about a year and a half ago | (#43532529)

>the total output of fifty 1 GW power plants

Soooo... 50 GW?

Re:multiply (5, Funny)

Anonymous Coward | about a year and a half ago | (#43532565)

Witch!

Don't you come in here and git all European-like and start a-quotin' your Systeme Internationale at me. I likes my units in New Imperial, and thats how's they're gonna stay if I done have anything to done say abouts it.

Re: multiply (5, Funny)

Anonymous Coward | about a year and a half ago | (#43532577)

Great Scott!!! 50 Jiggawatts!?!

Re: multiply (-1)

Anonymous Coward | about a year and a half ago | (#43533157)

50 Nigga whats?

Re: multiply (0)

Anonymous Coward | about a year and a half ago | (#43533447)

Great Scott!!! 50 Jiggawatts!?!

So does this mean LEDs can help you travel through time?? That's heavy! I always did have trouble thinking fourth-dimentially.

Re:multiply (5, Funny)

conorpeterson (2718139) | about a year and a half ago | (#43532593)

>the total output of fifty 1 GW power plants

Soooo... 50 GW?

Or by my own calculation, 41.32 lightning bolts! Great Scott!

Re:multiply (1)

luke923 (778953) | about a year and a half ago | (#43532915)

Or, 41.32 Mr. Fusions.

Re:multiply (1)

mark-t (151149) | about a year and a half ago | (#43532983)

Only one lightning bolt actually. The power output of a lightning bolt is in the terawatt to tens of terawatts range.

Re:multiply (2)

TempestRose (1187397) | about a year and a half ago | (#43533083)

Card Revoked.
Back to the future? Buehler?

Re:multiply (2)

mark-t (151149) | about a year and a half ago | (#43533165)

I get the BTF reference. My point was only that you wouldn't need 50 lightning bolts to get 50GW, since even a single lightning bolt has on the order of a terawatt or more of power (so you could get 1.21GW from a single lightning bolt as well).

Re:multiply (2)

camperdave (969942) | about a year and a half ago | (#43533385)

So what you're saying is that a lightning bolt that struck, say, a clock tower, would have enough energy to fuse the clock and still have enough power to drive a circuit needing a smidge over 1200 MegaWatts - if it were timed right.

Re:multiply (-1)

Anonymous Coward | about a year and a half ago | (#43533455)

Yes, yes, we understand. You are humor impaired and feel you must reveal every bit of knowledge you have so you don't feel horribly inferior.

Re:multiply (0)

Anonymous Coward | about a year and a half ago | (#43533257)

If there were only a way to capture and effectively store all that energy. 1-10 TW of DC voltage is huge. A few lightning bolts would be enough to power an entire city for awhile.

Re:multiply (1)

antdude (79039) | about a year and a half ago | (#43533525)

"This is heavy." ;)

Re:multiply (3, Informative)

Anonymous Coward | about a year and a half ago | (#43532665)

50 1GW plants do not equal 50GW as the output is not continuously at their maximum. It also doesn't equal one 50GW plant in the fact that one central plant would need a lot of infrastructure to distribute the power around the whole country. Since the economy would be very spread and not localized, it means 50 1GW plants distributed across the network.

Re:multiply (4, Funny)

NemoinSpace (1118137) | about a year and a half ago | (#43532803)

In much the same way that 50 inane AC responses does equal the coherency of the parent.
Invariably, like a game of "telephone", the subject switches to cars. -reading at -1 is the only true freedom. Moderation is an oxymoron.

Re:multiply (1)

Randle_Revar (229304) | about a year and a half ago | (#43532829)

Yeah that is true but it is a weird way to say it. Just give us the actual estimated GW savings. Or if you want a comparison, say "equal to 50 large nuclear power plants" (or medium or coal plants or whatever is accurate).

Re:multiply (0)

Anonymous Coward | about a year and a half ago | (#43532787)

That would be one freaken massive 50GW power plant then...
or over two times the output of the Three Gorges Dam...
or around 6 time the output of the largest nuclear power plant in the world...

Re:multiply (4, Insightful)

chrismcb (983081) | about a year and a half ago | (#43532795)

Yeah, they say that like everyone knows what a "1 GW power plant" is... Is that a typical plant? Is it a small one? Is that the one you might see that powers a university, or one that powers a big city? Or is that about the size of the Manitoba Hydro Limestone hydroelectric generating station?
Ohh look Mr. Wiki claims that 55 GW is about the peak daily consumption of Great Britain in 2008. Wouldn't that have been more meaningful to say?

Re:multiply (1)

Like2Byte (542992) | about a year and a half ago | (#43532905)

or,

50 states? 1 GW each? Stupid summary. Now I'll never know!

Re:multiply (1)

guttentag (313541) | about a year and a half ago | (#43533033)

>the total output of fifty 1 GW power plants

Soooo... 50 GW?

"What the hell is a GW?!" Looks around, confused. "What?! I thought "jigawatt" was abbreviated JW? Isn't it easier to say 'almost fifty pre-Fukushima Fukushimas?'"

Looking forward to replacing a bulb... never (1)

eksith (2776419) | about a year and a half ago | (#43532531)

Well, at least after I replace them the first time.

Brain wandering time: If these are the kinds of lights we'll be putting in long duration spacecraft, it would make sense that they last at least a few decades, since it's cost prohibitive to bring supplies and, if we're talking about Mars, that's potentially a permanent installation (precluding "lunar module" style landers meant to take off later).

Re:Looking forward to replacing a bulb... never (4, Informative)

ShanghaiBill (739463) | about a year and a half ago | (#43532783)

This is why LEDs are already used in traffic lights. If you look at the cost of sending out a crew, putting up cones, flagging traffic around the workers, etc., the cost of replacing a bulb can run into kilobucks. Even if the bulb itself is more expensive, it is far more cost effective to use LED traffic lights to avoid the traffic problems, labor costs, and safety problems of burnt out incandescents.

Re:Looking forward to replacing a bulb... never (0)

Anonymous Coward | about a year and a half ago | (#43532813)

Indeed, but oddly enough around here they only use the LEDs for side streets, I have yet to see any along arterials.

Re:Looking forward to replacing a bulb... never (1)

cheater512 (783349) | about a year and a half ago | (#43533013)

In Australia the pattern seems to indicate that it depends how many incandescents the council has in supply before they replace them.
They will also replace all the lights at once rather just one blown one.

If bulbs haven't blown they won't pro actively replace them.

Re:Looking forward to replacing a bulb... never (1)

Anonymous Coward | about a year and a half ago | (#43532835)

But but those new-fangled LEDs get frozen with the snow, so they're utterly and completely unsuited to use to replace the precious Edison bulbs which serve to show how exceptional America is.

Never mind that a simple electric resistor could be added to the design, or a guy with a blower could do it, it's all about patriotism.

Re:Looking forward to replacing a bulb... never (4, Informative)

Jah-Wren Ryel (80510) | about a year and a half ago | (#43532923)

You don't even need a resistor, just a smarter hood. [thedenverchannel.com]

Re:Looking forward to replacing a bulb... never (1)

Fluffeh (1273756) | about a year and a half ago | (#43532995)

Why don't lights in the US have these covers anyway? We don't have much snow at all around here in Australia, but we still put the hoods on to stop glare from the sun making it difficult to see what the light signal is (as shown in the big image here [theage.com.au] .

Re:Looking forward to replacing a bulb... never (1)

Khyber (864651) | about a year and a half ago | (#43533049)

Shit, here in the USA we have waveguides installed on many street lights so you can't see the actual light color until you're almost on top of it.

Re:Looking forward to replacing a bulb... never (4, Funny)

Shark (78448) | about a year and a half ago | (#43533133)

You have to be a pretty bad driver to end up on top of a traffic light though.

Re:Looking forward to replacing a bulb... never (0)

Anonymous Coward | about a year and a half ago | (#43533327)

If you don't like the way I drive, get off the sidewalk... morons!

Re:Looking forward to replacing a bulb... never (1)

Khyber (864651) | about a year and a half ago | (#43533405)

Have you seen Los Angeles or Memphis drivers?

Re:Looking forward to replacing a bulb... never (1)

Kreigaffe (765218) | about a year and a half ago | (#43533597)

everyone in tennessee believes they are a professional driver on a closed course

Re:Looking forward to replacing a bulb... never (1)

Anonymous Coward | about a year and a half ago | (#43533051)

Lights in the US do have hoods. Its just that snow can build up inside the hood when it is swept by wind. The hoods detailed have a design with no bottom and an air vent that prevents snow from building up. Those hood you have installed would be great for trapping snow if it ever snowed there.

Re:Looking forward to replacing a bulb... never (1)

Fluffeh (1273756) | about a year and a half ago | (#43533103)

Hmmmm, okay. The way that I was reading it, they have only started putting hoods on the lights now.

Re:Looking forward to replacing a bulb... never (0)

Z34107 (925136) | about a year and a half ago | (#43532975)

Q: What kind of mind thinks traffic lights that don't work during blizzards without a round-the-clock crew of bulb sweeps is a good idea?

A: The same one that considers "snow" an example of American exceptionalism.

Re:Looking forward to replacing a bulb... never (0)

Anonymous Coward | about a year and a half ago | (#43533263)

Q: What kind of mind misses the obvious sarcasm, and that the reference was to the LIGHT BULBS, not the Snow?

A: Yours.

Re:Looking forward to replacing a bulb... never (2)

dbIII (701233) | about a year and a half ago | (#43533067)

So, blaming the LED for the bad design of the cover? Didn't think too much before posting did you?

Re:Looking forward to replacing a bulb... never (0)

Anonymous Coward | about a year and a half ago | (#43533411)

Didn't recognize the sarcasm before posting, did you?

Re:Looking forward to replacing a bulb... never (1)

Anonymous Coward | about a year and a half ago | (#43533035)

Talk to Milwaulke folks about using them in traffic lights. Problem is LED lights generate very little heat, so when winter blows snow into the light fixture, it just sticks there and doesn't melt off. Great for traffic snarls.

Re:Looking forward to replacing a bulb... never (1)

dbIII (701233) | about a year and a half ago | (#43533079)

The problem is some clown decided to replace just one part instead of doing a proper design that lets the snow fall out the bottom.

Re: Looking forward to replacing a bulb... never (1)

ceoyoyo (59147) | about a year and a half ago | (#43533163)

Speaking as someone from Canada... You guys must have done something wrong.

Re:Looking forward to replacing a bulb... never (1)

macraig (621737) | about a year and a half ago | (#43533107)

Roundabouts don't consume any power at all or require maintenance. Isn't that greener? Maybe we should be skipping the lights altogether and retrofitting roundabouts? Maybe next we can get rid of all the ubiquitous street lights, which are scarcely a longer blip in human history than automobiles and consume far more power than traffic signals?

Re:Looking forward to replacing a bulb... never (2)

Animats (122034) | about a year and a half ago | (#43533523)

If only they lasted. We've had LED traffic lights in areas of Silicon Valley for most of a decade, and many of them are failing, one section of LEDs at a time. There's a huge bin of partially failed traffic light round LED panels at Weird Stuff Warehouse in Sunnyvale. Mostly red and green; the yellows aren't on as much.

The problem is outright failure, not dimming. That's an indication of a manufacturing problem, like a joint that fails under thermal cycling. [imsasafety.org] Many pre-2004 LEDs are prone to this problem

we knew it was Auger (0)

Anonymous Coward | about a year and a half ago | (#43532541)

This has been ongoing debate for more than a decade but consensus was building up for a few years now that Auger was the one to blame. Still it's very nice to see a paper with a direct measurement.

Yes yes... (-1)

Anonymous Coward | about a year and a half ago | (#43532557)

Of course there will be lots of research.

The companies making light-bulbs have always been about us getting a better deal.
http://en.wikipedia.org/wiki/Phoebus_cartel [wikipedia.org]

They'll get around to that right after cures for cancer and aids.

BlaBla .. Blub!! - GaN excitation AUGER processes (-1, Flamebait)

burni2 (1643061) | about a year and a half ago | (#43532579)

Why writting so much dumpshit, we all know that LEDs are good for everything especially the money bags of those inventors and their masters (managers)

Please /. - kill those obvious advertisement or label these accordingly.

Re:BlaBla .. Blub!! - GaN excitation AUGER process (2)

Randle_Revar (229304) | about a year and a half ago | (#43532843)

It links to an .edu, ieee, and arxiv. It is not an advertisement, troll

But i like to dim my lights (2)

uberbrainchild (2860711) | about a year and a half ago | (#43532615)

Over here in sweden it's hard to find a good old light bulb that will dim. But I guess I can live with the non dimming led bulbs for now

Re:But i like to dim my lights (1)

Anonymous Coward | about a year and a half ago | (#43532767)

It's trivially easy to dim an LED, either reduce the voltage/current or pulse the DC

Re:But i like to dim my lights (0)

Anonymous Coward | about a year and a half ago | (#43532927)

If you look at the specs on most dimmable LEDs, the efficacy is much lower. The G7 Power 900 lumen, 9W bulb is well reviewed on Amazon. The G7 Power 830 lumen, 10W bulb is dimmable and newer technology if I read it right. That's a 20% loss. I assume the dimming circuitry is responsible for the loss. Am I right about this? If you put a PWM dimmer in your wall on the AC line, you can dim the bulb, but I assume the non-dimmable bulb would get a little upset. Is this because the driver for the non-dimmable bulb uses a single input comparator with a choke to limit the current? What is going on here?

Re:But i like to dim my lights (1)

Khyber (864651) | about a year and a half ago | (#43533055)

PWM is less efficient and stressful on the LEDs. It's simpler and easier to just use a potentiometer on the DC side of a constant-current driver to regulate current.

Re:But i like to dim my lights (1)

fuzzyfuzzyfungus (1223518) | about a year and a half ago | (#43533059)

When people say 'dim' they usually mean 'are compatible with my AC dimmer hardware designed to dim incandescents'. Given that any LED lamp designed to drop into an AC socket will need a reasonably sophisticated power supply(at least if it wants to actually be efficient, not catch fire, and not make the UL cry...), so the marginal cost of a slightly more sophisticated power supply that watches the AC side for 'dimming' behaviors and PWMs the DC side probably wouldn't be huge. However, such units are indeed less common, much as with CCFLs, which can be made to be dimmable with legacy AC dimmer gear; but cannot be relied upon to necessarily be dimmable, unless they specifically say so and aren't lying about it.

Re:But i like to dim my lights (1)

Osgeld (1900440) | about a year and a half ago | (#43533177)

most AC dimmers already pwm so its not that big of a deal for many

Re:But i like to dim my lights (1)

Anonymous Coward | about a year and a half ago | (#43532807)

There are dimming LED Light Bulbs.

Re:But i like to dim my lights (2)

AK Marc (707885) | about a year and a half ago | (#43532913)

I know. I bought a bunch of them from different stores/makers. They all flicker when powered in their listed range (0-12W dimmable DC). But the box clearly states "dimmable".

Re:But i like to dim my lights (1)

phantomfive (622387) | about a year and a half ago | (#43533179)

That's frustrating.

Re:But i like to dim my lights (2)

Osgeld (1900440) | about a year and a half ago | (#43533207)

the main problem with household LED lighting is they are made as stupid cheap as possible. I popped one apart and it was an LED, slug of god knows what metal and a big ass power resistor, nothing else

so you are using the diode part to block the negative ac waveform, already your LED is on only "50%" of the time, so directly out of the box its flickering at 30Hz, mess with that with a dimmer and it gets worse.

Re:But i like to dim my lights (1)

tftp (111690) | about a year and a half ago | (#43533353)

I know. I bought a bunch of them from different stores/makers. They all flicker when powered in their listed range

I have two dimmable 120V AC LED light bulbs. They do flicker at most levels. If you want a steady light, and not what one sees in horror movies, you have to set that dimmer to 100%.

The other reason for LED 'droop' (3, Funny)

Anonymous Coward | about a year and a half ago | (#43532649)

Yo, genius, you misread the resistor markings when you wired up your Arduino circuit.

Answer not in summary (5, Informative)

Anonymous Coward | about a year and a half ago | (#43532721)

It's because of Auger recombination. Basically, you stick in too many electrons, and they all mill around talking with each other instead of getting any work done. This is also known as the 'Water Cooler Effect'.

Re:Answer not in summary (1)

NoAnalogyGuy (2746401) | about a year and a half ago | (#43533029)

It's more like... uhm... OK, you know the... uh... Sorry. I had it for a minute, but it's gone now.

Re:Answer not in summary (1)

MatthiasF (1853064) | about a year and a half ago | (#43533181)

So, you're saying that instead of an electron falling into a hole causing a photon to be given off, the electrons are all huddled together elsewhere talking about the last episode of Big Bang Theory?

Re:Answer not in summary (1)

Paradise Pete (33184) | about a year and a half ago | (#43533615)

the electrons are all huddled together elsewhere talking about the last episode of Big Bang Theory?

Yes, they're talking about how the ridiculous audience laughter makes it unwatchable.

Re:Answer not in summary (5, Funny)

N Monkey (313423) | about a year and a half ago | (#43533627)

So, you're saying that instead of an electron falling into a hole causing a photon to be given off, the electrons are all huddled together elsewhere talking about the last episode of Big Bang Theory?

No. They'd be discussing "Quantum Leap"

Darn (0)

utkonos (2104836) | about a year and a half ago | (#43532755)

Everyone beat me to the Jigawatt joke.....

Re:Darn (5, Funny)

Anonymous Coward | about a year and a half ago | (#43532775)

Of course we would. We all have time machines.

Re:Darn (0)

Anonymous Coward | about a year and a half ago | (#43532931)

Jiga, whaaaat?

100 year life light bulbs is old tech (1, Offtopic)

NemoinSpace (1118137) | about a year and a half ago | (#43532895)

The ability of marketers to convince people to overpay for absolute garbage, is eclipsed only by people willing to work for peanuts in the middle of the night when they should be sleeping.

Re:100 year life light bulbs is old tech (0)

Anonymous Coward | about a year and a half ago | (#43533297)

The ability of marketers to convince people to overpay for absolute garbage, is eclipsed only by people willing to work for peanuts in the middle of the night when they should be sleeping.

Who's to say they're not sleeping too? They likely see you as some poor sap who sleeps for free.

Re:100 year life light bulbs is old tech (1)

mark_reh (2015546) | about a year and a half ago | (#43533341)

And "grades don't matter outside school" is what they tell dumb people while they are fitting them for work boots.

DOE Energy Frontier Research Center (2)

James Sneed (2846661) | about a year and a half ago | (#43532907)

Leave to our government to have a Department of Energy Energy Frontier Research Center. This just in from the Department of Redundancy Department we can reduce half the E from the DOE EFRC using LED's to become LEED certified says the CEEM.

Try the little blue ones (3, Funny)

Anonymous Coward | about a year and a half ago | (#43532919)

The little blue LEDs help me when I start to droop. Call your doctor if you don't stop drooping for more than two hours.

FucK a GNAA (-1)

Anonymous Coward | about a year and a half ago | (#43532937)

viS1t

The Color...Ugh (1)

Anonymous Coward | about a year and a half ago | (#43533015)

Is it me, or is the output color of household LED bulbs disgusting.
I've seen many different ones, and for some reason or another, to me they seem harsh on my eyes.
The incandescent ones seem warmer and friendlier to me.
Don't get me wrong, I'm no luddite. I'm all for saving energy, the environment, and stopping the flow of money to a55h0le muslim countries.
Does anyone else feel this way?

-HasHie @ irc.trypnet.net

Re:The Color...Ugh (0)

Anonymous Coward | about a year and a half ago | (#43533229)

one is a photon generator

the other is a ball of fire that happens to emit some photons, fire is natural, thus it seems easier on your eyes... I dont feel that way, the poor quality of light from a traditional bulb makes most things harder for me

Re:The Color...Ugh (4, Informative)

Arkh89 (2870391) | about a year and a half ago | (#43533305)

The white led are in fact blue LEDs with a phosphor layer which "shifts" the emission spectrum towards green and red. Thus, white LEDs looks bluer or "colder" (associated with ice). The bulbs can be considered as black bodies radiators and thus have their spectrum "coming from" the red part of the spectrum (in fact most of the energy is wasted in the IR as heat dissipation). Their color are more yellowish (centered on green, 550nm) just like the Sun and seems warmer (like a camp fire). Now you can combine few color LEDs to reproduce the the D65 illuminant (Black body at 6500K, like our Sun) by balancing the amount of current in them. Other trick : you reprogram your mind to follow "correctly" Wien's displacement law : blue color is for warmer black bodies compared to yellowish and reddish black bodies (thermal emission). To make sure of that : think of a metallic part you heat up, it will start as black (as in not-emitting) then go to red, then yellowish and then bluish (but you will see it white-blue at this point). So, white LEDs should appear "warmer" when considering true physics...

Re:The Color...Ugh (0)

Anonymous Coward | about a year and a half ago | (#43533571)

Very nice post Arkh89.
You are very right. Also blue stars burn hotter than yellow stars.
What i was trying to say was close to what the AC below me was saying, that the old bulbs are more like a fire, and to me have a more natural feel.
Its not that the blue/white LEDs are cold in terms of temperature, but in terms of emotion. They emit a precise almost digital output in contrast to a less precise analog output of the old bulbs. They even use DC instead of AC. So when I use the term warm, I use it in a way that one would describe a human being, as opposed to a cold calculating machine.
I feel like the precision of the LED's spectrum is burning my retinas, whereas the spread of the old bulbs, gives my retina a range that doesn't overwork anything specifically.
Might just be the LED's that I've seen, and that there are some really nice ones out there. Like you said, maybe all it needs is a mixing of diff LED colors or some getting used to.
When I switched from CRT to LCD monitors for my home computers, I definitely didn't like the LCD's at first.
TBH, i miss my CRT's even tho they were energy hogs, and didn't support the high resolutions of my current LCD's.
They also seem warmer and friendlier :)

Best Regards,
HasHie @ TrYPNET.net

Since my comment is in the other less-popular post (5, Interesting)

Khyber (864651) | about a year and a half ago | (#43533081)

Pay very close attention to LEDs. Now that we've identified the root cause of one of our biggest problems, in a few years, we'll find ways to work around those problems and extend the lifespan of an LED (and output at higher drive currents) with a minimal loss of light.

This is EXCITING news, as the uses for this across the entire electronics industry are MASSIVE. Higher-efficiency, longer-lasting LEDs means better optical devices and such, as this same tech can be applied down into solid-state laser diodes.

I'm literally about to piss myself from this news. The sheer implications of this knowledge are astounding.

I hope thermal pad and PCB makers are paying attention and prepare, because very soon we'll be pushing a LOT more power through these tiny LEDs, and we'll need the local cooling to compensate.

I only wonder just how far they can defeat or mitigate this effect, and how. Thicker well walls might be an idea, or perhaps a nano-wire-like growth pattern, like we've seen with the recent development of microwires on graphite sheets, can increase the surface area and reduce the available recombination area, thus forcing electron transport.

Something to either attract, guide, or force more electrons across the gap seems to be what is needed.

Re:Since my comment is in the other less-popular p (3, Insightful)

phantomfive (622387) | about a year and a half ago | (#43533205)

I'm literally about to piss myself from this news.

That's great, this is why I come here. What other site can you visit where people are more excited about a group of electrons than cute cats?

I'll bet right now you'd rather experiment with electrons than with sex.

Re:Since my comment is in the other less-popular p (-1, Flamebait)

Khyber (864651) | about a year and a half ago | (#43533347)

I had plenty of time working in a sex store, thank you. I probably know more about it than you ever will - just ask my husband.

Re:Since my comment is in the other less-popular p (1)

phantomfive (622387) | about a year and a half ago | (#43533369)

It's ok, you don't need to brag about it.

Re:Since my comment is in the other less-popular p (0)

Anonymous Coward | about a year and a half ago | (#43533587)

Did you forget where you are? You could have worked at the public library and it would be just as safe of a bet.

Re:Since my comment is in the other less-popular p (0)

Anonymous Coward | about a year and a half ago | (#43533351)

Hmmm... gotta think about this... Does the sex include a cute cate?

Re:Since my comment is in the other less-popular p (1)

phantomfive (622387) | about a year and a half ago | (#43533379)

It might include a crate.........

Where are these cute cats of which you speak? (1)

Brannon (221550) | about a year and a half ago | (#43533399)

Please be specific.

Re:Since my comment is in the other less-popular p (1)

Osgeld (1900440) | about a year and a half ago | (#43533239)

I got to play with some on the market now ceramic heatsinks that went though a reflow oven (~260c) and was able to be handled no problem the second it comes out (something you usually want to wear gloves for)

Re:Since my comment is in the other less-popular p (2)

Khyber (864651) | about a year and a half ago | (#43533391)

That 'ceramic' is still aluminum. Aluminum nitride and alumina mix, to be more precise

Re:Since my comment is in the other less-popular p (0)

OhANameWhatName (2688401) | about a year and a half ago | (#43533279)

This is EXCITING news

Damn, I ran out of troll points.

Another crap "summary" (2)

oldhack (1037484) | about a year and a half ago | (#43533127)

Basically, past a threshold current, it starts to emit electrons instead of more photons (look up "auger effect").

Thanks again to "editors", illiterate both in English and science.

Re:Another crap "summary" (0)

Anonymous Coward | about a year and a half ago | (#43533623)

Actually you are wrong, there is no Auger emission, but simply an Auger-like process whereby carriers are excited to hot states within the film.
Who's science illiterate now ;)

Cause of LED Efficiency Droop Finally Revealed... (1)

mooingyak (720677) | about a year and a half ago | (#43533433)

"We were just stepping out to grab a bite to eat," said one LED, who asked that he remain anonymous. "We didn't realize anybody could see a difference. Terribly sorry."

Cost Per Lumen? BS! (3, Interesting)

guttentag (313541) | about a year and a half ago | (#43533493)

The cost per lumen of LEDs has held the technology back as a viable replacement for incandescent bulbs for all-purpose commercial and residential lighting.

Really? CREE started distributing LED bulbs a month or two ago through Home Depot for less than $10 each. [theverge.com] I own two of them.

450 lumens for $9.97 is 0.0222 per lumen. It's rated to last 22.8 years. That's $0.0010 per lumen per year of use.

Let's compare that to an "equivalent" (the cree is a 40-watt equivalent bulb) incandescent bulb [homedepot.com] . $8.77 for a pack of 6 is $1.46 per bulb.

300 lumens for $1.46 is $0.0049 per lumen. But it's only rated to last 0.9 years. That's $0.0544 per lumen per year of use. It's more than 54 times more expensive than the CREE. That's before you look at the electricity you'll be saving (6 watts to get more light than you would out of a 40 watt incandescent).

Home Depot is also selling CREE's 60-watt equivalent:

800 lumens for $12.97 is 0.0162 per lumen.It's rated to last 22.8 years. That's $0.0007 per lumen per year of use. The incandescent is 77 times more expensive.

As much as I love CREE LEDs in general, I prefer Philips 10.5-watt bulb [philips.com] . The bulb itself it more aesthetically pleasing (in my opinion) and it diffuses the light better (the CREE focuses all the bulbs in one area and its very apparent from the very bright spot in the middle). I own six of them. Home Depot sells them for $27.97 for a two pack [homedepot.com] .

800 lumens for $13.99 is $0.0175 per lumen. Rated to last 18.3 years. That's $0.0010 per lumen per year of use. If I'm going to spent the next two decades with a bulb, I'll spend the extra three hundredths of a cent per lumen on something I really like. Still less than one fiftieth the cost of an incandescent per lumen.

The only things I see holding back LED bulbs are misinformation and lack of availability (Home Depot is the only major brick and mortar store I've found that carries them). That, and some freaky designs [philips.com] that don't look like light bulbs... I bought one of these out of curiosity, and its appearance, on or off, just irritates me for some reason... if I was redesigning my living room to look like Quark's, I'd go with these all the way, but since I'm not "that guy" it's in a lamp that I almost never use. Which means it will probably outlive me. It may even survive to the 24th century and end up in Quark's.

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