New LED that's over 100% efficient but doesnt break any laws - Page 1
Forum section: electronics / general

author: Psi
author_rank: Super Contributor
timestamp: March 08, 2012, 11:09:48 pm
content: http://dvice.com/archives/2012/03/230-efficient-l.php"When the LED gets more than 100% electrically efficient, it starts to cool itself down, which is another way of saying that it's stealing energy (in the form of heat) from its environment and converting that heat into those over-unity photons."Don't get your hopes up though, it currently only works at 69 picowatts

author: ron
author_rank: Regular Contributor
timestamp: March 08, 2012, 11:38:50 pm
content: "LED that produces 69 picowatts of light while using just 30 picowatts of power."Sounds like it might be a more efficient cooling device than light emitter.

author: AntiProtonBoy
author_rank: Frequent Contributor
timestamp: March 08, 2012, 11:41:55 pm
content: Very interesting, more so for the potential of creating a new type of thermal imaging devices. If the heat influences the brightness of these LEDs, then I'd imagine you could create a LED matrix, focus infra-red light on them, and potentially form an image in visible light. For example, you can use a CCD with these LEDs deposited on top of each CCD pixel. Then use image processing to detect brightness fluctuations, etc.

author: amspire
author_rank: Super Contributor
timestamp: March 08, 2012, 11:47:23 pm
content: I want to know how do you accurately measure that a LED is emitting 69 picowatts of light. It wouldn't be hard to make an error.

author: 8086
author_rank: Super Contributor
timestamp: March 08, 2012, 11:55:33 pm
content: So, does it just not put out as much heat, plateau, or does it actually get cold after you reach 100%?

author: ron
author_rank: Regular Contributor
timestamp: March 09, 2012, 12:04:01 am
content: Here's a little more info:http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.108.097403

author: AntiProtonBoy
author_rank: Frequent Contributor
timestamp: March 09, 2012, 12:13:32 am
content: Quote from: amspire on March 08, 2012, 11:47:23 pmSome photomultiplier tubes and avalanche photodiodes can detect light at one photon at a time if you are so inclined.

author: Zad
author_rank: Super Contributor
timestamp: March 09, 2012, 12:39:21 am
content: It is certainly possible to get cooled CCDs to detect single photons and measure the energy levels.This seems to be what is basically a Peltier/Seebeck module with the output being photons rather than heat.

author: damo
author_rank: Contributor
timestamp: March 09, 2012, 03:16:51 am
content: Quote from: Dave.S on March 09, 2012, 02:02:10 amAgreed, but what do you mean by laws of percentage?So it operates in an open system with external heat energy being converted to photons. This means that the device is operating at less that 100% efficiency, but has a COP of 2.3. Not impossible considering the heat exchangers and compressor in a heat pump operate at less than 100% efficiency, but the heat pump generally operates at COP's above 1.

author: IanB
author_rank: Super Contributor
timestamp: March 09, 2012, 03:48:58 am
content: Quote from: amspire on March 08, 2012, 11:47:23 pmOne way would be to create an array of 10^12 devices and check that they emit 69 watts of light when supplied with 30 watts

author: SoftwareSamurai
author_rank: Regular Contributor
timestamp: March 09, 2012, 03:49:25 am
content: Scientists do use lasers tocool downthings. I know, it's counter-intuitive, but it's true. So I can totally believe that at a certain level an LED could cause a cooling effect. I would, however, like to see them repeat this particular experiment and collect temperature readings of the diode and the ambient environment for a long time. That would be interesting.

author: BravoV
author_rank: Super Contributor
timestamp: March 09, 2012, 04:48:32 am
content: Now I want my flashlight that can be strapped to a can of beer, a bright portable fridge folks !!

author: vk6zgo
author_rank: Super Contributor
timestamp: March 09, 2012, 04:54:31 am
content: I think it is the substance horses leave behind!

author: Pentium100
author_rank: Frequent Contributor
timestamp: March 09, 2012, 05:34:52 am
content: Quote from: damo on March 09, 2012, 03:16:51 amWell, the wall (or whatever) hit by the light warms up, so the total amount of heat increases. It will be intersting to see if they can scale these devices up to, say 1W or more.

author: amspire
author_rank: Super Contributor
timestamp: March 09, 2012, 07:13:43 am
content: Apparently they made a special low bandgap LED with about a 1mW light output when the power in was about 100mW. So that is a 1% efficient LED. Normal LEDs have efficiencies of about 4% to 18%, so this is a pretty useless LED for practical uses.They then heated it to 135 deg C and lowered the electrical power down to 30 picowatts. It emitted 69 picowatts of light, so by calculation, it must have cooled the LED at about 40 picowatts. They claim a 230% electrical efficiency (ignoring the heat energy they are pumping into the LED). Way to low an effect to detect thermally. At 85 degrees, the efficiency only reached about 10% at 30 picowatts, and at room temperature, it had fallen to about 0.1% at 30 picowatts.Sounds like the idea is a huge way from being a useful technology. By pumping in lots of heat, they were able to get an unmeasurable cooling effect at nearly unmeasurable power levels. I think to get any kind of useful effect, a far higher temperature is needed.Richard.

author: Hypernova
author_rank: Unknown
timestamp: March 09, 2012, 02:20:30 pm
content: If they can get this going it may work as part of the LED drivers cooling system, by dumping part of the waste heat as part of you target output you can save on the big ass heat sinks.

author: sacherjj
author_rank: Frequent Contributor
timestamp: March 09, 2012, 02:48:45 pm
content: So for tens to hundreds of Watts of heatand 30 picowatts of electrical power, they get 69 picowatts of light.

author: T4P
author_rank: Super Contributor
timestamp: March 09, 2012, 05:05:24 pm
content: Quote from: sacherjj on March 09, 2012, 02:48:45 pmAnd we try to wonder and think are theytheoretical scientistsor actual engineers

author: AntiProtonBoy
author_rank: Frequent Contributor
timestamp: March 10, 2012, 12:16:08 am
content: Some of you are missing the point. The experiment was done in order to provide empirical evidence for a theory related to semiconductor physics, not to provide a practical solution for a particular problem.

author: amspire
author_rank: Super Contributor
timestamp: March 10, 2012, 12:49:33 am
content: Quote from: AntiProtonBoy on March 10, 2012, 12:16:08 amThe researchers are actually promoting this idea as having the potential to be useful in the future, and the truth is, they are an extremely long way from that goal right now. It is not just abstract research to prove a theory.At the moment, at 30pW, only something like one in a thousand electrons flowing into the device are triggering light, so according to the theory, 99.96% of the emitted light is coming from the vibrational energy of the crystal lattice. I cannot help wondering if they could make a material that could emit light from thermal energy without needing any electricity. Or could you get some kind of chain reaction point where the amount of electricity that gets generated by the re-absorbtion of some of the generated light is enough to sustain the conversion process? So all you need is to expose a panel to light to start it converting heat to light, and then it does it on its own continuously from there. The only way to shut it down is to let the panel cool till it stops.Richard.

author: AntiProtonBoy
author_rank: Frequent Contributor
timestamp: March 10, 2012, 07:26:58 am
content: Quote from: amspire on March 10, 2012, 12:49:33 amUnfortunately, the research paperis behind a pay wall, so I don't know for sure whether they are promoting anything. I didn't see it that way though, and I certainly take second hand reporting on these topics with a grain of salt.QuoteUp-converting phosphors certainly do exist . From memory, some phosphors had excitation wavelengths in the vicinity of 1000 nm, and peak emission around ~600 nm (I can't remember exact figures), which in itself was pretty cool. I'd imagine shifting the excitation response into the thermal range is not a trivial exercise. At any rate, I don't know enough on the topic to comment anything more insightful. I just hope this tech will open up new avenues in light emission research.1. Yamamoto et al., Phosphor Handbook, CRC Press, 2007

author: Bored@Work
author_rank: Super Contributor
timestamp: March 10, 2012, 09:31:40 am
content: Quote from: amspire on March 10, 2012, 12:49:33 amOf course they do, they need funding.

author: Unknown
author_rank: Unknown
timestamp: March 10, 2012, 12:00:00 pm
content: The authors do hint at it:QuoteThe new discovery is not so much the conversion of heat to light, but that the cooling power is more than the heating (loss) caused by inefficiency, hence the claim that the efficiency is > 100%.Quote from: amspire on March 10, 2012, 12:49:33 amThe semiconductor junction needs to be biased, so I don't see it happening without electricity. Bias voltage was about 70 µV in this case, hence the extremely low power.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 10, 2012, 03:51:28 pm
content: ok, put 15 billions of em side by side. then we'll get 1W of light from 0.43W of psu, and nice airconditioning effect

author: Zero999
author_rank: Super Contributor
timestamp: March 10, 2012, 07:28:41 pm
content: QuoteSo they're claiming it's not breaking the first law of thermodynamics but the second? It's still total bollocks. Heat naturally flows from a hotter place to a cooler one, to get it to flow in the opposite direction requires a heat pump which needs energy.

author: Unknown
author_rank: Unknown
timestamp: March 10, 2012, 08:02:40 pm
content: Did you actually read the article before claiming people published in Phys. Rev. Lett. don't understand basic physics? For a theoretical background, seethis(probably also behind a paywall, go shoot the publishers, not me). The short version: the entropy of incoherent light far below the lasing threshold is higher than that of the semiconductor lattice, so the emitted photons can extract up to the difference in entropy of energy (T*S) from the lattice without violating the second law of thermodynamics.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 11, 2012, 01:34:28 am
content: Quote from: Dave.S on March 10, 2012, 04:48:53 pmno i mean using 1nm technology.

author: amspire
author_rank: Super Contributor
timestamp: March 11, 2012, 12:23:14 pm
content: Quote from: Dave.S on March 11, 2012, 10:38:32 amI cannot see the purpose of using a small geometry. The test was done with a pretty large led, and they were emitting something like 200 million photons per second. A 1nm geometry would currently emit something like one photon per hour.Even if they improve the efficiency a million times, a 1nm led would still be useless. You would want huge led junctions.Richard.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 11, 2012, 02:30:17 pm
content: Quote from: amspire on March 11, 2012, 12:23:14 pmman! lets take practicality into calculation. say "they" are able to remove that plastic covering and mould into one (for all leds), say 3mm apart. 15bils is 122.5Kled square = 368m.sq, not too bad! what is it like? 2 football field? for 1W led? well, a PC once the size of a big room. i think we are getting there/somewhere(ps: dont take it seriously, i'm not scientist)

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 11, 2012, 03:20:54 pm
content: Quote from: Dave.S on March 11, 2012, 02:38:17 pmhow do you get that? or maybe your arrangement is not optimum. i'm talking 2D array arrangement hort & vert like camera sensor. sqrt(15bils) = 122.5K led each dimension. 1nm (1e-9m) apart eqv 122.5K x 1e-9m = 0.1225mm.sq. 32nm? 3.92mm.sq! (eqv to 1 normal sized led!) but again, our Mr Richard postulates of its impossibility.

author: Zero999
author_rank: Super Contributor
timestamp: March 13, 2012, 09:19:32 am
content: Quote from: alm on March 10, 2012, 08:02:40 pmAll I read was the original link posted at the star of the thread and the link you've posted isn't much better.Is there more to this?From what I've read so far it looks like rubbish.

author: Unknown
author_rank: Unknown
timestamp: March 13, 2012, 10:43:08 am
content: The link posted by AntiProtonBoy and its references, for starters. What part of the article I referred to do you disagree with? It's not my area of expertise, but once you accept equation (2), which essentially represents the Boltzmann distribution, the rest, like eq. (2a), appears to be fairly straightforward physics.As for the practical applications, I wouldn't hold by breath and consider this purely fundamental physics research for now.