LEDs that convert heat directly into light...
 

http://physicsworld.com/cws/article/news/48882
For those of you in school, http://prl.aps.org/pdf/PRL/v108/i9/e097403

:O I don't know any quantum mechanics, but it is mindblowing to me that this LED is acting like a heat pump that is transferring heat energy directly to charge carriers.

Hopefully means a breakthrough in solid state cooling/power generation.

Are magnets involved?

Sorry Dimman, no they aren't.

Witchcraft or black magic? 200% efficiency???

I think I get it though (at least enough not to go looking for a torch and pitchfork). Normally we see heat emission as 'bad' or waste, but heat's just an IR photon, right? So this is just a visible photon instead, and since that is more useful to us it is 'good'? Something like that?

Still sounds like witchcraft...

Wow. That one lost me a little bit. Gonna have to read it again :D but very interesting

Sounds like whichcraft to me, First thing i thought was 2nd law of thermodynamics doesnt support this.

then they was like....NAH UH!

Then i was like...no shit? Are you wizard?

Then they explained their wizardry..

then i was like..

http://i31.photobucket.com/albums/c3.../Gifs/Epic.gif

I guess you can think of it as being analogous to a heat pump. If you have an air conditioner in your house, running it in heating mode (assuming it doesn't use a hot water radiator type thing) will give you 4-5 times as much heat as the electricity you put in.

With this, it's like a Peltier cooler, except somehow the light producing process is directly absorbing the heat (!)...usually if you're going to turn heat into visible light, you have to have it at a very high temperature. On top of that, thermoelectric devices have horrible efficiency, and LEDs aren't actually that great either (yet), so this black magic device that converts between the 2 can suddenly get apparently very high efficiency? WTF?
Darn, I better go take some quantum mechanics class sometime.

One of the thing I understand from this article is that there are some preserved energy phonon in the semiconductor lattice. Typically, this energy is stored somewhat like heat. In order to reach 200% efficiency, they have to tap into this stored phonon to generate photons. Now the question is, how do you get the phonon?

In the experiment condition they also heat up the LED to 135 degree C. This is very close to the maximum junction temperature of that LED, and thus they cannot put more bias voltage to it. That said, if the application is that we need to heat up the LED in order to get this 200% efficiency, we also need to consider how much heat that we have to submit to the LED for this to happen. Hmmm.. but, wait, I got a Core i7 that would be perfect candidate for the heating source. Problem solved!

Perfect... except for the fact that you'd need ~2x10^12 such LEDs to keep it from overheating :)

And to light up inside a computer box where no one will see.

Really cool stuff. I admit I'll probably have to read this several times.

oh shi-. Well guys, I figure I'll drive the FR-S for a solid five years then freeze myself when I'm 28 until full body prosthetics and cyber brains are invented. Then I'll live forever.

I saw an article on this the other day that didn't go into as much theoretical depth as this one, so thanks! Very very exciting innovation that seems like it could have a lot of applications down the road once they make further advances in the technology.