Naukowcy w USA zademonstrowali w praktyce układ w którym dioda LED zużywa 30pW prądu - i zmierzyli, że emituję energię (światło) o mocy 69pW...
pW to piko-wat, czyli jedna bilionowa wata (x10
-12).
A skąd się biorą dodatkowe 39 pW? To jest dobre - okazuje się, że dioda działa jako swego rodzaju ochładzacz - zbiera energię z naturalnych wibracji, będących skutkiem entropii w strukturach atomowych z których jest zbudowana.
Więcej szczegółów po angielsku.
LED's efficiency exceeds 100%
(PhysOrg.com) -- For the first time, researchers have demonstrated that an LED can emit more optical power than the electrical power it consumes. Although scientifically intriguing, the results won’t immediately result in ultra-efficient commercial LEDs since the demonstration works only for LEDs with very low input power that produce very small amounts of light.
The researchers, Parthiban Santhanam and coauthors from MIT, have published their study in a recent issue of Physical Review Letters.
In their experiments, the researchers reduced the LED’s input power to just 30 picowatts and measured an output of 69 picowatts of light - an efficiency of 230%. The physical mechanisms worked the same as with any LED: when excited by the applied voltage, electrons and holes have a certain probability of generating photons. The researchers didn’t try to increase this probability, as some previous research has focused on, but instead took advantage of small amounts of excess heat to emit more power than consumed. This heat arises from vibrations in the device’s atomic lattice, which occur due to entropy.
This light-emitting process cools the LED slightly, making it operate similar to a thermoelectric cooler. Although the cooling is insufficient to provide practical cooling at room temperature, it could potentially be used for designing lights that don’t generate heat. When used as a heat pump, the device might be useful for solid-state cooling applications or even power generation.
całość:
http://www.physorg.com/news/2012-03-efficiency.html
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