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Cause of LED Efficiency Droop Finally Revealed
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.
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.
Still waiting on Serviscope_minor to wake up to fucking reality and realize that Jessica Price isn't going to fuck him.
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. 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. $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. 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.
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 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.