OLED Breakthrough at U. of Michigan and Princeton: 70 Lumens/Watt!
by Michael Graham Richard, Gatineau, Canada on 07.25.08
Paradoxically, technology both moves very fast yet more slowly than we sometimes wish. New things are coming out all the time (like this big LED breakthrough from Purdue and telescopic pixel screens), but we get used to them so fast that we're always looking ahead and it never seems to get there fast enough. It was only a few months ago that we wrote about a big organic light-emitting diode (OLED) breakthrough by Osram who had succeeded in making OLEDs that produced 46 lumens per watt.
Better OLEDs!
Now researchers at the U. of Michigan and Princeton are saying they made OLEDs that can produce 70 lumens per watt (compared to 15 lumens per watt for incandescent), and that they might be able to do even better than that. To achieve that impressive efficiency, they are using a grid combined with micro-lenses, all of it on the nano-scale (the lenses are 5 micrometers wide).
OLED Breakthrough Technical Details
In OLEDs, white light is generated by using electricity to send an electron into nanometer-thick layers of organic materials that behave like semiconductor materials. Typically, the light in the substrate is internally reflected and runs parallel and not perpendicular. That's the crux of the problem because the light can't escape in the vertical direction without some coaxing. In Forrest's devices, the grids refract the trapped light, sending it to the five micrometers dome-shaped micro lenses. The light is sent off in a vertical orientation that helps release the trapped rays.
Benefits of OLEDs
A little while ago, Collin wrote a little primer on LED and OLEDs. If you are curious about the benefits of this technology from a green perspective, check out his post LED and OLED Home Lighting Systems Almost Ready for Prime Time. There's also HowStuffWork's article on OLEDs.
You can also read about Osram's OLED research in this post: Osram Claims Warm White Organic LED Breakthrough.
The bottom line is: Better and cheaper OLEDs can mean greener flat screens and light sources.
LED, OLED, Lights
Big LED Breakthrough at Purdue University Could Change the World
GE "major milestone": Printing Organic LEDs like Paper, Applicable to Solar Panels
Osram Claims Warm White Organic LED Breakthrough
More on OLED Breakthrough
More-Efficient OLED Lighting
Can't wait to have OLED screens. Would be nice to have lights too. maybe really big diffuse sources to simulate the sun?
I wonder if the same kind of techniques can be used to make other kinds of LEDs better. Microlenses on regular LEDs? Hmm.
I love the image quality achieved by today's inefficient plasma displays but once this tech becomes feasible for the regular consumer, my heart will no longer have to ache at the power usage of flat panels.
Sony has already released the first consumer OLED screen (the XEL-1). At $2500 it's a bit unreachable right now. Only 3mm thick, it's almost magic to look at.
TV's will be a hard market for OLEDs to crack. You will see them in smaller, more "disposable" electronics such as cell phones much sooner (Indeed, they are already out there). The reason for this is OLEDs Achilles heel - the stability of the chemical which emits the blue light. Blue light is higher energy than green or red, so whichever chemical emits blue gets stuck with the honor of doing the most work, and craps out sooner. Hence, the color accuracy tends to drift. While this is fine for a device that is on maybe one hour a day (such as a phone screen) it is not fine for one which is on many hours a day, such as a computer or tv screen. Nobody has really solved this problem yet, though it is incrementally getting better.
No thanks; my full-size 5000 K flourecents stay until they can offer them in a colour I can stand.
Hold your horses.
First of all, Lumens are not a reliable way of measuring efficiency in conversion of electricity to light.
Lumens only measure how bright "you feel" the light is. Lumens are a visiometric unit for light brightness.
Seconly, 70 lumens per Watt has been achieved with fluorescents many, many years ago. It is nothing to write home about - even if it might be a major OLED-tech leap forward, it still means OLEDs are not yet competing with fluoros, even!
Csmr
Hold your horses.
First of all, Lumens are not a reliable way of measuring efficiency in conversion of electricity to light.
Lumens only measure how bright "you feel" the light is. Lumens are a visiometric unit for light brightness.
Seconly, 70 lumens per Watt has been achieved with fluorescents many, many years ago. It is nothing to write home about - even if it might be a major OLED-tech leap forward, it still means OLEDs are not yet competing with fluoros, even!
Csmr
70 is a breatthrough for OLEDs only. Luxim is at 140 with their plasma lighting and it is 6000k color so full spectrum.
Good luck beating that one.