Posted on 04/19/2006 10:57:35 AM PDT by Neville72
High efficiency flat light source could be the end for the light bulb
April 19, 2006 The end of the lightbulb is nigh! Scientists studying organic light-emitting devices (OLEDs) have made a critical leap from single-color displays to a highly efficient and long-lived natural light source. The invention is the latest fruit of a 13-year OLED research program led by Mark Thompson, professor of chemistry at USC and Stephen Forrest of the University of Michigan. If the device can be mass-manufactured cheaply - a realistic expectation, according to Thompson - interior lighting could look vastly different in the future. Almost any surface in a home, whether flat or curved, could become a light source: walls, curtains, ceilings, cabinets or tables. Since OLEDs are transparent when turned off, the devices could even be installed as windows or skylights to mimic the feel of natural light after dark - or to serve as the ultimate inconspicuous flat-panel television.
"This process will enable us to get 100 percent efficiency out of a single, broad spectrum light source," Thompson said.
Thompson and Forrest previously invented efficient single- color displays now ready to enter the market in next-generation cell phones. But subsequent attempts by several groups to create white-light OLEDs fell short. The biggest issue was the fast burnout time of the blue component, since blue is one of the primary colors needed to make white.
The Nature paper presents a quantum mechanical trick that solves this problem. First, the researchers followed their standard recipe for making an OLED: placing four ultra-thin organic layers on glass or transparent plastic. Three of the layers serve as highways for charges to reach a central "emissive" layer.
When the oppositely charged molecules meet in the emissive layer, electrons jump from the negatively charged molecules to the positive ones, and ultimately relax to their starting energy. In the process, light is emitted, which can be tuned to cover a broad range of wavelengths.
Previous OLEDs used phosphorescent blue, green and red dyes to generate light with greater energy efficiency than all-fluorescence based devices (phosphorescence and fluorescence, both expressions of energy that is released as excited electrons fall back into their regular orbit, differ mainly in the speed of their response).
Thompson and Forrest found that they could substitute a fluorescent dye for blue without sacrificing the superior properties of OLEDs.
In fact, the researchers reported, the fluorescent dye should prolong the lifetime of the blue component and also uses 20 percent less energy. "We're hoping this will lead to significantly longer device lifetimes in addition to higher efficiency," Thompson said.
According to Forrest, the device eventually could achieve three times the efficiency of standard incandescent light bulbs.
"With a future emphasis on manufacturing technology, this structure may provide an important, low-cost and efficient means that will replace incandescent lighting in many different applications," Forrest wrote.
The tallest remaining hurdle to production of these devices may have nothing to do with the OLED itself, Thompson said, but with the plastic layer to be used as a backing in economical large-area devices. All mass-produced plastics allow some humidity to pass through to the OLED, eventually degrading it.
"There's no plastic that's hermetic enough to make devices that will last a long period," Thompson said, while predicting that this problem can be solved. Already, Universal Display Corp. has developed the group's research into a commercially feasible process for making cell phone screens.
Funding for the research came from the Department of Energy and Universal Display Corp., which holds exclusive licensing rights to the group's OLED inventions.
There's other, IMO more significant advantages over fluorescent lighting- LEDs are far more durable and they do not contain mercury.
Yes, but will they make my glass Craftsman style lamps look good? That's my main question.
You can get similar products at computer stores- they plug into the computer's power supply.
An incandescent light bulb is more efficient as a heater than a lighter.
> 100 percent efficiency
I'm sure they meant to say 110 percent efficiency. :)
Your right if it were not for ben franklin we would still be watching tv by candle light.
These OLEDs are extremely efficient and it's possible that they are closer to 100% efficient than they are to 99% at converting electricity into the visible spectrum. However, it you want to be credible you need to specify the efficiency with enough decimal places to the point where we can see how much less it is than 100%.
It's possible that there's more loss in efficiency in the wiring that is going to the lamp than in the conversion to visible light, but I still want to see the numbers.
The real story here is a transformer that takes 5 volts DIRECT CURRENT to thousands of volts. Heretofore transformers have been Alternating Current only devices.
In traffic signals they also offer redundancy. If one LED in a signal array fails, the rest of them could still be working. With tradtional incandescent bulbs, if the bulb goes out the whole signal is out. A failure to show a red light, can be catastrophic for drivers through an intersection.
Wall sized UHDV screen... Oh my... Yummy.
It also makes a building's air conditioning system work harder to offset the heat produced by the lighting when cooling is needed.
This has a considerable potential to reduce the cost of installation, maintenance, and use. At the same time it adds a lot of options for making aesthetic improvements as well.
As long as you don't let the cat out of the box there is no inconsistency.
this is all very fascinating..... i converted to CFL's about a year ago & haven't had to change a bulb yet.
i'm imaginatively hopeful that eventually something similar to this product will cover all interior dwelling wall surfaces in replacement of paint. think of combining futuristic roll up plastic display screens for hdtv with the display changeability of a pc desktop. pc game 3d rendering
engines in conjunction with pc desktop customizability could produce the ultimate interior home decor device.
Two words: Nikoli Tesla.
You probably have that opinion because the good fluorescent lamps aren't usually available at your local hardware store.
Two thing to look for: Look for a lamp that scores at least 80% on the color rendering index. Also look for a lamp that is rated at least 5000 degree Kelvin on the color temperature index.
These minimal specs will give you a high quality color-corrected light. (If color rendering is important for your application, look for true "full spectrum" lamps: 91% CRI and 5900 degree Kelvin.)
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