ILED wafers cannot be reused because the normal process is to saw apart the newly formed ILED crystals—while also cutting through the underlying wafer. (OLEDs have always been able to reuse their substrates, one of the reasons they have cost less than ILEDs.) After the ILED crystals have been separated they are picked up by a robotic device so they can be packaged, wired and used as tiles to make jumbotrons and other large, mostly outdoor displays. The robotic device is unable to pick up crystals that are smaller than about 100 microns per side, which prevents ILEDs from being made smaller.
The process that Rogers and his colleagues described in their research uses a different approach to cutting apart and transferring the ILED crystals. "We've found a way to take the inorganic material you grow on the wafer and embed a sacrificial base," he says. The researchers then make a lithographic imprint on the newly formed crystals. Instead of using a saw or a robotic "picker," the researchers use a rubber stamp to separate and lift the individual crystals—which in this new process can be as small as 20 microns on each side—so they can be arranged in tight arrays on glass, plastic, rubber or other surfaces. The underlying wafer can now be reused. (A micron is one millionth of a meter, or about 40 millionths of an inch.)
With this new process, the ILEDs can be interconnected, much the way OLEDs are wired, which saves space. "It's not the individual wiring that's done with ILEDs today," Rogers says.
It's unclear exactly how much of a cost difference there will be between OLEDs and ILEDs if they are used in comparable devices such as televisions or computer monitors. Even though ILEDs cost more to make, Kymissis says, "because they're so bright, you don't need as many."
Ford funded the research in part as a way to develop flexible lighting for vehicle interiors and brake lights, although, according to Rogers, it will be at least a couple of years before his team's technology would be ready for commercial use.
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Add CommentLEDs are the inexpensive energy-saving lights of the future. For several years we have all colors of LEDs out into the public domain, except inexpensive full spectrum white. Present LEDs for light bulbs available at about $10 & up depending on light level...price coming down fast. Most still use transformers but energy levels are around 4 watts for 60 watt equivalent and lifetimes of many thousands of hours....much longer life, more durable, half the wattage & better light balance, compared to the mercury-containing CFLs. Recent developments at Cambridge have produced inexpensive white light LEDs with no transformer, AC or DC use, and 110 or 220 volts. ,...especially useful for those off grid on solar and wind power. Even at $14 each, a local church is converting to the current white light LED recessed ceiling lights....one contribution at a time...
Reply | Report Abuse | Link to thisJames Beal
EMF Interface Consulting
Is there a spectral power distribution available for this device>
Reply | Report Abuse | Link to thisPete
Maybe we should be building houses with a low voltage power supply suitable for LED illumination. One more conductor and use the neutral line for return
Reply | Report Abuse | Link to thisThat picture is funny, it says "click to enlarge", but the new picture is actually smaller.
Reply | Report Abuse | Link to thisI always thought that the LED will be the future light source, it is very economical and use less electricity.
Reply | Report Abuse | Link to thisWith only a single ultra-bright white LED (3 watts) inside a small flashlight, this low energy consumption and highly emitting luminence flashligh that seems to be a useful toy for most people who need to walk in the darkness nights!
Reply | Report Abuse | Link to thisyes the 'bike lights' are the future, changes from metal halide and other flourescents are being made in many lighting applications.from flashlights to traffic lights, retail and residential this push for more and more sustainable options will lead to even more creative use. visual designers are replacing the colored gels for computer programmed LED effects proving more flexible and dynamic.. the latest home-ware sustainable option being the compact flourescent however given time i believe this will also turn electronic.
Reply | Report Abuse | Link to thisThe article doesn't talk about how to dissipate the heat from these new tiny LEDs. LEDs generate less heat for the amount of light they produce than other forms of lighting, but that heat is concentrated in a very tiny spot, sometimes requiring things like heatsinks to get rid of it. Will these new tiny LEDs be able to dump their heat somehow? The problem will become worse when those tiny LEDs are packed together in flat-screen displays.
Reply | Report Abuse | Link to thisCome to that, how do OLED displays dump their heat? Or is that an issue at all?
Lot's of interesting comments here. LED sources look very promising and they are approaching widespread viability very rapidly. They are not a panacea however. The best commercial white light LED's now offer about 40 lumens per watt and are very expensive compared to conventional sources. They are not viable in high wattage applications and most suffer color rendering indexes in the 70-80 CRI range and unfavorable monochromatic color temperatures. Fixture and lamp design is in it's infancy right now with many inelegant designs attempting to deal with the heat issue. But as many have stated, they are coming fast. They remind me of the first big screen TV's way before the flat screen revolution we have seen recently.
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