October 10, 2008

Small, Flexible OLEDs Could Replace Conventional Light Bulbs

Something's happening at General Electric Co.'s research campus in New York that could make nearly every household lamp obsolete. 

Inside the windowless industrial building is a semitrailer-sized machine that actually prints lights. The machine works by coating an 8-inch plastic film with chemicals and sealing it with a layer of metal foil. An electric current is then applied to the sheet that gives it a blue-white glow. 

These illuminated strips can then be placed on a wall or a window, or wrapped around a pillar to provide light.  And unlike nearly every other lighting source, the light strips would not require a lamp or other fixture, although an electrical outlet would still be needed.  

The sheets get their luminance from compounds known as organic light-emitting diodes, or OLEDs.  And while the technology is not yet perfected, it is far beyond the initial development stages.

Today, OLED's are starting to be used in cell phone displays and televisions, and companies such as Philips and Siemens are moving full steam ahead in implementing the new technology to make lighting sources.

In fact, GE's OLED printer was made on its sprawling upstate New York research campus, not too far from where a GE physicist figured out a practical way to use tungsten metal as the filament in conventional light bulbs.  Nearly a century later, those light bulbs are still widely in use today.

The incandescent bulb set the standard for home lighting with its small and bright form factor.  But because of their brightness they needed to be reflected and diffused with lampshades and frosted glass.  With OLEDs, all of that could change given their broad, diffuse light sources that provide more of a gentle glow.

The large glowing sheets could also make light sources out of everyday objects. For instance, GE imagines placing OLEDs on the inside of window blinds, or even making OLED wallpaper, both made possible by the material's flexibility.

"We have a lot of ideas for what we can do with it," Ingo Maurer, a German lighting designer, told the Associated Press.

He and his firm have already developed the first commercially available OLED lamp.  The firm is selling the lamp in a limited edition of 25, and Maurer expects to deliver the first two units this month at an undisclosed but likely collector-level price. 

At this stage, Maurer's lamp is more of a novelty than a practical lighting source.  The lamp is dim, growing slowly dimmer and losing half its brightness after about 2,000 hours.

The glass OLED panels in Maurer's lamp are made by Osram Opto Semiconductors, a subsidiary of Germany's Siemens AG, the parent of GE-competitor Osram Sylvania.

Osram Opto made the panels using a costly, time-consuming process known as vacuum deposition. One virtue of this method, which has dominated OLED development, is that it can be combined with technologies used in LCD displays to make full-color OLED TVs.   Sony Corp. currently sells an 11-inch model for $2,500.

But before OLED TVs can be mass marketed they must become larger and less expensive.  That's the issue GE hopes to tackle with its printer, which replaces vacuum deposition with a process that's not much more complex than the printing newspapers.

"We're trying to be as low-tech as possible," Anil Duggal, who leads GE's OLED research team, told the AP.

GE now plans to build a bigger machine for printing panels several feet wide.  According to Duggal, these large panels could become commercially available as early as 2010.    

However, initially small production runs would mean prices out of range for most consumers.  The luminous OLEDs could nevertheless be marketed for niche, luxury settings, such as casinos or upscale restaurants, where the OLED lights could help create striking architectural or artistic effects.

A few years from now, printing could reduce the OLED prices to little more than the cost of the material it's printed on, according to Janice Mahon, vice president of technology commercialization at Universal Display Corp. The Ewing, N.J-based company is a leader in OLED research, and develops some of the organic compounds, similar to the way dyes are used to color clothes.

If printed on metal foil, an OLED light would cost less than a dollar per square foot, according to Mahon.

This distinguishes OLEDs from inorganic LEDs, another promising technology often hailed as the future of lighting.  Inorganic LEDs, the tiny lights used in electronic gadgets, are beginning to be used in commercial lighting as well, where their extreme longevity compensates for higher production costs.  

Since inorganic LEDs are made through semiconductor manufacturing techniques, a cluster of LEDs producing light equivalent to that of a standard bulb can cost more than $100.

Although both LEDs and OLEDs offer the potential for significant energy savings compared with standard incandescent bulbs, matching fluorescents will be tougher.   This year Universal Display created OLEDs that exceeded the energy efficiency of fluorescents, but with some sacrifice in longevity. 

"It's not going to be competitive with fluorescents in 2010," Duggal said.

Nanomarkets LLC analyst Lawrence Gasman said LEDs would likely coexist with large, diffuse OLEDs. 

"Together, they make for a nice lighting future," Gasman told the AP, adding that OLED lighting sales could reach $5.9 billion by 2015.

However, not everyone shares Gasman's optimism.

Bob Sagebiel, technical marketing manager for lighting at distributor Arrow Electronics Inc., believes OLEDs may have a hard time gaining market acceptance because they are so different from current lighting technology.

For example, an OLED panel won't fit into any of the 20 billion light-bulb sockets in place throughout the world, he said.  And commercial buildings will likely need rewiring to use the large OLED panels, which won't fit into existing fluorescent tube fixtures.

Also, for companies such as GE and Osram to reach consumers, they'll need to first go through the makers of light fixtures, which Sagebiel called "an industry that is tremendously conservative".

Additionally, there are manufacturing issues to contend with, particularly in making OLEDs both long-lasting and power-efficient.    Since they gradually wear out with use, exposure to atmospheric oxygen can quickly destroy the panels.

But for all its challenges, OLED technology is better positioned to take on the lighting market than older technologies that produce thin, printable light sources.   Electroluminescent lights, used in Indiglo watches and car dashboards, have been around for decades but never become competitive in brightness or efficiency.

"In the 1950s, people were talking about electroluminescence the way we talk about OLEDs today," Duggal said.

"It's humbling."


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