LED backlights are displacing CCFLs application by application. That’s not to say that the end of CCFLs is anywhere in sight. LEDs and CCFLs will co-exist for the foreseeable future, but it’s the LED’s tentacles that are inserting themselves into more and more of CCFL’s territories; not the other way around. (If you would like to quantify this, and obtain cost models for LED and CCFL BLUs, I self-servingly recommend Insight Media’s 2008 Backlight Report.)

Ken Werner
Senior Analyst and Editor

Other backlight illumination technologies, including flat fluorescent lamps (FFLs), external-electrode fluorescent lamps (EEFLs) and hot-cathode fluorescent lamps (HCFLs), have been put forth and have more or less retreated. Field-emission technology may yet find a place in backlighting, perhaps using carbon nanotubes as emitters, but there are no commercial examples yet. Powder-based inorganic electroluminescent lighting is widely used for low-performance applications, such as wrist watches.

Is there a new backlighting technology peaking over the eastern horizon that could capture significant market share, at least in some applications? Yes. Possibly.

In its recently published report "OLED Lighting Markets — 2008," NanoMarkets predicts the OLED backlighting market will reach US$1.1B by 2015. Now, you certainly have a right to be skeptical of any 7-year prediction, but that won’t stop me from relaying the rest of it. NanoMarkets also predicts the general illumination market for OLEDs will be US$2.3B by 2015.

Although OLED displays have kick-started the technology, it is general illumination that will eventually drive the development of OLED lighting, and backlighting will benefit. Solid state lighting (SSL), which includes both LEDs and OLEDs, is generating a lot of interest and investment because it’s an energy-saving technology that also offers exciting new ways to produce and package light. LEDs are much closer to being point sources of light than incandescent or fluorescent lamps, and OLEDs can be made as flat (or curved or flexible) extended sources, opening the possibility of walls, ceilings, and floors that are also sources of light.

LEDs have a substantial lead on OLEDs in terms of technology development and commercialization. LEDs have considerably higher efficiency right now, but OLEDs have the potential for matching it. NanoMarkets quotes a DOE report that projects OLED lighting will reach a luminous efficiency of 150 lm/W in 2012, two years earlier than previously forecast. LED lifetime is also greater at 50k to 100k hours for many commercial products, but OLED is improving rapidly. According to NanoMarkets, OLED lifetime increased to 100k hours from 24k hours in 2008, but the company did not identify the OLED material and device structure to which it was referring. (Makers of OLED displays would kill for a suitable RGB phosphor set with 100k-hour lifetime.)

OLED lighting panels — or lighting sheets — could conceivably be made with a combination of roll-to-roll processing (demonstrated by GE and the Fraunhofer Institute), some version of the DuPont/Dainippon Screen spray printing process, or slot coating. This could reduce cost. It would certainly produce flexible lighting sheets of arbitrary length, which would excite designers and architects.

But to obtain adequate luminance and efficiency when OLEDs are used as backlights for large LCDs, it may be necessary to stack transparent OLEDs two or three deep. That, of course, would add to the cost. For the foreseeable future, even one-deep OLED lighting will come with a significant cost premium, just as OLED displays do, and the initial applications will be those where the unique characteristics of OLED lighting add enough value to justify that cost.

Even with all these qualifications, the next big backlight technology could be OLED — at about the same time my 401K recovers most of its value.