SDK develops polymer-type OLEDs with 30 lm/W efficiency

July 29, 2009
A new phosphorescent polymer-type device structure improves light output and heat conduction.
Showa Denko K.K. (SDK) has developed a new OLED emitter structure that has enabled an efficiency of 30 lm/W, which is claimed to be the highest level announced for phosphorescent-polymer-based OLEDs.

SDK will continue working with SRI International, a non-profit research organization based in California, U.S.A., and Itochu Plastics Inc. (CIPS), of Japan, to promote the development of coated phosphorescent-polymer-based organic EL devices for early commercialization.

Small-molecule OLEDs are manufactured using deposition processes under vacuum. The technology is well-established but costs are high and there are many issues to be solved in producing a large area-emission panel based on this device.

Device structure However, the alternative approach being pursued by Showa Denko (and others) involves coating polymer layers without the use of vacuum, providing the opportunity for substantial cost reductions and for the production of large area-emission panels in the future.

Although fluorescent-type OLEDs have longer life, and are already used in displays of mobile phones, the alternative phosphorescent-type materials can theoretically have a four-times higher emission efficiency than the fluorescent type.

The new structure of Showa Denko’s OLED device features a layer of dielectric/heat conductor that helps to reflect light out of the structure, improving the light output, and also prevents heat deterioration of the emitter, prolonging the device life.

Alternative approaches SDK has already achieved a luminance half life of approximately 10,000 hours for white lighting through improvements in the phosphorescent-polymer materials. SDK will continue developing organic EL devices with longer life based on the successful development of the new device structure.

SDK says it will work with SRI International and CIPS to improve the design of device structure and start selling samples on a full scale in 2010 for use in the general lighting market. The three parties will also work to improve coating property of the phosphorescent polymer and prolong the device life, aiming to achieve a 150 lm/W emissive efficiency and a luminance half life of approximately 50,000 hours for white lighting by 2015.

SDK is planning to commercialize its coated phosphorescent-polymer-based organic EL devices for general lighting by achieving high levels of performance exceeding that of fluorescent lamps.