Novaled, TU Dresden white OLEDs surpass fluorescent tube efficiency

May 15, 2009--The Technical University of Dresden (TU Dresden) and Novaled AG (both in Dresden, Germany) have reached 90 lm/W at a brightness of 1,000 cd/m2 for white organic light-emitting diodes (OLEDs), compared to the 50-70 lm/W of fluorescent tubes (considering losses in reflectors). Fluorescent tubes have been long considered a benchmark for emerging technologies.

May 15, 2009

2 min read

These ultra-thin large-area-emitting OLED devices can be flexible, transparent, color-tunable, and scaled to virtually any size or shape enabling completely new possibilities for display and lighting designers (see also "Metal-foil-backed OLED displays will soon be rollable").

"In our approach, we combine a novel, very energy efficient emission layer design with improved light outcoupling concepts, leading to this breakthrough," said project leader Sebastian Reineke, a physicist at the Institute of Applied Photophysics (IAPP, TU Dresden). "The power efficiencies of the record devices reach 90 lm/W even if only flat, scalable outcoupling techniques are used. With special 3D outcoupling measures, even 124 lm/W have been achieved." Both values were determined in an integrating sphere with blocked substrate edges, only taking the light into account that is emitted to the forward hemisphere; CIE color coordinates are (0.41/0.49). An in-depth article can be found in the journal Nature.

"The potential of the devices is obvious when one considers that even at the very high brightness of 5,000 cd/m2 a power efficiency of 74 lm/W is obtained," said professor Karl Leo, Director of IAPP. "Thus high-intensity illuminations at very high efficiencies are possible as well."

"These results are at R&D level and further developments need to be made, e.g. for reaching commercially acceptable lifetime," said Gildas Sorin, CEO of Novaled AG. "However, the values clearly indicate a major breakthrough and qualify OLEDs for mainstream lighting applications. The Novaled PIN OLED technology is crucial, especially for combining high efficiencies with high-brightness data. White OLEDs soon will help to reduce our carbon footprint and the Novaled doping technology will play a key role in this development," adds Sorin.

For more information, go to www.novaled.com.

--Posted by Gail Overton, [email protected]; www.laserfocusworld.com.