The Technical University of Dresden and Novaled AG have reached 90 lm/W at a brightness of 1000 cd/ sq.m. for a "real lighting device" and 124 lm/W when using a 3D light-extraction system.
An in-depth article on the project, White organic light-emitting diodes with fluorescent tube efficiency, was published in the May 14 edition of Nature.
These white OLED ultra-thin large-area-emitting devices are flexible, transparent, color-tunable and scaled to virtually any size or shape, enabling new lighting design methods.
“In our approach, we combine a novel, very energy efficient emission layer design with improved light outcoupling concepts, leading to this breakthrough,” says project leader Sebastian Reineke, physicist at 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 has been achieved.”
Both values were determined in an integrating sphere with blocked substrate edges, only taking into account light emitted to the forward hemisphere with CIE color coordinates of (0.41/0.49).
“The potential of the devices is obvious when one considers that even at the very high brightness of 5000 cd/sq.m., a power efficiency of 74 lm/W is obtained,” commented Karl Leo, director of IAPP. “Thus high-intensity illuminations at very high efficiencies are possible as well.”
“These results are at an R&D level and further developments need to be made, e.g. for reaching commercially acceptable lifetime,” says Gildas Sorin, CEO of Novaled AG. “However, the values clearly indicate a major breakthrough and qualify OLEDs for mainstream lighting applications.
“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.