Panasonic Electric Works announced that they developed a new highly efficient OLED device - featuring 128 lm/W efficiency. This was achieved using a semi-spherical highly-refractive lens to enhance light extraction. The OLED panel is small - only 2x2 mm, and according to Panasonic this is the world's most efficient white OLED.
PEW says that in order to achieve this high efficiency, they inserted a light extraction layer composed of a highly-refractive material between the emissive layer (EML) and the glass substrate. The back side uses a high-reflectivity metal material. Detailed calculations were performed to minimize the internal reflection - this doubled the light extraction efficiency to 40%. This panel uses all-phosphorescent materials, and PEW says that this technique is actually similar to the technique used by Universal Display when they developed the 102 lm/W device back in 2008.
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