NEC Lighting developed the world's most efficient OLED device at 156 lm/W
NEC Lighting announced that they developed a new OLED lighting device that has an efficiency of 156 lm/W - that's the world's most efficient OLED to date. This device was co-developed with Yamagata University's research group led by Junji Kido. You can see Professor Kido's work in the video below (from 2011):
The device is 2x2 mm in size and the brightness is 1,000 cd/m2. NEC said that the emitter materials were developed in the Kido Lab of Yamagata University. Unfortunately NEC did not reveal the structure and technologies used to fabricate this OLED.