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 day. 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.
Back in 2010 Universal Display said that NEC were using their PHOLED materials in protoype OLED lighting panels, and it's highly likely that those new OLEDs are phosphorescent based, too.
Source: TechOn