A Japanese research team developed a phosphorescent material that emits a blue light, has a high external quantum efficiency of 30% and can be driven with a low on-state voltage of 2.5V.
The team is led by Junji Kido and Hisahiro Sasabe, professor and assistant professor, respectively, at the Department of Organic Device Engineering, the Graduate School of Science and Engineering, Yamagata University. A thesis about the material was published on the June 27, 2014 issue of the Advanced Materials magazine.
The emission wavelength of the new material peaks at 474nm (band gap: 2.62eV). Also, the reduction in quantum efficiency in a high-brightness area (roll-off) is small. The external quantum efficiency of the material becomes 30% when its brightness is about 100cd/m2. But even when its brightness is 10,000cd/m2, its external quantum efficiency is 20%, the research team said.