Cohosts with efficient host-to-emitter energy transfer for stable blue phosphorescent organic light-emitting diodes

We present a high-performance blue phosphorescent organic light-emitting diode exhibiting a low operating voltage (4.1 V), high external quantum efficiency (23.4%, at 500 cd m −2 ) with a low efficiency roll-off (4.7%), and a long operation lifetime (time at which the luminance reaches 95% of its initial value, LT95 = 232 h).