A phosphorescent OLED with an efficiency roll-off lower than 1% at 10 000 cd m −2 achieved by reducing the carrier mobility of the donors in an exciplex co-host system

A phosphorescent OLED with an external quantum efficiency of 22.31% and an extremely low efficiency roll-off of 0.67% at 10 000 cd m −2 was achieved by reducing the carrier mobility of the donors in an exciplex co-host system.