Organic light-emitting diodes based on charge-neutral Os(ii) emitters: generation of saturated red emission with very high external quantum efficiency

The OLED device using 6% of Os(fptz)2(PPh2Me)2 as the dopant emitter in a CBP host and BPAPF as hole transporting material shows an external quantum efficiency of 15.3% and luminous efficiency of 21.3 cd A−1, power efficiency of 6.3 lm W−1 at 20 mA cm−2. An even higher external quantum efficiency of ∼20% was achieved at a low current density of ∼1 mA cm−2.