An ethylcarbazole based phosphine oxide derivative as a host for deep blue phosphorescent organic light-emitting diode

Deep blue phosphorescent organic light-emitting diodes (PHOLEDs) were developed using a 9-ethylcarbazole based phosphine oxide material (EPO1). A high triplet energy of 3.01 eV was obtained from the EPO1 host material and efficient energy transfer from the host to the deep blue emitting phosphorescent dopant was observed. A high quantum efficiency of 7.9% with a color coordinate of (0.15, 0.17) was achieved in the deep blue PHOLED using the EPO1 host material.