Red phosphorescent organic light-emitting diodes based on a novel host material with thermally activated delayed fluorescent properties

Abstract

High cost of phosphors and significant efficiency roll-off at high brightness are the two main factors that limit the wide application of phosphorescent organic light-emitting diodes (PHOLEDs). Efforts have been paid to find ways to reduce the phosphors’ concentration and efficiency roll-off of PHOLEDs. In this work, we reported red emission PHOLEDs with low dopant concentration and low efficiency roll-off based on a novel host material 2,4-biscy- anophenyl-6-(12-phenylindole[2,3- a ]carbazole-11-yl)-1,3,5-triazine (BCPICT), with thermally activated delayed fluorescent (TADF) properties. The device with 1.0% dopant concentration displayed a maximum external quantum efficiency of 10.7%. When the dopant concentration was increased to 2.0%, the device displayed a maximum external quantum efficiency of 10.5% and a low efficiency roll-off of 5.7% at 1000 cd/m2.