Quinazoline-based thermally activated delayed fluorescence emitters for high-performance organic light-emitting diodes with external quantum efficiencies about 28%

Abstract

Incorporating both preferential orientation of organic emitters in the emitting layer and high photoluminescence quantum yield (PLQY) is a challenging issue in the organic light-emitting diode (OLED) field. In this study, a green thermally activated delayed fluorescence (TADF) emitter 10-(4-(2-(3,5-di(pyridin-2-yl)phenyl)quinazolin-4-yl)phenyl)-10H-phenoxazine (2DPyPh-Qz) containing two 2-pyridyl groups to give both preferential emissive dipole orientation and high PLQY was developed based on a phenoxazine electron donor segment and a quinazoline electron acceptor segment. This new emitter has a higher horizontal dipole ratio of 79% and a higher PLQY of 96% compared to the reference emitter when doped in a host film. OLEDs fabricated with this emitter achieved good external quantum efficiency of ∼28% and current efficiency of 89.9 cd A⁻¹, which are competitive figures among quinazoline-based TADF emitters.