High-performance yellow- and orange-emitting diodes based on novel sublimable cationic iridium(iii) complexes by ligand control

Abstract

We have devised a series of novel sublimable cationic iridium(III) complexes by ligand control, investigated their photophysical properties, electrochemical behaviours and thermal stabilities, and then fabricated vacuum-evaporated-deposited organic light-emitting diodes. By doping these cationic iridium(III) complexes into a thermally activated delayed fluorescence bipolar host material at very low concentrations of 1 or 2%, we have achieved high-performance yellow- and orange-emitting diodes with peak external quantum efficiencies of 13.7 and 10.3%, respectively. All the devices show maximum luminance exceeding 27.3 × 10³ cd m⁻² and low turn-voltages varying from 2.2 to 2.5 V. To our knowledge, these values are the record performance of analogous devices based on cationic iridium(III) complexes, indicating their great promise as phosphorescent emitters for flat-panel displays and solid-state lightning techonology.