Semitransparent Circularly Polarized Phosphorescent Organic Light‐Emitting Diodes with External Quantum Efficiency over 30% and Dissymmetry Factor Close to 10−2

Abstract

AbstractTo concurrently realize large electroluminescence dissymmetry factor and high device efficiency remains a formidable challenge in the development of circularly polarized organic light‐emitting diode (CP‐OLED). In this work, by introducing a famous chiral resource of R‐camphor, two green chiral iridium(III) isomers of Λ/Δ‐Ir‐(R‐camphor) containing dual stereogenic centers at iridium and ancillary ligand, are efficiently synthesized. Benefiting from their high phosphorescence quantum yields (≈93%) and obvious circularly polarized photoluminescence property with dissymmetry factors (|gPL|) in the 10−3 order of magnitude, the circularly polarized phosphorescent organic light‐emitting diodes using these chiral emitters show excellent performances with the maximum external quantum efficiency (EQEmax) of 30.6%, low efficiency roll‐off, and intense circularly polarized electroluminescence signal with dissymmetry factor (gEL) in the 10−4 order of magnitude. By the novel device engineering with semitransparent cathode, the resulting gEL values are significantly boosted by one order of magnitude, up to 7.70 × 10−3, which is the highest among the CP‐OLEDs with chiral iridium complexes. Noteworthy, the semitransparent devices deliver a record‐high EQEmax of 18.8% among the semitransparent OLEDs. The combination of novel chiral Ir(III) complexes and the semitransparent devices sheds light on the development of high performance CP‐OLEDs with simultaneously high efficiency and large dissymmetry factor.