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

To 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 ?/Delta-Ir-(R-camphor) containing dual stereogenic centers at iridium and ancillary ligand, are efficiently synthesized. Benefiting from their high phosphorescence quantum yields (approximate to 93%) and obvious circularly polarized photoluminescence property with dissymmetry factors (|g(PL)|) 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 (EQE(max)) of 30.6%, low efficiency roll-off, and intense circularly polarized electroluminescence signal with dissymmetry factor (g(EL)) in the 10(-4) order of magnitude. By the novel device engineering with semitransparent cathode, the resulting g(EL) values are significantly boosted by one order of magnitude, up to 7.70 x 10(-3), which is the highest among the CP-OLEDs with chiral iridium complexes. Noteworthy, the semitransparent devices deliver a record-high EQE(max) 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.

Automated summary

This study successfully synthesized two green chiral iridium(III) isomers using R-camphor as a chiral resource, which exhibited excellent performance in circularly polarized phosphorescent organic light-emitting diodes. By novel device engineering, the dissymmetry factor of circularly polarized electroluminescence signal was significantly boosted by one order of magnitude.