Axially Chiral TADF‐Active Enantiomers Designed for Efficient Blue Circularly Polarized Electroluminescence. Issue 9 (24th January 2020)

• Record Type: Journal Article
• Authors: Li, Meng; Wang, Yin‐Feng; Zhang, Dongdong; Duan, Lian; Chen, Chuan‐Feng
• Is Part Of: Angewandte Chemie international edition. Volume 59:Issue 9(2020)
• Page Start: 3500
• Page End: 3504
• Publication Date: 2020-01-24
• Subjects: axially chiral enantiomers -- electroluminescence -- circularly polarized light -- organic light-emitting diodes -- thermally activated delayed fluorescence; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201914249
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: The use of a chiral, emitting skeleton for axially chiral enantiomers showing activity in thermally activated delayed fluorescence (TADF) with circularly polarized electroluminescence (CPEL) is proposed. A pair of chiral stable enantiomers, (−)‐( S )‐Cz‐Ax‐CN and (+)‐( R )‐Cz‐Ax‐CN, was designed and synthesized. The enantiomers, both exhibiting intramolecular π‐conjugated charge transfer (CT) and spatial CT, show TADF activities with a small singlet–triplet energy difference (Δ E ST ) of 0.029 eV and mirror‐image circularly polarized luminescence (CPL) activities with large g lum values. Notably, CP‐OLEDs based on the enantiomers feature blue electroluminescence centered at 468 nm with external quantum efficiencies (EQEs) of 12.5 and 12.7 %, and also show intense CPEL with g EL values of −1.2×10 −2 and +1.4×10 −2, respectively. These are the first CP‐OLEDs based on TADF‐active enantiomers with efficient blue CPEL. Abstract : Let's twist again : Axially chiral molecules with thermally activated delayed fluorescence and circularly polarized electroluminescence (CPEL) are presented. CP‐OLEDs based on these molecules display high efficiencies and blue CPEL with large g EL values.