Axially Chiral TADF-Active Enantiomers Designed for Efficient Blue Circularly Polarized Electroluminescence

Meng Li; Yin-Feng Wang; Dongdong Zhang; Lian Duan; Chuan-Feng Chen

doi:10.1002/anie.201914249

Axially Chiral TADF-Active Enantiomers Designed for Efficient Blue Circularly Polarized Electroluminescence

Angew Chem Int Ed Engl. 2020 Feb 24;59(9):3500-3504. doi: 10.1002/anie.201914249. Epub 2020 Jan 24.

Authors

Meng Li^{1

2}, Yin-Feng Wang^{1

2}, Dongdong Zhang³, Lian Duan³, Chuan-Feng Chen^{1

2}

Affiliations

¹ CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
² University of Chinese Academy of Sciences, Beijing, 100049, China.
³ Department of Chemistry, Tsinghua University, Beijing, 100084, China.

PMID: 31872521
DOI: 10.1002/anie.201914249

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 (ΔE_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.

Keywords: axially chiral enantiomers; circularly polarized light; electroluminescence; organic light-emitting diodes; thermally activated delayed fluorescence.

Abstract

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