Chiral Octahydro‐Binaphthol Compound‐Based Thermally Activated Delayed Fluorescence Materials for Circularly Polarized Electroluminescence with Superior EQE of 32.6% and Extremely Low Efficiency Roll‐Off

• Published in: Advanced materials (Weinheim) Vol. 31; no. 28; pp. e1900524 - n/a
• Main Authors: Wu, Zheng‐Guang, Han, Hua‐Bo, Yan, Zhi‐Ping, Luo, Xu‐Feng, Wang, Yi, Zheng, You‐Xuan, Zuo, Jing‐Lin, Pan, Yi
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01-07-2019
• Subjects: chiral octahydro‐binaphthol compound; Chirality; Circular polarization; circularly polarized organic light‐emitting diodes; Diodes; Efficiency; Electroluminescence; Enantiomers; Fluorescence; high efficiency; low efficiency roll‐off; Organic light emitting diodes; Photoluminescence; Quantum efficiency; thermally activated delayed fluorescence; Thin films; high efficiency; circularly polarized organic light-emitting diodes; thermally activated delayed fluorescence; low efficiency roll-off; chiral octahydro-binaphthol compound
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201900524

Circularly polarized organic light‐emitting diodes (CP‐OLEDs) are particularly favorable for the direct generation of CP light, and they demonstrate a promising application in 3D display. However, up to now, such CP devices have suffered from low brightness, insufficient efficiency, and serious efficiency roll‐off. In this study, a pair of octahydro‐binaphthol (OBN)‐based chiral emitting enantiomers, (R/S)‐OBN‐Cz, are developed by ingeniously merging a chiral source and a luminophore skeleton. These chirality–acceptor–donor (C–A–D)‐type and rod‐like compounds concurrently generate thermally activated delayed fluorescence with a small ΔEST of 0.037 eV, as well as a high photoluminescence quantum yield of 92% and intense circularly polarized photoluminescence with dissymmetry factors (|gPL|) of ≈2.0 × 10−3 in thin films. The CP‐OLEDs based on (R/S)‐OBN‐Cz enantiomers not only display obvious circularly polarized electroluminescence signals with a |gEL| of ≈2.0 × 10−3, but also exhibit superior efficiencies with maximum external quantum efficiency (EQEmax) up to 32.6% and extremely low efficiency roll‐off with an EQE of 30.6% at 5000 cd m−2, which are the best performances among the reported CP devices to date.
Octahydrobinaphthol‐compound‐based circularly polarized delayed fluorescence enantiomers, (R/S)‐OBN‐Cz are developed by merging a chiral source and a luminophore skeleton. The circularly polarized organic light‐emitting diodes based on (R/S)‐OBN‐Cz display intense CP‐electroluminescence signals with a |gEL| of ≈2.0 × 10−3, and achieve superior efficiencies with external quantum efficiency (EQE) up to 32.6% and extremely low efficiency roll‐off with an EQE of 30.6% at 5000 cd m−2.