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

Abstract

Abstract 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 Δ E ST of 0.037 eV, as well as a high photoluminescence quantum yield of 92% and intense circularly polarized photoluminescence with dissymmetry factors (| g PL |) 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 | g EL | of ≈2.0 × 10 −3 , but also exhibit superior efficiencies with maximum external quantum efficiency (EQE max ) 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.