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

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.

Stimuli‐Responsive Circularly Polarized Organic Ultralong Room Temperature Phosphorescence

“…Circularly polarized luminescence (CPL) from organic fluorophores,phosphors,orsupramolecular systems has been af ocus of burgeoning research in recent years. [1][2][3][4][5][6] Exponential attention has been paid to the design and fabrication of novel CPL-featured organic optoelectronic materials including fluorescence organic luminophores, [7][8][9] thermally activated delayed fluorescence molecules, [10,11] and metal-organic phosphorescent complexes. [12] Ther ecent development of room temperature phosphorescence (RTP) of purely organic materials,e specially organic ultralong RTP( OURTP) with lifetimes over 100 ms [13][14][15][16][17][18] has significantly shaped the understanding of organic optoelectronics.…”

Thermally activated delayed fluorescence material-sensitized helicene enantiomer-based OLEDs: a new strategy for improving the efficiency of circularly polarized electroluminescence

“…Recently, a new kind of chiral emitters with both thermally activated delayed fluorescence (TADF) and circularly polarized luminescence (CPL) properties have been developed [26][27][28]. Since we reported the first TADF-based CP-OLED with high EQEs in 2018 [29], the fabrication of CP-OLEDs by using chiral TADF molecules as the emitters has become a prospective strategy to obtain efficient CPEL [30][31][32][33][34][35]. However, the reported chiral TADF molecules were only used as emitters in the devices, and the emitters were also required to have small singlet-triplet gap (∆E ST ), large luminescence dissymmetry factor (g lum ), high racemic energy barrier and high mobility, simultaneously, which results in the difficulty of their design and synthesis.…”

Stimuli‐Responsive Circularly Polarized Organic Ultralong Room Temperature Phosphorescence

“…Circularly polarized luminescence (CPL) from organic fluorophores, phosphors, or supramolecular systems has been a focus of burgeoning research in recent years . Exponential attention has been paid to the design and fabrication of novel CPL‐featured organic optoelectronic materials including fluorescence organic luminophores, thermally activated delayed fluorescence molecules, and metal‐organic phosphorescent complexes . The recent development of room temperature phosphorescence (RTP) of purely organic materials, especially organic ultralong RTP (OURTP) with lifetimes over 100 ms has significantly shaped the understanding of organic optoelectronics .…”