Circularly Polarized Electroluminescence of Thermally Activated Delayed Fluorescence-Active Chiral Binaphthyl-Based Luminogens

Two pairs of thermally activated delayed fluorescence (TADF)-active chiral luminogens ( R / S -1 and R / S -2) can be achieved by introducing D–A-type groups to chiral BINOL skeletons. The resulting chiral luminogens can exhibit aggregation-induced emission properties in THF–water mixtures and TADF emission in a doped-film state. The absolute photoluminescence quantum yield (Φ PL ) and delayed fluorescence lifetimes (τ delayed ) were measured to be 18.5% and 1.03 μs for R -1 and 15.7% and 0.97 μs for R -2. However, only R / S -1 with the fixed conjugation structure can emit circularly polarized luminescence signals, and g lum can reach 1.6 × 10 –3 in toluene solution and 9.2 × 10 –4 in the neat film. Most importantly, R / S -1 was chosen as the emitting layers for orange-red circularly polarized organic light-emitting diodes, which can display low turn-on voltage ( V on ) of 3.4 V, high maximum brightness ( L max ) up to 40 470 cd m –2, moderate external quantum efficiency of 4.1%, as well as circularly polarized electroluminescence signal with g EL = −0.9 × 10 –3 /+1.0 × 10 –3 .