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

• Published in: ACS applied materials & interfaces 2019-07, Vol.11 (29), p.26165-26173
• Main Authors: Wang, Yuxiang, Zhang, Yu, Hu, Wenrui, Quan, Yiwu, Li, Yunzhi, Cheng, Yixiang
• Format: Article
• Language: English
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.9b07005

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 (ΦPL) and delayed fluorescence lifetimes (τdelayed) 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.