Through‐Space Charge‐Transfer Polynorbornenes with Fixed and Controllable Spatial Alignment of Donor and Acceptor for High‐Efficiency Blue Thermally Activated Delayed Fluorescence

• Published in: Angewandte Chemie International Edition 2020-11, Vol.59 (45), p.20174-20182
• Main Authors: Li, Qiang, Hu, Jun, Lv, Jianhong, Wang, Xingdong, Shao, Shiyang, Wang, Lixiang, Jing, Xiabin, Wang, Fosong
• Format: Article
• Language: English
• Subjects: Alignment; blue emission; Charge transfer; Dendritic structure; Efficiency; Fluorescence; Photoluminescence; Photons; Polymers; Polynorbornene; Quantum efficiency; Space charge; spatial alignment; Stacking; thermally activated delayed fluorescence; through-space charge transfer
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202008912

Through‐space charge transfer polynorbornenes with fixed and controllable spatial alignment of donor and acceptor in edge‐to‐face/face‐to‐face stacking patterns are developed for achieving high‐efficiency blue thermally activated delayed fluorescence (TADF). The alignment is realized by using the cis, exo‐configuration of norbornene to confine donor and acceptor in close proximity, and utilizing orthogonal and dendritic structures of donors to provide either perpendicular or parallel stacking motif relative to acceptors. Compared to edge‐to‐face counterparts, polynorbornenes with face‐to‐face aligned donor and acceptor exhibit much larger oscillator strength and higher photoluminescence quantum yield. The resulting polymers exhibit deep blue (422 nm) to sky blue (482 nm) emission and TADF effect with reverse intersystem crossing rates of 0.4–5.9×106 s−1, giving the maximum external quantum efficiency of 18.8 % for non‐doped blue organic light‐emitting diodes by solution process. Through‐space charge transfer polynorbornenes with fixed and controllable spatial alignment of donor and acceptor in edge‐to‐face/face‐to‐face stacking patterns are demonstrated to exhibit blue thermally activated delayed fluorescence (TADF) together with maximum external quantum efficiency of 18.8 % for non‐doped, solution‐processed OLEDs.