Multiple‐Resonance‐Induced Thermally Activated Delayed Fluorescence Materials Based on Indolo[3,2,1‐jk]carbazole with an Efficient Narrowband Pure‐Green Electroluminescence

Herein, we report two multiple‐resonance thermally activated delayed fluorescence emitters (VTCzBN and TCz‐VTCzBN) based on indolo[3,2,1‐jk]carbazole unit and boron‐nitrogen skeletons, whose emissions peaking at 496 and 521 nm with full width at half maximum of 34 and 29 nm, respectively. Meanwhile,...

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Published in:Angewandte Chemie International Edition 2022-10, Vol.61 (41), p.e202209984-n/a
Main Authors: Luo, Xu‐Feng, Song, Shi‐Quan, Ni, Hua‐Xiu, Ma, Huili, Yang, Dezhi, Ma, Dongge, Zheng, You‐Xuan, Zuo, Jing‐Lin
Format: Article
Language:English
Subjects:
Fast Reverse Intersystem Crossing
Multiple Resonance
Organic Light-Emitting Diode
Pure Green
Thermally Activated Delayed Fluorescence
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Summary:Herein, we report two multiple‐resonance thermally activated delayed fluorescence emitters (VTCzBN and TCz‐VTCzBN) based on indolo[3,2,1‐jk]carbazole unit and boron‐nitrogen skeletons, whose emissions peaking at 496 and 521 nm with full width at half maximum of 34 and 29 nm, respectively. Meanwhile, fast rate constants of reverse intersystem crossing of above 106 s−1 are obtained due to small singlet‐triplet energy gaps and large spin‐orbital coupling values. Notably, planar molecular structures along the transition dipole moment direction endow them with high horizontal emitting dipole ratios of up to 94 %. Consequently, the corresponding organic light‐emitting diodes (OLEDs) show the maximum external quantum efficiencies of 31.7 % and 32.2 %, respectively. Particularly, OLED with TCz‐VTCzBN display ultra‐pure green emission with Commission Internationale de l′Eclairage coordinates of (0.22, 0.71), consistent with the green display standard of the National Television System Committee. Combining the multiple‐resonance ability of the indolo[3,2,1‐jk]carbazole unit with boron‐nitrogen skeletons has led to compounds that show efficient green emission (CIE: 0.21, 0.71) and efficient reverse intersystem crossing (RISC). OLEDs incorporating these multiple‐resonance‐induced thermally activated delayed fluorescence materials show a pure narrowband green emission (CIE: 0.22, 0.71) and a high external quantum efficiency (EQE) of 32.2 %
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.202209984