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Updated: Aug 12, 2025

Magnetic Tweezers for the Measurement of Twist and Torque
Published on: May 19, 2014
Medium-Ring Strategy Enables Multiple Resonance Emitters with Twisted Geometry and Fast Spin-Flip to Suppress
Bowen Lei1, Zhenmei Huang1, Songtao Li1
1Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu, 610064, P. R. China.
Abstract:
Suppressing aggregation-caused quenching (ACQ) effect and reducing device efficiency roll-off are both crucial yet challenging for multi-resonance (MR) emitters. Herein, we put forward a medium-ring strategy to design efficient MR emitters that feature heptagonal tribenzo[b,d,f]azepine (TBA) donors. The highly twisted conformation enlarges the intermolecular distances between the MR-emitting cores, and thus suppresses ACQ effect. Meanwhile, the introduction of heptagonal donors enhances spin-orbital coupling, so as to accelerate reverse intersystem crossing (RISC) process. This medium-ring strategy gives rise to the first example of blue MR emitter that simultaneously possesses radiative decay rate as fast as 108 s-1 and RISC rate as fast as 106 s-1 . Accordingly, DTBA-B2N3 enables to assemble high-performance blue organic light-emitting diodes (OLEDs) with maximum external quantum efficiency (EQEmax ) of 30.9 % and alleviated efficiency roll-off (EQE1000 : 20.5 %).
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