B‒N covalent bond-involved π-extension of multiple resonance emitters enables high-performance narrowband electroluminescence  

作　　者：Xingyu Huang Jiahui Liu Yulin Xu Guohao Chen Manli Huang Mingxin Yu Xialei Lv Xiaojun Yin Yang Zou Jingsheng Miao Xiaosong Cao Chuluo Yang 

机构地区：[1]Shenzhen Key Laboratory of New Information Display and Storage Materials,College of Materials Science and Engineering,Shenzhen University,Shenzhen 518060,China [2]College of Physics and Optoelectronic Engineering,Shenzhen University,Shenzhen 518060,China

出　　处：《National Science Review》2024年第6期236-246,共11页国家科学评论（英文版）

基　　金：supported by the National Natural Science Foundation of China(52130308,22375130 and 52373192);the Shenzhen Technology and Innovation Commission(JCYJ20230808105603008,JCYJ20220818095816036 and ZDSYS20210623091813040).

摘　　要：Multi-boron-embedded multiple resonance thermally activated delayed fluorescence (MR-TADF) emittersshow promise for achieving both high color-purity emission and high exciton utilization efficiency.However, their development is often impeded by a limited synthetic scope and excessive molecular weights,which challenge material acquisition and organic light-emitting diode (OLED) fabrication by vacuumdeposition. Herein, we put forward a B–N covalent bond-involved π-extension strategy viapost-functionalization of MR frameworks, leading to the generation of high-order B/N-based motifs. Thestructurally and electronically extended π-system not only enhances molecular rigidity to narrow emissionlinewidth but also promotes reverse intersystem crossing to mitigate efficiency roll-off. As illustratedexamples, ultra-narrowband sky-blue emitters (full-width at half-maximum as small as 8 nm in n-hexane)have been developed with multi-dimensional improvement in photophysical properties compared to theirprecursor emitters, which enables narrowband OLEDs with external quantum efficiencies (EQE_(max)) of upto 42.6%, in company with alleviated efficiency decline at high brightness, representing the best efficiencyreported for single-host OLEDs. The success of these emitters highlights the effectiveness of our moleculardesign strategy for advanced MR-TADF emitters and confirms their extensive potential in high-performanceoptoelectronic devices.

关 键 词：narrowband electroluminescence thermally activated delayed fluorescence(TADF) multiple resonance emitters ultra-high external quantum efficiency 

分 类 号：TM912[电气工程—电力电子与电力传动]