Huang Tingting, Xu Yincai, Qu Yupei, Lu Xueying, Ye Kaiqi, Zhuang Xuming, Wang Yue
State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China.
Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, 117585, Singapore.
Adv Mater. 2025 Jun;37(24):e2503383. doi: 10.1002/adma.202503383. Epub 2025 Apr 3.
Developing diversified construction strategies for high-color-purity and efficient multiple resonance thermally activated delayed fluorescence (MR-TADF) materials is a major strategic demand to meet the requirements of ultra-high-definition organic light-emitting diode (OLED) displays, posing a significant challenge to the design and synthesis of emitters at the molecular level. Herein, a strategy is proposed for azepination-induced frontier molecular orbital (FMO) delocalization of MR emitters, that is, embedding azepine into the prototype molecule BNCz can effectively improve the π-conjugation degree and extend the FMO delocalization, thereby constructing a series of long-wavelength MR-TADF materials with narrowband emission. Through an intramolecular Scholl reaction, these target molecules with an azepine-embedded core are afforded by one-fold heptagonal cyclization of BNCz core and the phenyl ring attached to (aromatic amine-substituted) aryl precursor. They all exhibit efficient green emission around 520 nm and narrow full-widths at half-maximum (FWHMs) of ≤ 37 nm in toluene. OLEDs employing these emitters show excellent electroluminescence (EL) performances, among which m-PAz-BNCz-based OLED exhibits the optimal EL performances with a peak of 528 nm, a FWHM of 37 nm, Commission Internationale de L'Eclairage (CIE) coordinates of (0.26, 0.70), and a maximum external quantum efficiency (EQE) of 36.2%.
开发用于高色纯度和高效多重共振热激活延迟荧光（MR-TADF）材料的多样化构建策略是满足超高清有机发光二极管（OLED）显示器要求的一项重大战略需求，这对分子水平上发光体的设计与合成构成了重大挑战。在此，我们提出了一种用于MR发光体的氮杂环庚三烯化诱导前沿分子轨道（FMO）离域的策略，即把氮杂环庚三烯嵌入原型分子BNCz中可有效提高π共轭程度并扩展FMO离域，从而构建出一系列具有窄带发射的长波长MR-TADF材料。通过分子内肖尔反应，这些具有嵌入氮杂环庚三烯核心的目标分子由BNCz核心与连接到（芳胺取代的）芳基前体上的苯环进行单重七元环化反应得到。它们在甲苯中均表现出高效的绿色发射，发射峰位于520 nm左右，半高宽（FWHM）≤ 37 nm。采用这些发光体的OLED展现出优异的电致发光（EL）性能，其中基于m-PAz-BNCz的OLED表现出最佳的EL性能，其发射峰为528 nm，FWHM为37 nm，国际照明委员会（CIE）坐标为（0.26, 0.70），最大外量子效率（EQE）为36.2%。
