Ying Ao, Li Nengquan, Chen Xingyu, Xia Jianlong, Yang Chuluo, Gong Shaolong
College of Chemistry and Molecular Sciences, Hubei Key Laboratory on Organic and Polymeric Optoelectronic Materials, Wuhan University Wuhan 430072 China
Shenzhen Key Laboratory of New Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University Shenzhen 518060 China
Chem Sci. 2024 Nov 22;16(2):784-792. doi: 10.1039/d4sc04607b. eCollection 2025 Jan 2.
Carbene-metal-amide (CMA) complexes are appealing emitters for organic light-emitting diodes (OLEDs). However, little is known about silver(i)-CMA complexes, particularly electroluminescent ones. Here we report a series of Ag(i)-CMA complexes prepared using benzothiophene-fused carbazole derivatives as amide ligands. These complexes emit thermally activated delayed fluorescence (TADF), together with high photoluminescence quantum yields of up to 72% in thin films. By strengthening the π-donating ability of the amide ligands, ultrashort emission lifetimes of down to 144 ns in thin films and 11 ns in solution (with a radiative rate constant of ∼10 s) are realized, among the shortest lifetimes for TADF emitters. Key to this unique feature is the ultrafast spin-flip dynamics consisting of forward and reverse intersystem crossing rates of up to ∼10 s and ∼10 s, respectively, verified by the transient absorption spectroscopic study. The resulting solution-processed OLEDs based on the optimal complex afford record external quantum efficiencies of 16.2% at maximum and 13.4% at 1000 nits, representing the state-of-the-art performance for Ag(i) emitters. This work presents an effective approach for the development of short-lived TADF materials for high-efficiency OLEDs.
卡宾-金属-酰胺（CMA）配合物是有机发光二极管（OLED）中颇具吸引力的发光体。然而，人们对银（I）-CMA配合物，尤其是电致发光的配合物了解甚少。在此，我们报道了一系列使用苯并噻吩稠合咔唑衍生物作为酰胺配体制备的Ag（I）-CMA配合物。这些配合物发出热激活延迟荧光（TADF），在薄膜中的光致发光量子产率高达72%。通过增强酰胺配体的给π电子能力，实现了薄膜中低至144 ns、溶液中低至11 ns的超短发射寿命（辐射速率常数约为10 s），这在TADF发光体中是最短的寿命之一。这一独特特性的关键在于超快自旋翻转动力学，通过瞬态吸收光谱研究证实，其正向和反向系间窜越速率分别高达约10 s和约10 s。基于最佳配合物的溶液处理OLED在最大亮度下实现了创纪录的16.2%的外量子效率，在1000尼特亮度下为13.4%，代表了Ag（I）发光体的最高性能。这项工作为开发用于高效OLED的短寿命TADF材料提供了一种有效方法。
