Leung Ming-Yi, Tang Man-Chung, Cheng Shun-Cheung, Chen Ziyong, Lai Shiu-Lun, Tang Wai Kit, Chan Mei-Yee, Ko Chi-Chiu, Yam Vivian Wing-Wah
Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Pokfulam 999077, Hong Kong.
Hong Kong Quantum AI Lab Limited, 17 Science Park West Avenue, Pak Shek Kok 999077, Hong Kong.
J Am Chem Soc. 2024 Nov 13;146(45):30901-30912. doi: 10.1021/jacs.4c09207. Epub 2024 Oct 30.
A unique class of tridentate diaryltriazine ligand-containing gold(III) complexes with thermally activated delayed fluorescence (TADF) and/or thermally stimulated delayed phosphorescence (TSDP) properties has been designed and synthesized. With a simple structural modification on the coordination of carbazole moiety in the monodentate ligand, a large spectral shift of ∼160 nm (ca. 4900 cm) spanning from sky blue to red emissions has been demonstrated in solid-state thin films. Three-state or four-state models have been employed in fitting the emission lifetimes of the gold(III) complexes at various temperatures. The findings clearly indicate the presence of three emitting states, S, T, and T', suggesting the coexistence of TADF, phosphorescence, and TSDP. Notably, a minor structural change in the donor moiety between phenylcarbazolyl and diphenylaminoaryl has been demonstrated to turn on/off the TSDP, resulting in TADF-TSDP-phosphorescence or TADF-phosphorescence emitters. The TADF and/or TSDP properties have also been supported by temperature-dependent ultrafast transient absorption studies, with the direct observation of reverse intersystem crossing (RISC) and reverse internal conversion (RIC) and the determination of the activation parameters and excited state dynamics. Solution-processed and vacuum-deposited organic light-emitting devices (OLEDs) have been prepared, in which sky blue emitting devices based on exhibit an operational lifetime LT ∼ 5 times longer than the previously reported sky blue emitting analogue that shows only TSDP property. These results have provided valuable insights into the manipulation of the excited states via rational molecular design toward the realization of gold(III)-based TSDP and/or TADF materials with multiple radiative decay pathways that show enhanced radiative decay rate constants () for practical OLED applications.
已设计并合成了一类独特的含三齿二芳基三嗪配体的金（III）配合物，其具有热激活延迟荧光（TADF）和/或热激发延迟磷光（TSDP）特性。通过对单齿配体中咔唑部分的配位进行简单的结构修饰，在固态薄膜中已证明有跨越从天蓝到红光发射的约160 nm（约4900 cm）的大光谱位移。已采用三态或四态模型来拟合金（III）配合物在不同温度下的发射寿命。研究结果清楚地表明存在三种发射态，即S、T和T'，表明TADF、磷光和TSDP共存。值得注意的是，已证明供体部分在苯基咔唑基和二苯基氨基芳基之间的微小结构变化会开启/关闭TSDP，从而产生TADF-TSDP-磷光或TADF-磷光发射体。温度相关的超快瞬态吸收研究也支持了TADF和/或TSDP特性，直接观察到了反向系间窜越（RISC）和反向内转换（RIC），并确定了活化参数和激发态动力学。已制备了溶液处理和真空沉积的有机发光器件（OLED），其中基于 的天蓝发光器件的工作寿命LT比先前报道的仅显示TSDP特性的天蓝发光类似物长约5倍。这些结果为通过合理的分子设计来操纵激发态提供了有价值的见解，以实现具有多种辐射衰减途径的基于金（III）的TSDP和/或TADF材料，这些材料在实际OLED应用中显示出增强的辐射衰减速率常数（ ）。
