Wang Yang, Wang Shumeng, Ding Junqiao, Wang Lixiang
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China.
Department of Materials Science and Engineering and The Shenzhen Key Laboratory for Printed Organic Electronics, Southern University of Science and Technology of China (SUSTech), Shenzhen 518055, P. R. China.
ACS Omega. 2018 Nov 12;3(11):15308-15314. doi: 10.1021/acsomega.8b02579. eCollection 2018 Nov 30.
A dendritic multinuclear Ir complex, namely Cz-3IrB-IrG, has been designed and synthesized by introducing the second-generation oligocarbazole dendrons into its periphery. Because of the characteristic encapsulation, the intermolecular interactions could be effectively alleviated to prevent the unwanted triplet-triplet annihilation stemmed from the outer blue Ir complexes. Compared with 3IrB-IrG in the absence of dendrons, the film photoluminescence quantum yield of Cz-3IrB-IrG is greatly increased from 0.46 to 0.82 together with a small blue-shifted emission from 524 to 520 nm. On the basis of Cz-3IrB-IrG as the emitting layer alone, the nondoped device realizes a promising luminous efficiency of 40.9 cd/A (12.0%), much higher than that of 3IrB-IrG (32.6 cd/A, 9.7%). The obtained improvement clearly indicates that further dendronization toward multinuclear Ir complex will provide an alternative strategy to construct highly efficient phosphors used for nondoped phosphorescent organic light-emitting diodes.
通过将第二代低聚咔唑树枝状分子引入其外围，设计并合成了一种树枝状多核铱配合物，即Cz-3IrB-IrG。由于其独特的封装作用，分子间相互作用可得到有效缓解，从而防止由外部蓝色铱配合物引发的不必要的三重态-三重态湮灭。与不存在树枝状分子的3IrB-IrG相比，Cz-3IrB-IrG的薄膜光致发光量子产率从0.46大幅提高到0.82，同时发射光谱有小的蓝移，从524 nm变为520 nm。仅以Cz-3IrB-IrG作为发光层，非掺杂器件实现了40.9 cd/A（12.0%）的有前景的发光效率，远高于3IrB-IrG（32.6 cd/A，9.7%）。所获得的改进清楚地表明，对多核铱配合物进一步进行树枝状化将为构建用于非掺杂磷光有机发光二极管的高效磷光体提供一种替代策略。
