Li Gang, Li Nengquan, Cao Yibo, Shi Chao, Liu Xinyu, Zeng Ruoqi, Wu Meng, Li Qiuxia, Yang Chuluo, Yuan Aihua
School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, P. R. China.
College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, P. R. China.
Inorg Chem. 2022 Jul 11;61(27):10548-10556. doi: 10.1021/acs.inorgchem.2c01443. Epub 2022 Jun 28.
We have designed and synthesized a new family of neutral phosphorescent iridium(III) complexes (- featuring three differently charged (0, -1, and -2) ligands, in which biphenyl () is used as a dianionic (-2) ligand, 4,6-difluorophenylpyridine () or 1-phenylisoquinoline () is used as a monoanionic (-1) ligand, and 2,2'-bipyridyl (), 1,10-phenanthroline (), 1,2-bis(diphenylphosphanyl)benzene (), or 1,2-bis(diphenylphosphanyl)ethane () is used as a neutral (0) ligand. The X-ray structures confirm that three coordination carbon atoms of all complexes assume a facial geometry, which can be beneficial to the stability of the structure. More importantly, the emitting color of the complexes can be tuned from deep red/near-infrared (NIR) (680-710 nm) to blue-green (466-496 nm) with different monoanionic (-1) ligands and neutral (0) ligands. Interestingly, the complex shows a significant aggregation-induced phosphorescent emission effect, while with a similar structure shows an opposite aggregation-caused quenching effect, mainly due to slight differences in the neutral (0) ligand structure. Notably, all deep red/NIR-emitting complexes (-) exhibit a distinct charge transfer (CT) excited state from the dianionic (-2) ligand to the neutral (0) ligand according to density functional theory calculations, whereas the excited state of blue-green-emitting complexes (-) displays the CT from the dianionic (-2) ligand to the monoanionic (-1) ligand. Considering better stability and optical performance, the deep red-emitting complexes ( and ) with a simple structure are used as emitting layers of organic light-emitting diode devices and achieved good maximum external quantum efficiency (4.9 and 5.8%) peaking at 676 and 655 nm, respectively, with a very low turn-on voltage (2.5 V). This research provides a good strategy for the design of phosphorescent iridium complexes based on three differently charged (0, -1, and -2) ligands and their optoelectric applications.
我们设计并合成了一类新型的中性磷光铱（III）配合物，其具有三种不同电荷（0、-1和-2）的配体，其中联苯用作二价阴离子（-2）配体，4,6-二氟苯基吡啶或1-苯基异喹啉用作单价阴离子（-1）配体，2,2'-联吡啶、1,10-菲咯啉、1,2-双（二苯基膦基）苯或1,2-双（二苯基膦基）乙烷用作中性（0）配体。X射线结构证实，所有配合物的三个配位碳原子呈面式几何构型，这有利于结构的稳定性。更重要的是，通过使用不同的单价阴离子（-1）配体和中性（0）配体，配合物的发射颜色可以从深红色/近红外（NIR）（680-710 nm）调至蓝绿色（466-496 nm）。有趣的是，配合物显示出显著的聚集诱导磷光发射效应，而具有相似结构的配合物则表现出相反的聚集导致猝灭效应，这主要是由于中性（0）配体结构的细微差异。值得注意的是，根据密度泛函理论计算，所有深红色/近红外发射配合物均表现出从二价阴离子（-2）配体到中性（0）配体的明显电荷转移（CT）激发态，而蓝绿色发射配合物的激发态则显示出从二价阴离子（-2）配体到单价阴离子（-1）配体的CT。考虑到更好的稳定性和光学性能，结构简单的深红色发射配合物（和）被用作有机发光二极管器件的发光层，并分别在676和655 nm处实现了良好的最大外量子效率（4.9%和5.8%），开启电压非常低（2.5 V）。这项研究为基于三种不同电荷（0、-1和-2）配体的磷光铱配合物的设计及其光电应用提供了一个良好的策略。
