Wu Zheng-Guang, Yang Bing, Qiu Yu-Chen, Wang Yang, Dai Hong, Zheng You-Xuan, Wang Yi, Hu Lanping, Pan Yi
College of Chemistry and Chemical Engineering, Nantong University, Nantong, Jiangsu 226019, P. R. China.
Dalton Trans. 2021 Mar 21;50(11):3887-3893. doi: 10.1039/d0dt03981k. Epub 2021 Feb 26.
At present, cyclometalated iridium (Ir)(iii) complexes are the most promising emitters for OLEDs. Contrary to well-developed Ir(iii)-based red and green phosphorescent complexes, the efficient blue emitters are limited and the performances of blue OLEDs are still not satisfactory. Inspired by this, we designed two novel blue Ir(iii) complexes employing 2-(2,4-difluoropyridyl)pyridine (dfpypy) and 2,6-difluoro-3-(pyridin-2-yl)benzonitrile (FCN) as the main ligands, respectively, and phenyl(pyridin-2-yl)phosphinate (ppp) as the ancillary ligand. The rational design of the molecular structure makes the two complexes achieve blue emission and possess good electron mobility simultaneously. The devices based on the Ir(iii) phosphors exhibited good electroluminescence performances with low turn-on voltages, a peak current efficiency of 24.51 cd A, a maximum external quantum efficiency of 12.4%, a peak power efficiency of 21.99 lm W and low efficiency roll-off. These results provide an effective strategy for the future molecular design of blue Ir(iii) complexes with good electron transport property for OLEDs.
目前，环金属化铱（Ir）（iii）配合物是有机发光二极管（OLED）中最有前景的发光材料。与成熟的基于Ir（iii）的红色和绿色磷光配合物不同，高效蓝色发光材料有限，蓝色OLED的性能仍不尽人意。受此启发，我们分别设计了两种新型蓝色Ir（iii）配合物，以2-（2,4-二氟吡啶基）吡啶（dfpypy）和2,6-二氟-3-（吡啶-2-基）苯甲腈（FCN）作为主要配体，并以苯基（吡啶-2-基）次膦酸酯（ppp）作为辅助配体。分子结构的合理设计使这两种配合物实现了蓝色发光，同时具有良好的电子迁移率。基于Ir（iii）磷光体的器件表现出良好的电致发光性能，开启电压低，峰值电流效率为24.51 cd/A，最大外量子效率为12.4%，峰值功率效率为21.99 lm/W，且效率滚降低。这些结果为未来设计具有良好电子传输性能的蓝色Ir（iii）配合物用于OLED提供了一种有效策略。
