Yan Jie, Xue Qin, Yang Hui, Yiu Shek-Man, Zhang Ye-Xin, Xie Guohua, Chi Yun
Department of Materials Science and Engineering, Department of Chemistry, Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Kowloon 999077, Hong Kong SAR, China.
Department of Physical Science and Technology, Central China Normal University, Wuhan 430079, China.
Inorg Chem. 2022 Jun 13;61(23):8797-8805. doi: 10.1021/acs.inorgchem.2c00750. Epub 2022 Jun 2.
Six homoleptic Ir(III) complexes bearing imidazo[4,5-]pyrazin-2-ylidene chelates were successfully designed and synthesized. Narrowband blue emission (λ = 466-485 nm) and broadened green emission (λ = 518-532 nm) in degassed toluene solution with high photoluminescent quantum yields in the range of 75-81 and 45-48% were observed for , , and as well as , , and , respectively. In addition, the -butylphenyl cyclometalate is more electron donating than -phenyl cyclometalate and, hence, all -butylphenyl-substituted derivatives, that is, and and and , give more red-shifted emission in comparison to that of and . Moreover, solution-processed OLED with (20 wt %) as the dopant gave electrophosphorescence at 474 nm with maximum external quantum efficiency (max. EQE) of 5.1%, while hyper-OLED with assistant sensitizer (10 wt %) and the multi-resonance thermally activated delayed fluorescence emitter (0.5 wt %) afforded narrowband emission centered at 485 nm and max. EQE up to 17.4%, confirming the high potential of this class of Ir(III) metal phosphors.
成功设计并合成了六种带有咪唑并[4,5 - ]吡嗪 - 2 - 亚基螯合物的均配型Ir(III)配合物。在脱气甲苯溶液中，观察到 、 、 以及 、 、 分别呈现窄带蓝光发射（λ = 466 - 485 nm）和宽带绿光发射（λ = 518 - 532 nm），其光致发光量子产率较高，分别在75 - 81%和45 - 48%范围内。此外，叔丁基苯基环金属配体比苯基环金属配体的给电子能力更强，因此，所有叔丁基苯基取代的衍生物，即 和 以及 和 ，与 和 相比，发射峰发生了更大的红移。而且，以 （20 wt%）作为掺杂剂的溶液处理OLED在474 nm处产生电磷光，最大外量子效率（max. EQE）为5.1%，而含有辅助敏化剂 （10 wt%）和多共振热激活延迟荧光发射体 （0.5 wt%）的超OLED产生了以485 nm为中心的窄带发射，最大外量子效率高达17.4%，证实了这类Ir(III)金属磷光体具有很高的潜力。
