You Caifa, Wang Xue-Qi, Zhou Xiuwen, Yuan Yi, Liao Liang-Sheng, Liao Yu-Chan, Chou Pi-Tai, Chi Yun
Department of Materials Sciences and Engineering, Department of Chemistry, Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Kowloon Tong, Kowloon 999077, Hong Kong SAR, China.
Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University, Suzhou, Jiangsu 215123, China.
ACS Appl Mater Interfaces. 2021 Dec 15;13(49):59023-59034. doi: 10.1021/acsami.1c17308. Epub 2021 Dec 5.
In this report, we synthesized two series of deep-blue-emitting homoleptic iridium(III) phosphors bearing 1,2,4-triazol-3-ylidene and 5-(trifluoromethyl)-1,2,4-triazol-3-ylidene cyclometalate. Compared with reported synthetic routes using AgO as the promoter, herein, we adopted a different strategy to furnish these complexes in high yields. Also, the meridional to facial isomerization was executed in the presence of trifluoroacetic acid. These phosphors were examined using NMR spectroscopies, single-crystal X-ray diffraction studies, and photophysical methods. The results revealed that electron-withdrawing trifluoromethyl substitution on the N-heterocyclic carbene fragment only gave a minor variation of photoluminescence peak wavelengths and a decrease in radiative lifetime but notable reduction in thermal stabilities. The parent 1,2,4-triazol-3-ylidene complexes have been demonstrated to be suitable for use as deep-blue phosphors, with structured emission with the peak max. located at ∼420 nm and with photoluminescence quantum yields in a range of 34.8-42.5% in degassed THF solution at RT. Fabrication of both the phosphorescent organic light-emitting diodes (OLEDs) and phosphor-sensitized OLEDs (or hyperphosphorescence) was successfully conducted, from which the OLED device based on showed a max. external quantum efficiency (EQE) of 10% with CIE coordinates of 0.15, 0.06, while the corresponding hyperphosphorescent OLED using as a sensitizer and -DABNA as a terminal emitter afforded a significantly improved max. EQE of 19.7%, EL λ of 468 nm, and FWHM of 31 nm with CIE coordinates of 0.12, 0.13.
在本报告中，我们合成了两个系列的深蓝色发射同配铱(III)磷光体，它们带有1,2,4-三唑-3-亚基和5-(三氟甲基)-1,2,4-三唑-3-亚基环金属酸盐。与报道的使用AgO作为促进剂的合成路线相比，在此我们采用了不同的策略以高收率制备这些配合物。此外，在三氟乙酸存在下进行了经式到面式的异构化。使用核磁共振光谱、单晶X射线衍射研究和光物理方法对这些磷光体进行了研究。结果表明，在N-杂环卡宾片段上吸电子的三氟甲基取代仅使光致发光峰值波长有微小变化，辐射寿命降低，但热稳定性显著降低。已证明母体1,2,4-三唑-3-亚基配合物适合用作深蓝色磷光体，其发射结构的最大峰值位于~420 nm，在室温下脱气的四氢呋喃溶液中的光致发光量子产率在34.8-42.5%范围内。成功制备了磷光有机发光二极管(OLED)和磷光体敏化OLED(或超磷光)，基于该[此处原文缺失具体配合物名称]的OLED器件显示出最大外量子效率(EQE)为10%，CIE坐标为0.15, 0.06，而使用[此处原文缺失具体配合物名称]作为敏化剂和[此处原文缺失具体配合物名称]作为末端发射体的相应超磷光OLED的最大EQE显著提高至19.7%，EL λ为468 nm, FWHM为31 nm，CIE坐标为0.12, 0.13。
