Green Phosphorescence and Electroluminescence of Sulfur Pentafluoride-Functionalized Cationic Iridium(III) Complexes

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• 作者：Nail M. Shavaleev ; Guohua Xie ; Shinto Varghese ; David B. Cordes ; Alexandra M. Z. Slawin ; Cristina Momblona ; Enrique Ort铆 ; Henk J. Bolink ; Ifor D. W. Samuel ; Eli Zysman-Colman
• 刊名：Inorganic Chemistry
• 出版年：2015
• 出版时间：June 15, 2015
• 年：2015
• 卷：54
• 期：12
• 页码：5907-5914
• 全文大小：548K
• ISSN：1520-510X

文摘

We report on four cationic iridium(III) complexes [Ir(C^N)₂(dtBubpy)](PF₆) that have sulfur pentafluoride-modified 1-phenylpyrazole and 2-phenylpyridine cyclometalating (C^N) ligands (dtBubpy = 4,4鈥?di-tert-butyl-2,2鈥?bipyridyl). Three of the complexes were characterized by single-crystal X-ray structure analysis. In cyclic voltammetry, the complexes undergo reversible oxidation of iridium(III) and irreversible reduction of the SF₅ group. They emit bright green phosphorescence in acetonitrile solution and in thin films at room temperature, with emission maxima in the range of 482鈥?19 nm and photoluminescence quantum yields of up to 79%. The electron-withdrawing sulfur pentafluoride group on the cyclometalating ligands increases the oxidation potential and the redox gap and blue-shifts the phosphorescence of the iridium complexes more so than the commonly employed fluoro and trifluoromethyl groups. The irreversible reduction of the SF₅ group may be a problem in organic electronics; for example, the complexes do not exhibit electroluminescence in light-emitting electrochemical cells (LEECs). Nevertheless, the complexes exhibit green to yellow-green electroluminescence in doped multilayer organic light-emitting diodes (OLEDs) with emission maxima ranging from 501 nm to 520 nm and with an external quantum efficiency (EQE) of up to 1.7% in solution-processed devices.