Sky-blue phosphorescent iridium(III) complexes with two substituted 2-phenylpyridine derivatives and one picolinic acid for organic light-emitting diodes

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• 作者：Seong-Jae Yun^a ; Hoe-Joo Seo^b ; Myungkwan Song^a ; Sung-Ho Jin^a ; Sung Kwon Kang^c ; Young-Inn Kim^a ; ^{yikim@pusan.ac.kr}
• 关键词：Phosphorescent iridium(III) complex ; Sky-blue phosphorescent emitting materials ; Organic light-emitting diodes (OLEDs)
• 刊名：Journal of Organometallic Chemistry
• 出版年：2013
• 出版时间：15 January, 2013
• 年：2013
• 卷：724
• 期：Complete
• 页码：244-250
• 全文大小：598 K

文摘

Two sky-blue phosphorescent heteroleptic cyclometalated iridium(III) complexes, bis(2-(2¡ä,4¡ä-difluoro-3¡ä-trifluoromethylphenyl)-4-methylpyridinato-N,C^2¡ä)iridium(picolinate) [(dfpmpyCF₃)₂Ir(pic)] (1) and bis(2-(2¡ä,4¡ä-difluoro-3¡ä-hexylcarbazolephenyl)-4-methylpyridinato-N,C^2¡ä)iridium(picolinate) [(dfpmpyh-Cz)₂Ir(pic)] (2), were synthesized and characterized. Energy transfer from the carbazol moiety to the iridium core in compound 2 resulted in higher quantum efficiency than with compound 1. The electronegative effect of the -CF₃ group on the phenyl ring in the phenylpyridine main ligand resulted in a hypsochromic shift of the emitting spectra in compound 1. In contrast, the sky-blue emission without a red shift in compound 2 indicated a negligible inductive effect of the long chain hexylcarbazole unit on the electronic state of the phenyl ring. The single crystal X-ray structural analysis showed that compound 1 adopts a distorted octahedral geometry around the iridium metal exhibiting cis-C,C¡ä and trans-N,N¡ä chelate disposition. An electroluminescent devices using the iridium complexes as a dopant in the emitting layer has been fabricated. The best device performance based on compound 1 demonstrated a maximum luminance (L), external quantum efficiency (EQE), luminance efficiency (LE) and power efficiency (PE) of 5750?cd/m², 7.53 % , 16.86?cd/A and 5.88?lm/W, respectively with Commission Internationale de L'Eclairage (CIE) coordinates of (0.17,0.40).