Acta Phys. -Chim. Sin. ›› 2016, Vol. 32 ›› Issue (6): 1534-1542.doi: 10.3866/PKU.WHXB201603232

• ARTICLE • Previous Articles     Next Articles

One-Step Synthesis of Spirobi[fluorene] and Spiro[fluorene-9,9′-xanthene] Derivatives and Their Applications in Organic Light-Emitting Devices: Performance Enhancement and Related Optical Phenomena

Yu-Qiao GUAN1,#,Juan SONG1,#,Wei SUN1,Qin ZHANG1,Chao TANG2,Xue LI3,Xiao-Miao FENG1,Yan QIAN1,You-Tian TAO2,Shu-Fen CHEN1,*(),Lian-Hui WANG1,Wei HUANG2,*()   

  1. 1 Key Laboratory for Organic Electronics and Information Displays and Institute of Advanced Materials, and Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing University of Posts and Telecommunications, Nanjing 210023, P. R. China
    2 Key Laboratory of Flexible Electronics and Institute of Advanced Materials, National Synergistic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing 211816, P. R. China
    3 Mechanical Engineering Institute, Nanjing Institute of Technology, Nanjing 211167, P. R. China
  • Received:2016-01-05 Published:2016-06-03
  • Contact: Shu-Fen CHEN,Wei HUANG E-mail:iamsfchen@njupt.edu.cn;wei-huang@njtech.edu.cn
  • Supported by:
    The project was supported by the National Key Basic Research Program of China(9732015CB932202, 2012CB933301);National Natural Science Foundation of China(61274065, 51173081, 61136003, BZ2010043, 51372119, 51172110, 21304047, 21373114, 21003076);Innovation Team of the Ministry of Education of China(IRT1148);Ministry of Education Humanities and Social Science Research Projects, China(13YJCZH091);Natural Science Foundation of Jiangsu Province, China(BK20141424);Priority Academic Program Development of Jiangsu Provincial Higher Education Institutions, China(YX030001);Ordinary University Graduate Student Practical Innovation Projects of Jiangsu Province, China(SJLX15_0390);Pandeng Project of Nanjing University of Posts and Telecommunications, China(NY214085);Open Foundation from Jilin University, China(IOSKL2015KF32)

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Abstract:

Employing fluorene as substrate, we synthesized a new spirobifluorene derivative, 2′-(9-phenylfluoren- 9-yl)-9,9′-spirobi[fluorene] (PF-SBF), through a one-step palladium-catalyzed cross-coupling reaction. Utilizing PF-SBF as an emitter and as a host of the blue phosphor bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2- carboxypyri-dyl))iridium(III) (FIrpic) in organic light-emitting devices (OLEDs), we observed a red light band different from the intrinsic blue emission of PF-SBF and FIrpic. This was attributed to the intermolecular aggregation of PF-SBF and to exciplexes generated at the interfaces of the emitting layer and the electron transport layer. The exciplex emission was then restrained through a suitable selection of hole and electron transport layer. Employing PF-SBF with di-[4-(N,N-ditolyl-amino)-phenyl]cyclohexane (TAPC) as a cohost, we obtained high-performance blue and green emissions from FIrpic and tris(2-phenylpyridine)iridium(III) (Ir(ppy)3). The maximum current efficiencies and luminances of the blue and green OLEDs were as high as 16.7 and 50.5 cd·A-1 and 7857 (at 11 V) and 23390 cd·m-2 (at 8 V), respectively. As an alternative to PF-SBF, we also synthesized a new xanthene derivative, 2-(9-phenyl-fluoren-9-yl)spiro[fluorene-9,9′-xanthene] (PF-SFX), with a large triplet energy level of 2.8 eV. Using PF-SFX similarly as a host of FIrpic, the current efficiency and luminance were significantly improved to 22.6 cd·A-1 and 6421 cd·m-2 (at 10 V). These results demonstrate the potential of PF-SBF and PF-SFX as new building blocks for high-efficiency green/blue phosphorescent host materials.

Key words: Palladium catalysis, One-step method, Exciplex, Cohost, Blue organic light-emitting diode