Acta Chimica Sinica ›› 2020, Vol. 78 ›› Issue (1): 56-62.DOI: 10.6023/A19110406 Previous Articles     Next Articles



任保轶a, 依建成a, 钟道昆a, 赵玉志a, 郭闰达c, 盛永刚a,b, 孙亚光a, 解令海b, 黄维b   

  1. a 沈阳化工大学 应用化学学院 辽宁省无机分子基化学重点实验室 沈阳 110142;
    b 南京邮电大学 江苏省有机电子与信息显示重点实验室-省部共建国家重点实验室培育基地 南京 210023;
    c 华中科技大学 武汉光电国家研究中心 武汉 430074
  • 投稿日期:2019-11-15 发布日期:2019-12-20
  • 通讯作者: 郭闰达, 孙亚光;
  • 基金资助:

Conjugated Regulation of Phosphorescent Iridium (III) Complex Constructed from Spiro Ligand and Its Electroluminescent Performances

Ren Bao-Yia, Yi Jian-Chenga, Zhong Dao-Kuna, Zhao Yu-Zhia, Guo Run-Dac, Sheng Yong-Ganga,b, Sun Ya-Guanga, Xie Ling-Haib, Huang Weib   

  1. a Key Laboratory of Inorganic Molecule-Based Chemistry of Liaoning Province, College of Applied Chemistry, Shenyang University of Chemical Technology, Shenyang 110142;
    b Key Laboratory for Organic Electronics and Information Displays, Institute of Advanced Materials(IAM), Nanjing University of Posts & Telecommunications, Nanjing 210023;
    c Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074
  • Received:2019-11-15 Published:2019-12-20
  • Supported by:
    Project supported by the Supporting Project for Innovative Talents of Higher Education Institutions in Liaoning Province (LR2018018), the Natural Science Foundation of Liaoning Province (No. 20180550539), the Science and Technology project of Shenyang (No. 18-013-0-26), and the Open Research Fund of Key Laboratory for Organic Electronics and Information Displays.

It is an important pathway in the field of phosphorescent organic light-emitting diodes (PhOLED) that endowing iridium (III) emitters with the features of low-cost, decent photoelectric properties, and high doping-concentration application by harmonizing electronic and steric effects of corresponding ligands. Based on our previous research that introducing spiro ligand into IrIII complexes to protect emitting-center and to suppress concentration quenching, herein, for pushing the emission to orange region, we extend the conjugated structure of spiro[fluorene-9,9'-xanthene] (SFX) by connected benzo[d]-thiazole-2-yl on the fluorene moiety of SFX via Suzuki-Miyaura coupling, acting as a new spiro ligand. A homoleptic IrIII complex, fac-Ir(SFXbtz)3, was synthesized successfully, and the structure and the photophysical and electrochemical properties were studied by nuclear magnetic resonance, single crystal X-ray diffraction, absorption and emission measurements, as well as cyclic voltammetry. The crystallographic data revealed an enlarged Ir…Ir distance and weakly intermolecular π-π interactions between the spiro ligands. The emission spectrum of fac-Ir(SFXbtz)3 showed a maximum peak at 587 nm and a shoulder peak at 635 nm with a photoluminescence (PL) quantum yield (QY) of 64.7% (relative to tris[2-phenylpyridinato-C2,N]iridium(III), PLQY=40%). The highest occupied molecular orbital level was determined to be -5.28 eV according to the onset oxidation potential (0.48 V). In view of the orange light-emitting and the high PLQY of fac-Ir(SFXbtz)3, the monochromatic and two-element white PhOLED were fabricated to investigate its electroluminescence (EL) performance in high doping concentrations, ω=12% for monochromatic device and ω=15% for two-element white device, respectively. The EL spectrum of the monochromatic PhOLED (device D1) using common 4,4'-bis(N-carbazolyl)-1,1'-biphenyl as host exhibits two emission peaks, a maximum emission peak at 581 nm and shoulder emission peak at 631 nm, corresponding to its PL spectrum. The device D1 shows a peak performance of 10.8 cd·A-1 and 8.4 lm·W-1, maximum brightness of 7217 cd·m-2, respectively. The two-element white PhOLED selecting bis[2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato)iridium(III) as complementary blue-light component, possesses a peak performance of 11.6 cd·A-1 and 8.0 lm·W-1, maximum brightness of 8763 cd·m-2, and stabilized CIE 1931 (0.34~0.37, 0.36~0.38) under operated voltages of 3~9 V, respectively. These results indicate that the fac-Ir(SFXbtz)3 is a potential phosphor for efficient orange PhOLED, possessing the advantages of low-cost, suitable doping in high concentration, and stabilized color coordinates.

Key words: spiro[fluorene-9,9'-xanthene], cyclometalated iridium (III) complex, conjugated structure, electroluminescence