摘要/Abstract

基于螺[芴-9，9'-氧杂蒽]的位阻结构，在其芴端连接苯并噻唑构成共轭扩展的环金属配体，并成功合成了相应的均配、面式构型铱（III）配合物fac-Ir（SFXbtz）₃.配合物的最强发射峰位于587 nm，在635 nm处伴有肩峰发射；其在溶液中的磷光寿命为316 ns，光致发光量子产率达到64.7%.以fac-Ir（SFXbtz）₃为发射材料，在高掺杂浓度下分别制备了橙光电致发光器件及与蓝光材料FIrpic（双（4，6-二氟苯基吡啶-N，C²）吡啶甲酰合铱）组合的二元白光器件.以CBP（4，4'-二（9-咔唑）联苯）为主体材料的橙光器件最高电流效率和功率效率为10.8 cd·A^-1和8.4 lm·W^-1，最大亮度为7217 cd·m^-2.二元白光器件最高电流效率和功率效率为11.6 cd·A^-1和8.0 lm·W^-1，最大亮度为8763 cd·m^-2，在3~9 V操作电压下CIE1931色坐标稳定.结果表明：协同利用螺环芳烃的共轭结构和位阻结构优势，是获得低成本、本征光电性质良好及可高浓度掺杂的磷光铱（III）配合物的便捷方法.
关键词: 螺[芴-9,9'-氧杂蒽], 环金属铱(III)配合物, 共轭结构, 电致发光
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 Ir^III 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 Ir^III 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


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