【作者】 孙静；

【导师】 许并社；

【作者基本信息】 太原理工大学 ， 材料科学与工程， 2016， 博士

【摘要】 白光有机电致发光器件由于轻薄、节能、柔性和高对比度等优势,在固态照明,液晶背光源及平板显示方面显示了极大的潜力。磷光铱(Ⅲ)配合物由于其自旋轨道耦合作用,可以同时捕获单线态和三线态激子,在理论上实现内量子效率100%,但是存在较强的三线态湮灭现象,主要通过物理掺杂的方法制备白光有机电致发光器件。由于不同材料的性能不同,会产生相分离现象,影响了器件的使用寿命,不利于制备大面积柔性器件,同时其器件制备工艺复杂,多层结构的界面问题较多,在蒸镀过程中材料浪费比较严重,提高了器件的制备成本。而聚合物掺杂制备的白光聚合物有机电致发光器件同样存在相分离现象,影响了器件的电致发光性能。因此,单一白光聚合物有机电致发光材料应运而生,通过化学键将磷光铱(Ⅲ)配合物接入主体聚合物材料中,有效地避免了相分离现象,简化了器件制备工艺,同时可以制备大面积柔性器件,在白光照明方面具有较大的应用价值。基于此,我们主要开展了以下研究工作:1.将磷光铱(Ⅲ)配合物引入到具有较大空间位阻的超支化结构,作为其支化点,利用超支化结构的骨架将铱(Ⅲ)配合物有效分离,抑制其三线态湮灭。在此基础上,设计并合成了均配带溴的三[1-(4-溴苯基)异喹啉]合铱(Ⅲ)[Ir(piqBr)3],将其作为红光核心的反应单体,合成了一系列以Ir(piq)3为红光核心,蓝色9,9-二辛基芴为超支化骨架的白光超支化共轭聚合物,该类聚合物具有较高的荧光量子效率(57%~77%)。其中,当均配红光核心Ir(piq)3的含量为0.1 mol%时,白光超支化共轭聚合物PF-Ir(piq)3100具有最好的色坐标(0.30,0.23),接近于纯白光(0.33,0.33),其最大亮度为824cd/m2,最大电流效率为1.97cd/a。2.均配ir(piqbr)3的合成产率较低,增大了材料合成的成本,为此设计并合成了具有较高合成产率的异配含溴的二[1-(4-溴苯基)异喹啉][3-(2-吡啶)-5-(4-溴苯基)-1,2,4-三唑]合铱(Ⅲ)[ir(piqbr)2(pytzphbr)]反应单体。将ir(piq)2(pytzph)作为红光核心,聚9,9-二辛基芴作为蓝色荧光骨架,制备了基于互补色的白光超支化共轭聚合物。当红光核心ir(piq)2(pytzph)的含量为0.1mol%时,白光超支化共轭聚合物pf-ir(piq)2(pytzph)100具有最好的色坐标(0.25,0.27),最大亮度为2468cd/m2,最大电流效率为1.73cd/a,说明不同的红光铱(Ⅲ)配合物可以作为超支化结构的核心,用于制备白光超支化共轭聚合物。同时合成了通过ir(piq)2(pytzph)主配体嵌入聚芴主链的直链型聚合物linearpf-ir(piq)2(pytzph)m和将ir(piq)2(pytzph)作为封端基团引入到聚芴主链的直链型聚合物endcappedpf-ir(piq)2(pytzph)m。3.互补色白光超支化共轭聚合物的电致发光光谱在520~580nm范围内缺少发光峰,影响了电致发光光谱的饱和度。为此,在互补色白光的基础上,引入一种位于520~580nm处的发射单元,能够极大地提高电致发光光谱的饱和度。2,1,3-苯并噻唑-9,9-二辛基芴(pfbt)是一种性能较好的绿光发射材料。将其引入到白光超支化共轭聚合物,合成了一系列以ir(piq)3作为红光核心,绿色pfbt和蓝色聚9,9-二辛基芴作为骨架的三基色白光超支化共轭聚合物pf-btm-ir(piq)3n。该类材料具有良好的热稳定性能,光物理性能,电化学性能和成膜性。当bt含量为0.25mol%,ir(piq)3的含量为0.025mol%时,超支化共轭聚合物pf-bt250-ir(piq)325的电致发光光谱具有较高的色饱和度,其色坐标为(0.32,0.35),其最大亮度为3267cd/m2,最大电流效率为1.60cd/a。4.以pfbt作为绿光单元的白光超支化共轭聚合物得到了饱和的电致发光光谱,但是其电流效率较低。为了进一步提高其电致发光性能,设计并合成了一种绿色磷光铱(Ⅲ)配合物,异配的二[2-(4-溴苯基)吡啶][3-(2-吡啶)-5-(4-溴苯基)-1,2,4-三唑]合铱(Ⅲ)[Ir(ppyBr)2(pytzphBr)]。以Ir(ppy)2(pytzph)为绿光核心,Ir(piq)2(pytzph)为红光核心,聚9,9-二辛基芴为蓝色骨架合成了一系列三基色白光超支化共轭聚合物PF-Ir(ppy)2(pytzph)m-Ir(piq)2(pytzph)n。聚合物中,从Ir(ppy)2(pytzph)到Ir(piq)2(pytzph)的能量传递借助于核心之间的聚芴得以实现。当绿光Ir(ppy)2(pytzph)含量为0.25mol%,红光Ir(piq)2(pytzph)含量为0.05 mol%时,PF-Ir(ppy)2(pytzph)25-Ir(piq)2(pytzph)5的色坐标为(0.31,0.34),显色指数达到92,最大电流效率为7.81 cd/A,最大亮度为6030 cd/m2。绿色磷光铱(Ⅲ)配合物的引入,极大地提高了器件的电致发光性能。综上所述,本文合成了一系列以磷光铱(Ⅲ)配合物为核心基于互补色和三基色的白光超支化共轭聚合物。该类聚合物具有较大的空间位阻,能够有效地抑制磷光基团的三线态湮灭,提高白光器件的电致发光性能,同时磷光配合物直接嵌入到超支化结构的主链,有效地提高了能量传递效率。含有绿色磷光铱(Ⅲ)配合物的三基色白光超支化共轭聚合物具有最好的电致发光性能。白光超支化共轭聚合物作为一种单一分子的白光有机电致发光材料具有较大的实际应用价值,是一种值得期待的有机电致发光材料。更多还原

【Abstract】 White organic light emitting devices(WOLED) have shown great potential applications in the solid state lighting sources, back-lighting for LCD as well as large-area flat-panel displays due to their unique advantages of light-weight, low-power, flexible displays, high contrast and so on. Owing to the spin-orbit coupling effect, iridium(Ⅲ) complexes could capture both singlet and triplet excitons, and theoretically internal quantum efficiency reaches 100 %. However, iridium(Ⅲ) complexes exist serious triplet-triplet annihilation which must be blended in the host materials to fabricate WOLED. Because of the different properties of various components, blended systems exist serious phase separation which will reduce the electroluminescent(EL) performance and be bad for preparing large-area flexible WOLED. At the same time, the fabrication process of devices is complicated and more interfacial problems emerge. In the evaporation process, more complexes are wasted that improves the cost of WOLED. White polymer light emitting devices(WPLED) prepared by blended polymer system have the same problem of phase separation that influences the EL performace. Therefore, single white light emitting polymers appear and show large value in the application which avoid phase separation, simplify the fabrication process and is suitable for preparing large-area flexible devices. On this basis, the research work are carried out as follows:1. Iridium(Ⅲ) complexes introduced to the hyperbranched structure with large steric hindrance could be separated by host chains that effectively restrained the triplet-triplet annihilation. On this basis, tris[1-(4-bromophenyl)-isoquinolinato-C2,N]iridium(III) [Ir(piqBr)3] was designed and synthesized as red emitter reaction monomer. Subsequently, red emitter Ir(piq)3 was covalently connected with polyfluorene segments as blue emitter, and a series of double-color white hyperbranched conjugated polymers were obtained with higher fluorescence quantum yield(57 %~77 %). Among all devices, the device of PF-Ir(piq)3100(0.1 mol% Ir(piq)3) exhibited the best Commission Internationale de l’Eclairage(CIE) coordinate of(0.30, 0.23) closed to the pure white light(0.33, 0.33) with maximum luminance of 824 cd/m2, and maximum current efficiency of 1.97 cd/A.2. The yield of Ir(piq Br)3 was low which would increase the cost of EL materials. Therefore, bis[1-(4-bromophenyl)-isoquinolinato][3-(2-pyridyl)-5-(4-bromophenyl)-1,2,4-triazole]iridium(III) [Ir(piqBr)2(pytzphBr)] with higher yield was designed and synthesized. Double-color white hyperbranched conjugated polymers were synthesized with Ir(piq)2(pytzph) as red cores and PF as blue backbone. When the content of Ir(piq)2(pytzph) was 0.1 mol%, hyperbranched PF-Ir(piq)2(pytzph)100 exhibited better CIE coordinate of(0.25, 0.27) with maximum luminance of 2468 cd/m2, and maximum current efficiency of 1.73 cd/A which proved that different red iridium(III) complexes could realize red emission in the hyperbranched conjugated polymers. Meanwhile, we had synthesized linear polymers Linear PF-Ir(piq)2(pytzph)m with Ir(piq)2(pytzph) incorporated to PF backbone by main ligands and linear polymers End capped PF-Ir(piq)2(pytzph)m with Ir(piq)2(pytzph) as the end capped groups by auxiliary ligand.3. EL spectra of double-color white hyperbranched conjugated polymers were not saturated owing to the loss at 520~580 nm that influenced the quality of white-light emission. Therefore, chromophoric groups with emission peaks at 520~580 nm should be introduced to the hyperbranched conjugated polymers to realize more saturated EL spectra. Poly[(9,9-dioctylfluorene-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,7-diyl)](PFBT) was a good green material which could be introduced into the polyfluorene-based hyperbranched conjugated polymer with red Ir(piq)3 as the cores, and then a series of triple-color hyperbranched conjugated polymers were obtained. The synthesized polymers had good thermostability, photophysical properties, electrochemical properties and film forming ability. The diode of PF-BT250-Ir(piq)325(0.25 mol% BT and 0.025 mol% Ir(piq)3) exhibited better CIE coordinate of(0.32, 0.35), and EL spectra covered the whole visible region with maximum luminance of 3267 cd/m2 and maximum current efficiency of 1.60 cd/A。4. The hyperbranched polymers with PFBT as green emission had more saturated EL spectra, however, the current efficiency was low. In order to improve the EL properties, green phosphorescent iridium( Ⅲ) complexes bis(2-phenylpyridine)[3-(2-pyridyl)-5-phenyl-1,2,4-triazole] iridium(III) [Ir(ppy)2(pytzph)] were designed and synthesized which could be introduced into the hyperbranched conjugated polymers to obtain PF-Ir(ppy)2(pytzph)mIr(piq)2(pytzph)n in which green and red iridium(Ⅲ) complexes acted as the cores, respectively, and blue polyfluorene acted as the backbone. The energy transfer from Ir(ppy)2(pytzph) to Ir(piq)2(pytzph) could realize by intermediate PF segment. Among the white polymers, PF-Ir(ppy)2(pytzph)25-Ir(piq)2(pytzph)5(0.25 mol% Ir(ppy)2(pytzph) and 0.05 mol% Ir(piq)2(pytzph)) exhibited excellent EL properties with a CIE coordinate of(0.31, 0.34), color rendering index(CRI) of 92, maximum current efficiency of 7.81 cd/A and maximum luminance of 6030 cd/m2. The introduction of green phosphorescent iridium(Ⅲ) complexes improves the EL performance.In summary, double- and triple-color white hyperbranched conjugated polymers with phosphorescent iridium( Ⅲ) complexes as the cores were designed and synthesized. These hyperbranced conjugated polymers have large steric hindrance which could restrain the triplet-triplet annihilation of iridium(Ⅲ) complexes and improve the EL performance. Phosphorescent iridium(Ⅲ) complexes incorporated to the main chains of hyperbranced structure could impove the energy transfer efficiency, meanwhile, the white hyperbranched conjugated polymers with green iridium(Ⅲ) complexes as the cores have shown the best EL performance. The white hyperbranched conjugated polymers as a kind of single white molecules have large value in the application which would be a promising EL materials.更多还原