基于芴基超支化聚合物的设计、制备与性能

【作者】 汤多峰；

【导师】 韦玮；

【作者基本信息】 复旦大学 ， 材料物理与化学， 2008， 博士

【摘要】 对于聚合物在有机电子学方面应用的飞速发展,本论文综述了基于芴的可交联、超支化聚合物在OLED中的应用以及聚合物的非线性性能,并提出在这些领域中需要解决的问题。1.在以芴为主体的发光材料中,稳定性是一个非常重要的问题;2.如何实现超支化聚合物合成上的方便实现,以达到在引入第三基团的同时不会改变超支化聚合物稳定性的特点;3.在可交联聚合物中,如何在不影响发光稳定性的情况下实现交联在工艺上的易于实现;4.有机共轭超支化聚合物在非线性材料中的应用还非常少,将所合成的聚合物进行非线性性能的测试不仅可以加深对非线性现象的认识,而且可以为后来者指出如何在现有材料的基础上进行超支化聚合物的设计指明方向。基于此,本论文设计并制备了以苯、嗯二唑、噻吩、Truxene为核的可交联超支化聚合物,并进行了电致发光器件、非线性材料等方面的性能研究。具体的各部分内容摘要如下。一、制备了以苯、噁二唑、噻吩和Truxene为核的四种可交联超支化聚合物。对可交联单体得到了与文献报导的不一样的状态,并通过DSC方法对可交联单体6的熔点和熔融焓进行了表征。对所合成聚合物通过一系列的测试手段进行了表征,发现含有较高核含量的超支化聚合物P2、P4、P6和P8具有优良的热稳定性,光谱特性较佳。而当核的含量较低时,其光谱特性接近于线形聚芴,并且具有明显的g带。电化学分析表明,随着核含量的提高,聚合物的带隙变大,而噁二唑的引入可以降低聚合物的LUMO值。对聚合物的结构分析表明得到了正确的产物,并且性能可以满足应用的要求。二、对所合成的超支化聚合物进行了绝对量子效率、荧光显微镜、AFM和电致发光器件表征。结果表明,大幅度提高核的含量虽然有利于光谱稳定性,但是由于共轭打断使得共轭长度变小,造成绝对量子效率的降低;荧光显微镜的结果表明,聚合物具有良好的成膜性;经过200℃空气中退火3h后,支化程度较高的P2、P4、P6和P8表现出了较好的成膜稳定性。AFM结果表明,在聚合物中加入交联引发剂时,THF和甲苯具有不同的溶解效果,THF更加有利于聚合物的成膜;交联后膜的表面粗糙度变大。器件分析表明,交联有利于提高器件稳定性,聚合物的电致发光光谱与光致发光光谱相一致。器件效率不高归结为器件没有进行优化以及产物纯度不高所致。三、对所得到的聚合物进行了非线性光学性能测试。由于聚合物自身没有带发色团,仅仅靠自身的共轭结构产生非线性效应,因此整体上二阶非线性效应较弱;而通过对P2和P6的二次电光系数的测试发现,由于噻吩五元环相比苯的六元环而言对称性较差,因此在外场作用下表现出一定的三阶非线性效应,其值为K=5.68122×10^-15（m/V）²。四、对含铱配合物的超支化聚合物的制备及光电性能进行了初步的探索。核磁研究表明,铱配合物在聚合物中的含量与投料比近似。热分析表明,聚合物具有优良的热稳定性。荧光发射光谱显示,溶液中完全表现为芴的发射,形成固体膜后,发生能量转移,表现为铱配合物的发射。电化学表明聚合物的LUMO更接近于一般阴极材料的功函。制成结构为ITO/PEDOT∶PSS/P9/Ba/Al的器件后,最大亮度达到169cd/m²,电致发光的光谱与固体薄膜光致发光的光谱类似,都表现为铱配合物的发光,表明实现了聚合物三线态能量的完全利用。更多还原

【Abstract】 In this paper,the recent progress in crosslinkable polymer and hyperbranched polymer and their application in NLO material based on fluorene have been reviewed. Some problems in this field have been found,1.The problem of stability is very important in electroluminescent polymer based on fluorene.2.How to make the crosslink procedure convenient in making the device without worse the quality of the spectrum.3.How to easily synthesis the hyperbranched polymer in order to introduce the other functional group without worsen the device quality.4.There only are a few papers about the application of hyperbranched polymer in NLO material,it’s interesting to apply the synthesis hyperbranched polymer in NLO in order to reveal the relationship between function and structure.Based on these problems,the crosslinkable and hyperbranched polymers with the benzene,oxazdiazole,thiophene and Truxene as the core have been designed and synthesized.And the resulted polymers have also been applied in the electroluminescent device and NLO material.The detailed abstract of each part of this paper is listed below.1.The hyperbranched crosslinkable polymers with the benzene,oxazdiazole, thiophene and Truxene as the core have been synthesized respectively.The synthesized crosslinkable monomer has different state in room temperature with what has been reported in literature.The melting point and enthalpy was measured by DSC.The synthesized polymers were characterized and found P2,P4,P6 and P8 are well in thermostability.The resulted spectrum is well.For the polymer with lower content of the core,the spectrum is similar with what of the linear crosslinkable polyfluorene.The CV characterization showed that the energy gap increased with the increase of the content of the core.The introduction of oxadiazole is good for lowering the LUMO of the poymer.2.The intergraded sphere,luminescent microscope,AFM and device were used to characterize the synthesized hyperbranched polymer.Although the stability can be increased with the increase of the content of the core,the quantum efficiency is on the contrary.The luminescent microscope shows that:these polymers are well before annealing.After annealing in the air,the film of the linear crosslinkable polyfluorene is totally damaged,while the films of P2,P6 and P8 are still well. The AFM results show that the solubility of the initiator is different in THF and toluene.After crosslink,the RMS of these crosslinkable polymers increased.The device results show that crosslink procedure is favor to the stability of the spectrum.The electroluminescent spectrum is familiar with the one of photoluminescence.The relative lower efficiency is because of the impurity of the polymer and the simple device structure.3.The NLO effects of these polymers were tested by Mark-fringes method.The experiments results show that it is mainly from the conjugated structure.For the second EO effect,P2 and P6 show different behavior because of the different structure between benzene and thiophene.The second EO coefficient of P6 is K = 5.68122×10^-15（m / V）².4.The device and functionality of P9 with Ir complex have been explored.The content of the complex in polymer is analyzed through NMR.The thermo stability of polymer is very well.Analyzed by photoluminescence,the spectrum is very similar with polyfluorene in toluene while it is totally the emission of Ir complex in solid state.The LUMO of the polymer is very close to the work function of anode metal.With structure of ITO/PEDOT:PSS/P9/Ba/Al,the maximum brightness of the device is 169cd/m².The electroluminescence of P9 is similar with the photoluminescence one which shows the same triplet energy.更多还原