摘要
作为空穴传输材料,三芳胺类化合物具有较好的给电子性、较低的离子化电位、较高的空穴迁移率(一般约在10~(-3)-10~(-5) cm~2/V·s)、较好的溶解性与无定形成膜性、较强的荧光性能与光稳定性;作为发光材料,其强的紫外—可见区域的吸收以及蓝色发光可以满足蓝色电致发光材料的要求。因此,三芳胺类有机电致发光材料成为该领域的研究热点之一。
在分析和总结文献的基础上,本论文主要完成了以下两个方面的研究内容:1目标化合物的合成:(1)以芴为原料,设计合成了7个硝基、溴代、硝基溴代芴酮衍生物(9b-9h),并对部分化合物的合成工艺、分析分离方法进行了系统的研究,与现有的同类化合物的合成工艺相比,本论文研究建立的工艺技术具有成本低廉、绿色环保、高效低耗、操作安全等突出优点,易实现工业化,具有很好的应用开发前景;(2)以三苯胺和多聚甲醛为原料,通过胺醛缩合反应合成了三苯胺-多聚甲醛缩聚物(1a),对其合成条件进行了优化选择,并对聚合物中含有的亚甲基进行分子修饰,引入羰基、乙烯基、苯乙烯基、芴基等基团,合成了12种主链含有三苯胺链段的聚合物(2a-21);(3)以4-甲酰基三苯胺为原料,分别通过Wittig反应和活泼亚甲基化合物与醛酮类化合物的缩合反应合成了7个苯乙烯基三苯胺类衍生物(4a-4g),并通过胺醛缩合反应合成了6种相应的苯乙烯基三苯胺-多聚甲醛缩聚物(5a-5f)。所合成的中间体和目标化合物的结构都通过了红外、核磁、质谱、元素分析的表征。2对所合成的目标化合物的光电性能进行了初步研究:(1)以三苯胺-多聚甲醛缩聚物(1a)为原料合成的12种主链含有三苯胺链段的聚合物(2a-21)与三苯胺-多聚甲醛缩聚物相比,最大紫外-可见吸收波长和荧光发射波长都发生了明显的红移,除氧化修饰产物2a、对甲苯甲醛修饰产物2c和4-甲酰基三苯胺修饰产物2d发出黄绿色荧光外,其他9种聚合物都发出450-500nm的蓝色荧光;(2) 7个苯乙烯基三苯胺类衍生物(4a-4g)的紫外-可见最大吸收波长在370-430nm之间,并随溶剂极性的增大,紫外-可见吸收波长发生蓝移,荧光发射波长发生红移,同时斯托克位移增大。在不同溶剂中受光激发时,除硝基取代的化合物发出强烈的红色荧光外,其他6个化合物均发出440-500nm的强烈蓝色荧光。6种苯乙烯基三苯胺-多聚甲醛缩聚物5a-5f与小分子单体相比紫外-可见最大吸收波长吸光强度降低,荧光发射波长发生红移:(3)苯乙烯基三苯胺类衍生物(4a-4g)、聚合物2a和苯乙烯基三苯胺-多聚甲醛缩聚物5a～5c的带隙(Eg)为2.41～3.00eV,电离势(P_I)为5.45～5.92eV,电子亲和势(E_A)为2.60～3.37eV。数据表明,合成出的部分聚合物空穴传输性能优良,且具有较好的荧光性能,有望成为优良的空穴高效注入和传输的有机电致发光材料。
Triphenylamine derivatives as hole-transporting materials possess many excellent features such as better ability to supply electron,lower ionization potential,high hole-transporting rate,good dissolubility and amorphous film-forming ability,strong fluorescence and light stability;as light emitting materials,their strong absorption in UV-visible band and blue light emitting can meet the requirement of blue light electroluminescence materials.Therefore,organic electroluminescence materials based on triphenylamine are one of the research forefronts in the field of optoelectronic information materials.
Based on the full and careful analysis and investigation of a lot related literatures,we carried out the work including the following two aspects:1 Organic synthesis:(1) Seven bromo-,nitro- and bromonitrofluorenones(9b-9h) were synthesized respectively.The synthesis process and the methods of analysis and separation for part of the synthesized compounds were studied.Comparing with reported synthesis process,there are many outstanding advantages in our preparation method such as cost-effective,environment -friendly as well as better operational safety,and the newly-developed method is easily industrialized and shows good development and application prospects;(2) Using triphenylamine and paraform as starting materials,triphenylamine-paraform condensation polymer(1a) was synthesized by amine aldehyde condensation and the synthetic condition was optimized.Twelve polymers(2a-21) modified by introducing carbonyl,vinyl,styryl, flourenyl and other groups into methylene were synthesized;(3) Employing 4-formyl-tripheny-lamine as starting material,seven monomers(4a-4g) containing styryl triphenylamine were synthesized by Wittig reaction and the condensation reaction of active methylene compounds with aldehydes,and the six styryl triphenylamine-paraform condensation polymer(5a-5f) were synthesized from the above synthesized monomers respectively by amine aldehyde condensation reaction.All the synthesized compounds were characterized by IR,NMR,MS and elementary analysis.2 Investigation on the optical properties of the synthesized compounds:(1) When the twelve modified polymers (2a-21)compared with their starting material of triphenylamine-paraform condensation polymer,their UV-visible maximum absorption wavelength and the fluorescence emission wavelength were both markedly red-shifted.Nine polymers emitted blue fluorescence while the oxidation modified polymer(2a),the p-tolualdehyde modified polymer(2c) and the 4-formyl-triphenylamine modified polymer(2d) emitted olivine fluorescence;(2) The UV-visible maximum absorption wavelengths of the seven styryl triphenylamine monomers(4a-4g) were at 370-430nm.As the polarity of solvent increases, the UV-visible absorption was blue-shifted and the fluorescence emission wavelength was red-shifted,at the same time,Stark shift increased.In different solvents,six monomers emitted strong blue fluorescence at 440-500nm,whereas the nitro monomer emitted strong red fluorescence.Comparing the six tyryl triphenylamine-paraform condensation polymers(5a-5f) with their monomers,their UV-visible absorption strength were decreased and the fluorescence emission absorption were red-shifted;(3) The band gaps(Eg),ionization potentials(P_1) and electron affinity(E_A) of styryl triphenylamine monomers(4a-4g),polymer 2a and 5a-5c were 2.41-3.00eV,5.45-5.92eV and 2.60-3.37eV, respectively.The experiment data indicate that these compounds are good candidates as electroluminescent materials with good hole-transport property and photoluminescence property.
引文
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