PPV系高分子具有優良的螢光特性與適當的半導性,是最被廣為應用於電激發光的共軛高分子,因具有低成本、製程簡易故廣受學術界與工業界注目。其中聚2-甲氧基-5-(2-乙基-己氧基)對苯乙烯(MEH-PPV)在高分子材料中,因其具有溶於一般有機溶劑,而其製成元件具低驅動電壓與高發光效率之優點。 本論文主要分為兩個部分:第一部份是單體在不同混合比例溶劑中進行聚合反應。由於單體在THF中進行聚合反應會產生凝膠化的現象,而在DMF中進行聚合反應則會生成低分子量的高分子聚合物,以上兩者情形都會對元件光電性質有不利的影響。因此我們將以混合溶劑進行聚合反應,探討不同反應環境對於分子量大小及分子量分佈的影響。 第二部分則是混摻不同重量比例的液晶小分子(7CB)到MEH-PPV高分子中,用旋轉塗佈至玻璃基材,在真空下,相對於過去論文中使用高溫迴火的方式,我們改採以低溫迴火及液晶小分子自排列的特性製成元件,藉由偏光顯微鏡(POM)觀察其排列形態的變化;電致發光光譜儀(EL)量測高分子薄膜的電致發光光譜。探討加入液晶小分子對高分子影響之相關性。
The study of this thesis has shown the importance of two features. The first is the relation between mixed-solvent influence and molecular weight of poly(2-methoxy-5- (2’-ethylhexyloxy) -1,4-phenylenevinylene) (MEH-PPV). The second is the morphology about MEH-PPV blending with the liquid crystal molecule. Part I:The solvents of the first system consists of tetrahydrofuran (THF) and N,N-Dimethylformamide (DMF). The molecular weight of MEH-PPV, can be controlled by the various ratios of DMF. The polydispersity index (PDI) of MEH-PPV can be controlled, too. The molecular weight of MEH-PPV is decreased when the weight ratio of THF increases. Part II:The research of the second system is about MEH-PPV blending with 4-Cyano-4'-N-Heptylbiphenyl (7CB). The morphology of the system has been studied by polarized optical microscope (POM). The changes of the morphology in the blending system is dependent on the weight ratio of 7CB. The optimal opto-electronic properties of the system can be found out. It is an optimal weight ratio that the weight ratio of 7CB is 0.4.