含三個共軛環及五個共軛環光電分子材料之研究

Abstract

本論文研究的光電分子材料是三環和五環的共軛有機分子。藉由改變其側鏈及末端取代基、分子的共軛長度和與酸搭配形成氫鍵錯合物等結構變化，並利用熱微差掃描卡計(DSC)和偏光顯微鏡(POM)做相關液晶行為的量測。由本身有液晶相的分子和氫鍵錯合物，研究發現適當長度的側端和末端長碳鍊有助於液晶相（向列相）的生成，但過長則會使液晶相的範圍縮短 ; 且末端官能機改成pyridine雜環的分子其液晶性質普遍不佳，但在形成氫鍵錯合物後，就可生成不錯的液晶相。 另針對有螢光性質的分子作UV-vis(abs)，Phtoluminescence-solution，Photoluminescence-pure film，Photoluminescence-blend film，Electro- luminescence-blend film的性質探討。共軛有機分子側端和末端長碳鍊的改變，對螢光體而言並沒有太大的影響，在末端官能機改成pyridine雜環時，會有一明顯的紅位移，且其在形成氫鍵錯合物後，又可觀察出較未配氫鍵前有明顯的紅位移行為，當氫鍵錯合物搭配不同的酸則有不同的位移情形，可藉此現象調配我們想要的光色。 最後找出同時具有螢光和液晶行為的分子，偵測其在液晶相（nematic）時的螢光特性，證明其在放入平行配向cell中配向後發出的光為偏極光，成功地將液晶相製備出有機發偏極光的特性。研究發現顯示：發光光譜及偏極光偏極效率受共軛液晶分子所存在的相及形成氫鍵與否之影響極鉅。

This report is to synthesize and investigate electro-optical molecular materials containing three- and five-conjugated rings. By modification of the side chains, end groups, and conjugation lengths of the conjugated molecules, along with the donor acids in the H-bonded complexes, we are able to characterize their mesogenic behavior by DSC and POM. The measurements reveal that appropriate lengths of the side chains and end groups result in better liquid crystallinity (the nematic phase); however, the range of the mesogenic phase is reduced at longer lengths of above chains. Moreover, molecules containing pyridine-substituted end groups have poor liquid crystallinity, but their mesogenic properties are improved by the construction of H-bonded complexes. Due to the fluorescent nature of the conjugated molecules, we also investigate their photoluminescent (PL) and electroluminescent (EL) properties by UV-vis (abs), PL (solution, pure film, and blend film), and EL (blend film) measurements. These measurements reveal that the tuning of side chains and end groups would not affect their fluorescence properties significantly. However, the pyridine-substituted group and the H-bonded interaction of the complex result in a red-shift and a further red-shift, respectively, of the photo- and electro-luminescent peaks. The emission peaks of the conjugated molecules are shifted by using of various acids as proton donors, and thus the emission color is easy to be tuned by H-bonding . To conclude this report, we have developed novel fluorescent conjugated compounds and their H-bonded complexes possessing mesogenic properties, which can generate polarized light in the aligned nematic phase by using parallel alignment cells. We also have succeed in producing polarized photoluminescent cells by application of the liquid crystalline phase. The emission peaks and polarization efficiency are greatly influenced by the existing phases and the formation of H-bonds in the conjugated molecules .