以四氯駢苯二醯亞胺作為架橋之聚(1,4-仲苯乙烯)超分枝高分子之合成及光電性質研究

Abstract

摘要 本研究之目的在合成出以四氯駢苯二醯亞胺作為架橋之聚(1,4-仲苯乙烯)超分枝共軛高分子，並探討其光學、電性及電化學性質。本研究另製備以柔軟碳鏈為架橋之超分支高分子，以做為對照之用。 所有高分子之數量平均分子量經測定為1.0-2.65×105 g/mol，重量平均分子量則為2.1-4.7×105 g/mol，經引入雙頭單體所得之高分子分子量增加幾乎到達兩倍，而DP6-PPV衍生物其分子量則因剛硬苯環團基造成之立體阻礙，分子量僅略增兩成。CV結果顯示四氯駢苯二醯亞胺的引入，導致其還原電位明顯下降；DP6-PPV衍生物引入超分支結構後，其氧化電位亦明顯下降。 所有超分枝高分子其玻璃轉移溫度及裂解溫度在引入四氯駢苯二醯亞胺支架橋後有顯著上升。DP6-PPV超分枝高分子於薄膜態之UV-vis吸收及PL放射光譜均較純DP6-PPV藍位移，顯示其優異之抗堆疊特性。MEH-PPV超分枝高分子其PL放射其最大峰值無顯著差異，但其肩峰的放射相較於MEH-PPV極不明顯，顯示超分枝結構可以打亂MEH-PPV之有序排列，但無法防止堆疊。 將所有高分子做成雙層元件並測量其性質後，發現HDD因較低之注入能障使其驅動電壓降低，亮度與效率分別達到282 cd/m2與0.008 cd/A。而HPM因perylene引入使其傾向於電子注入，進而增加電子電洞對再結合而放光之機率，其亮度與效率分別達到342 cd/m2與0.035 cd/A，以上結果說明了這些高分子材料具有應用在發光元件之潛力。

Abstract The goal of this research is to synthesize the hyperbranched poly(1,4-phenylene vinylene) derivatives containing tetrachloro- perylene bisimide as bridging moiety. The optical, electrical, and electrochemical properties were investigated. The polymers containing soft alkyl spacer as bridging moiety were also synthesized for comparison. The number-average molecular weights of the hyperbranched polymers are in the range of 1.0-2.65×105 g/mol, while weight-average molecular weights are in the range of 2.1-4.7×105 g/mol. The molecular weight of the hyperbranched polymers doubles compared to the corresponding homopolymer, while DP6-PPV derivatives show only 20% increase in molecular weight. This can be attributed to the steric hindrance brought by rigid substituents. The CV results indicate that introducing tetrachloroperylene bisimide lowers the reduction potential. The oxidation potential is also lowered by introduction of hyperbranched architecture. The glass transition and decomposition temperatures of the polymers are raised after incorporating rigid tetrachloro- perylene bisimide. The UV-vis absorption and PL emission of DP6-PPV-based hyperbranched polymers show blue-shifted characteristic compared to DP6-PPV homopolymer in film state, indicative of prohibiting aggregation of hyperbranched polymers. The max PL emission band of MEH-PPV-based hyperbranched polymers are located at the same wavelength compared to MEH-PPV, yet the shoulder emission band is much less significant, implying disturbance of ordered alignment of MEH-PPV chains after introducing hyperbranched structure. Double-layer PLED devices with the configuration of ITO/PEDOT/ polymer/Al were fabricated and evaluated. The device based on HDD showed a lower turn-on voltage because of smaller injection barrier, and it reached the highest brightness and current yield of 282 cd/m2 and 0.008 cd/A, respectively. The tendency of electron injection leads to a higher probability of the carrier recombination in HPM-based device, and it reached the highest brightness and current yield of 342 cd/m2 and 0.035 cd/A, respectively. The above results indicate that these materials are potential candidates for the application in light-emitting devices.