新型含芴共聚物之合成及其在高分子電激發光二極體之應用

Abstract

本研究的主要目的在於合成以fluorene為基礎的共軛高分子及其在高分子發光二極體之應用，並探討反應條件的改變對所合成出之polyfluorene平均分子量的影響。首先，本研究的第一部分利用2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxanbrolan-2-yl)-9,9-dihexylfluorene分別與9,9-bis(2-cyanoethyl)-2,7-dibromofluorene和9,9-bis(2-cyano- ethyl)-2,7-diiodofluorene進行Suzuki coupling合成出poly[2,7-(9,9- dihexylfluorene)-alt-2,7-[9,9-bis(2-cyanoethyl)fluorene]] (P2)。結果證實，在進行聚合反應時使用9,9-bis(2-cyanoethyl)-2,7-diiodofluorene比9,9-bis(2- cyanoethyl)-2,7-dibromofluorene可以得到較高分子量的聚合物。在本研究的第二部分，我們合成出一系列含有9,9-dihexyl- fluorene、triarylamine(s)(M6∼M8)和 ethylenedioxythioph- ene 團基的共聚合物(P3∼P7)。這些含有triarylamine團基的聚合物(P3∼P7)都有較高的玻璃轉移溫度。聚合物P2為一最大放射波長在550 nm的綠光材料;聚合物P3∼P6的最大放射波長則在436 nm∼496 nm之間，分別為發藍光與藍綠光的材料;聚合物P7包含triarylamine與ethylene- dioxythiophene團基，其最大放射波長在486 nm且在 516 nm處有一肩帶。本研究亦製作了結構為ITO/PEDOT/polymer/Ca(Al)的雙層發光二極體元件，並探討其發光特性。經過測試後，結果證實當我們在高分子主鏈上導入triarylamine團基，可以降低元件的驅動電壓。

The goal of this study is aimed to synthesize fluorene-based conjugated polymers for the application in polymer light emitting diodes ( PLEDs ) . The correlation between reaction conditions and the average molecular weight of the obtained polyfluorenes was investigated. In the first part of this study, we synthesized poly[2,7-(9,9-dihexylfluorene)-alt- 2,7-[9,9-bis(2-cyanoethyl)fluorene]] (P2) via Suzuki coupling of 2,7-Bis- (4,4,5,5-tetramethyl-1,3,2-dioxanbrolan-2-yl)-9,9-dihexylfluorene with 9,9-Bis(2-cyanoethyl)-2,7-dibromofluorene and 9,9-Bis(2-cyanoethyl)- 2,7-diiodofluorene respectively. The results demonstrate that a higher molecular weight polymer was obtained when 9,9-Bis(2-cyanoethyl)- 2,7-diiodofluorene instead of 9,9-Bis(2-cyanoethyl)-2,7-dibromofluorene was used. In the second part of this study, we synthesized a series of conjugated copolymers(P3∼P7) comprised of 9,9-dihexylfluorene, triarylamine(s)(M6∼M8) and ethylenedioxythiophene moieties. All polymers(P3∼P7) containing triarylamine moieties show much higher glass transition temperatures. Polymer P2 exhibits a strong green emission at 550 nm while polymers P3∼P6 exhibit blue to blue green emission from 436 nm to 496 nm. Polymer P7 which containing both triarylamine and ethylenedioxythiophene moieties exhibits both emission peak at 486 and 516 nm. Two-layer light-emitting devices with a simple ITO/PEDOT/polymer/Ca(Al) configuration were fabricated and characterized. The results demonstrate that the device driving voltage can be decreased when a triarylamine moiety is included in the copolyfluorene backbone.