含樹枝狀側鏈取代基之聚(2,3-雙苯基乙烯)共聚物之合成及其在高分子電激發光元件上之應用

Abstract

本研究中成功的合成出三種含樹枝狀取代基之單體，分別為G1-DPM, G2-DPM 與G3-DPM。且利用Gilch route聚合法，以過量t-BuOK提供鹼性環境，與1,4-bis (bromomethyl)-2,5-dimethoxybenzene (DMe-M)及1,4-bis(bromomethyl)-2-phenyl-3-[p-(3,7-dimethyloctoxy) phenyl]benzene (OC10-DPM)，進行共聚合反應合成出共聚合物P1~P6，其最大放射峰介於538~548 nm範圍間，屬於黃綠色發光材料。 而第二部分中，則以G3-DPM為主體，分別與1,4-bis(bromomethyl)-2-methoxy-5-(3,7-dimethyloctyl)benzene(MDMO-M)、1,4-bis(bromomethyl)-2,5-methoxy benzene(DMe-M)、1,4-bis (bromomethyl)-2-methoxy-5-(3-ethylhexyl) benzene(MEH-M)進行共聚合反應，得到共聚合物P7~P12，最大放射峰介於549~568 nm之間，屬於黃綠光至黃光發光材料。由實驗結果可知，於PPV主鏈中導入含樹枝狀側鏈單體，可有效的減少材料由溶液態轉變為薄膜態時螢光光譜紅位移現象。而所合成之共聚物均具有相當高的分子量以及足夠的熱穩定性。 本研究亦製作了結構為ITO/PEDOT/Polymer/Ca(Al)之雙層有機電激發光二極體元件，並探討其發光特性。其中以P1為發光層之元件最大效率與亮度分別可達4.53 cd/A， 2114 cd/m2，此結果表示將適當的樹枝狀側鏈取代基 (G3-DPM)導入PPV共軛系統中，可有效避免高分子鏈堆疊，進而提升元件效率。而以P7為發光層之元件最大亮度可達5068 cd/m2效率為0.64 cd/A，顯示將G3-DPM與MDMO-M共聚以增加電洞傳輸能力，亦可有不錯的亮度表現。

In this study, three kinds of dendron containing monomers, i.e., G1-DPM, G2-DPM and G3-DPM were synthesized. The monomers were copolymerized with 1,4-bis(bromomethyl)-2,5-dimethoxybenzene (DMe- M) and 1,4-bis(bromomethyl)-2-phenyl-3-[p-(3,7-dimethyloctoxy)phenyl] benzene (OC10-DPM) via Gilch route using excess t-BuOK as base to yield dendron-containing poly(2,3-diphenyl-1,4-phenylene vinylene) (DP-PPVs) derivatives P1~P6. Polymers P1~P6 emitted yellow-greenish light between 538 and 548 nm. In the second part of this study, monomer G3-DPM was copolymerized with 1,4-bis(bromomethyl)-2-methoxy-5-(3,7-dimethyl octyl)benzene (MDMO-M), 1,4-bis(bromomethyl)-2,5-methoxybenzene (DMe-M), or 1,4-bis (bromomethyl)-2-methoxy-5-(3-ethylhexyl)benzene (MEH-M), to yield the dendron containing DP-PPV derivatives, P7~P12. Polymers P7~P12 exhibited yellow-greenish to yellow light from 549 to 568 nm. The results demonstrate that the incorporation of dendron groups into DP-PPV main chain could efficiently reduce the phenomenon of red-shift for these DP-PPV derivatives from solution to thin film state. All polymers synthesized in this study exhibited high molecular weights and excellent thermal stabilities. The double layer polymer light-emitting diode (PLED) devices with the configuration of ITO/PEDOT/emitting polymer/Ca(Al) were fabricated. A high efficient PLED device which was fabricated by using P1 as the emitting polymer. Its maximum external quantum efficiency and brightness are 4.53 cd/A and 2114 cd/m2. The results show that introducing dendron groups into the DP-PPV main chains can avoid chain aggregation, and therefore improve the performance of the device. The best PLED device was fabricated by using P7 as the emitting layer. Its maximum brightness and external quantum efficiency of P7 can reach 5068 cd/m2 and 0.64 cd/A. The results above reveal that MDMO-M was incorporated in the polymer main chains, which enhances the hole mobility of polymer P7.