Poly[2-(2-ethylhexyloxy)-5-methoxy-1,4-phenylene vinylene]-block-Poly (2,3-diphenyl-5-octyl-p-phenylene vinylene)(MEH-PPV-block-DPO-PPV)團狀共聚高分子之合成與光電性質之討論

Abstract

本研究是利用Wittig-Horner方法製備出含有MEH-PPV與DPO-PPV鏈段的團狀共聚物MEH-PPV-block-DPO-PPV，當兩種高分子鏈段均達飽和共軛鏈長時，可使此diblock copolymer有比純的MEH-PPV及DPO-PPV更好的發光效率；我們另外也用Witiig-Horner合出純的MEH-PPV、及DPO-PPV高分子，並利用NMR氫譜鑑定其結構，DSC、TGA判斷其熱性質。 我們利用控制反應機制與時間成功合成了diblock copolymer 及另外兩種高分子。三種高分子在溶液狀況下，DPO-PPV為藍綠光，MEH-PPV為橘紅光，而MEH-PPV-block-DPO-PPV為黃光，三種的螢光強度均很高。Witiig-Horner反應為醛基與磷基的縮合反應，所以聚合物分子量無法聚得很大。當我們製備為有機發光二極體時，MEH-PPV的起始電壓為3.9V，最大亮度在12.2V時有102 cd/m2時。MEH-PPV-block-DPO-PPV在三種高分子中，擁有最好的效率，其起始電壓3.1V，且在9V時可得最大亮度525 cd/m2。

We prepared poly[2-(2-ethylhexyloxy)-5-methoxy-1,4-phenylene vinylene ]-block-poly(2,3-diphenyl-5-octyl-p-phenylene vinylene(MEH-PPV-block- DPO-PPV) with MEH-PPV and DPO-PPV chain segments by Wittig-Horner reaction in this research . When this two polymer chian segments reach the saturation of conjugation length, it make diblock copolymer have better luminescence efficiency than pure MEH-PPV and DPO-PPV.Besides, we also prepared pure MEH-PPV and DPO-PPV for comparison . We used NMR to characterize these three polymer structures and DSC 、TGA to investigate their thermal properties. We synthesized successfully MEH-PPV 、DPO-PPV and their diblock copolymer by controlling the reaction temperature and time.In THF solution, DPO-PPV appeared blue-green,MEH-PPV orange-red and MEH-PPV-block- DPO-PPV yellow.The three polymers all exhibited bright photoluminescence.Wittig-Horner reaction is the condensation reaction of aldehyde and phosphonate ,but can’t synthesize higher molecular weight.Polymer with small molecular weight can’t form smooth film after spin coating instead the film had molecular defects that would affect luminous properties. As we fabricated polymer light emitting diodes(PLED),MEH-PPV has turn-on voltage at 3.9V and the largest luminance of 102 cd/m2 at 12.2V.MEH-PPV-block-DPO-PPV has the best efficiency among three polymers with the turn-on voltage at 3.1V,and has the bright luminance of 525cd/m2 at 9V.