| Summary: | 碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 94 === 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.
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