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

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.