| Summary: | 碩士 === 國立成功大學 === 化學工程學系 === 87 === Organic light emitting diodes (OLEDs) have been recently concerned. However, emission efficiency of the electroluminescent device needs further improvement. At present it is circumvented by mutilayer strategy, i.e., insertion of electron transport layer (ETL) and hole transport layer (HTL) between electrodes and emission polymer layer. In this work, electron transporting chromophores were introduced to emission polymer to increase its electron affinity. Several emission chromophores also were synthesized to polycondensate with electron transporting chromophores. The influence of structure on optoelectric properties was investigated in detail.
2,5-Bis- (4-fluorophenyl)-1,3,4-oxadiazole and 4, 4''-dihydroxystilbene derivatives were used as electron transport and emission monomers, respectively. The 4, 4''-dihydroxystilbene derivatives, which contain biphenylylene or 1, 4-naphthalene, were synthesized by Horner-Wadsworth-Emmons olefination reaction. The emission units exhibit blue light as expected. Aromatic polyethers were obtained by nucleophilic displacement reaction of oxadiazole-activated bis(halide) monomers with bis(phenol) monomers. Moreover, two polymers containing octanethylene chain instead of electron transport unit were also synthesized for comparison. All the resulted polymers are thermally stable below 400℃. The absorption maxima of these polymers are 305 nm∼350 nm, while the photoluminescence maxima are 382 nm∼446 nm. The polymers containing electron transporting oxadiazole indeed show extra reduction potentials in CV measurements.
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