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Title: Synthesis of blue fluorescent polymers for light emitting diodes
Author: Chang, S. M.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 1998
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The main objective of the project was to synthesise electroluminescent polymers for blue light-emitting diodes (LEDs) which are a particularly attractive target for research. Blue inorganic LEDs only recently became available, and polymers offer the advantages of low cost and solution processibility. This facilities the fabrication of large-area devices by spin-coating techniques. The following dissertation is comprised of five chapters. Chapter 1 gives a general overview of the application of conjugated polymers in LEDs. Chapter 2 is the literature cited on organic blue electroluminescent (EL) materials. Chapter 3 describes the synthesis of blue-shifted emissive polymers based on poly(phenylene vinylene) (PPV), by introducing meta-linkages into the backbone to reduce the average conjugation length, and hence shift emission to the blue region of the spectrum, for example, polymer 125 has a light-blue emission. A model oligomer 184 was prepared by the Wittig-Horner reaction and the results of a single crystal X-ray analysis showed that the CF3-substitents twisted the lateral phenyls out of plane by an angle of 70°. In Chapter 4 the blue fluorescent polyarylenes are prepared by nickel or palladium catalysed cross-coupling reactions. Polymer 205 exhibited a strong blue fluorescence containing a chiral soluble side chain and an unsubstituted double bond. Polymer 208 containing a sulphonate side chain was water soluble. Chapter 5 reports the evaluation of these synthetic materials by the study of the photoluminescence (PL) emission, the preliminary EL device fabrication. Photostability tests and electrochemistry measurements were also carried out. Polyphenylene-based polymers 204 and 205 exhibited enhanced photostability and higher PL efficiencies compared with the poly(phenylene vinylene) analogues 119, 124 and 125.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available