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Title: Development of Advanced Dendritic Materials
Author: Ito, Fumiaki
ISNI:       0000 0001 3587 5454
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2007
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Electroactive organic materials have been making progress towards technological applications such as organic light-emitting diodes (OLEDs). In particular, use of electroluminescent dendritic materials in OLEDs show significant promise for a wide range of practical requirements because of their macromolecular structure being highly controllable with regard to both the chemical and physical properties. This thesis describes the development of synthetic approaches to novel phosphorescent dendrimers containing either 1,3,S-triazine or benzimidazole dendrons with the aim to develop materials in which the high electron affinity of the dendrons would be higher than the core and hence facilit~te electron transport through emissive layers in OLEDs. At an early stage, significant difficulties in the stability of triazine derivatives were identified, requiring an introduction of stabilising groups onto triazine rings. With analysis of reactivity and stability of 1,3,S-triazine derivatives, a promising structural modification of using carbzolyl moieties attached to triazine-branching units was discovered. It was found that triazine-based dendronised ligands could not be complexed to iridium(III) to give a single compound due to multiple co-ordination sites. The introduction of an amine linker solved this problem with the dendrons being added to the already fonned complex. 2-Ethylhexyloxy surface groupS were found to increase the solubility of the dendrimers in common organic solvents and also decreased intermolecular interactions of the emissive cores. Dendrimers with benzimidazolyl units in the dendrons were also prepared. that the redox processes were also dendron-dependent. Molecular orbital calculations quantum yield was dependent on the dendron type. Electrochemical analysis showed The photophysical properties of the dendrimers showed that the photoluminescence of the orbital energies and distribution were consistent with the observed properties. containing a light-emitting dendrimer comprised of the dendrimer 114 blended with Finally, OLED devices were fabricated using the soluble dendrimers. The highest external quantum efficiency of 5.4% at 100 cdlcm2 was observed for a bilayer device 4,4'_bis(N-carbazolyl)biphenyl (CBP) as a host.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available