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Title: Novel architectures for polymer light-emitting diodes
Author: Ho, P. K. H.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2000
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This dissertation work aims to develop novel optoelectronic polymer device architectures through appropriate control of the interfacial and bulk structures of the semiconducting polymer. The two approaches developed here are the hole-injection interlayer engineering via the layer-by-layer polyelectrolyte assembly, and refractive-index engineering via the use of polymer-inorganic nanocomposites. The poly-electrolyte assembly route enables vertical interfacial structuring of the electronic properties to be achieved at the anode contact for improved hole injection and electron confinement. The development of the nanocomposites provides solution-processable photonic building blocks that are semiconducting and that could provide optical feedback in polymer devices. Both of these developments have made possible new high-performance device architectures. For example, polymer light-emitting diodes (LEDs) with efficiencies of 20 cd/A in the green spectral region (estimated internal quantum yield, 15-20% photon/electron), and polymer microcavity LEDs with emission full-width-at-half-maximum of 25 nm and less have been demonstrated. This dissertation also addresses a few of the scientific issues encountered in the course of the work. The relationship between external and internal electroluminescence quantum yields of these LEDs is analysed, and the role played by optical properties of the metal cathode-reflector delineated. The effects of embedding SiO2 nanoparticles on the optical, electronic and morphological properties of the poly(p-phenylenevinylene) matrix, together with the extent of increased localisation of its p-electrons, are also studied.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available