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Title: Carbon nanotubes as a material for functional inks
Author: Graddage, Neil
Awarding Body: Swansea University
Current Institution: Swansea University
Date of Award: 2012
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Carbon nanotubes (CNTs) have been proposed as a material for use in printed electronics for a number of years. The potential to exploit the unique electrical and mechanical properties of these structures on the macro-scale is appealing; however there are a number of hurdles to overcome. Printing allows the deposition of CNT networks, the properties of which are governed by the CNT type and network density. The formulation of a suitable ink and deposition of a film with specific properties is challenging, and the work described in this thesis is concentrated on two specific areas, CNT ink development and CNT based device production. The CNT ink was developed by identifying key ink and dried film parameters for characterisation and assessing the effect of several major variables, namely the resin material, resin concentration, processing temperature, CNT concentration, CNT functionality and processing energy. A suitable research ink was developed and optimised using N-methyl-2-pyrrolidone as the solvent and polyvinyl alcohol as the resin at a concentration ratio of 1:1 with the CNT content. The effects of CNT concentration, CNT functionality and processing energy are shown to be interdependent. This is among the first reported studies to investigate the dependence of these factors upon a CNT ink for roll-to-roll processing. This ink system was then used in the production of CNT based thin film transistor (TFT) devices using flexography. Initially the concept was proven using MWCNTs. The design was then refined and devices were produced using SWCNTs at varying network densities. It was seen that the printing of CNT based devices using flexography is feasible, though careful control of the CNT network density is required to achieve suitable device performance. This is the first reported production of TFTs using flexography, and the first reported use of flexograi)hy to deposit CNTs.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Nanotubes ; Ink ; Printing ; Nanotechnology