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Title: Towards high-speed AFM redox-writing of tetra(aniline) thin films
Author: Brown, Benjamin Paul
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2013
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Oligo(aniline)s, oligomers of the conducting polymer poly(aniline}, retain the redox- and pHswitchable insulating and conducting states that have led to the wide use of poly(aniline). However, the oligo(aniline)s offer a substantial improvement in both processability and tunability of the structure, molecular architecture and optoelectronic properties. The synthesis of an extensive family of oligo(aniline) materials has been refined in Bristol during the last few years. For these materials to be developed for use in devices, methods for the preparation and modification of high-quality thin films with smooth interfaces need to be developed. The key aim of this work was to carry out high-speed conductive atomic force microscope (cAFM) redox writing on a thin film of oligo(anilines}, inducing local changes in the oxidation state - and hence conductivity - of the film. This would offer a single-step method of creating arbitrary-shaped conducting and insulating features on the film in ambient conditions with nanoscale resolution. To achieve this, 3 key objectives were identified: 1) the preparation and characterization of a TANI thin film, 2) demonstration and refinement of the cAFM redox writing process using a conventional cAFM system and 3) expanding the capabilities of the technique using a high-speed AFM. The research carried out to achieve these objectives is described within this thesis. The preparation of doped tetra(aniline) (TANI) films has been extensively investigated. Thin «20 nm) films of tetra(aniline) doped with camphor sulfonic acid (CSA) have been prepared on HOPG using simple drop-casting techniques. The (cAFM) redox-writing process was then investigated and refined on these doped films. Using the technique, local reversible changes in conductance have been induced in the film. cAFM, Secondary Ion Mass Spectrometry (SIMS) and X-ray Photoelectron Spectroscopy (XPS) have been used to characterise the physical and electronic properties of the films (as-produced and after redox writing). The analysis proved consistent with the proposed electrochemical change in the film. A commercial cAFM system was then modified with a high-speed nanopositioner as a highspeed scanning stage to fabricate arbitrary-shaped conductance features with <100 nm feature size using the cAFM redox-writing technique.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available