Manipulating Metal Oxides Properties by Plasma Based Synthesis Methods

Abstract

The main aim of this thesis to demonstrate synthesis of metal oxides using plasma based methods where much of the work is focussed using atmospheric pressure based microplasmas technique. Also the objectives are to study metal oxide properties through plasma process and manipulating its electronic structure by identifying various defects and quantum confinement effect. Finally, applicability of some the synthesized metal oxides were successfully integrated into photovoltaic devices where direct material integrity directly from the process was carried out. Also, biomedical application of metal oxide were explored.
The most highlighting feature of the thesis is demonstration of metal oxide nanoparticle synthesis using two different techniques, plasma induced non-equilibrium electrochemistry (PiNE) and gas phase microplasmas. The spotlight of these techniques were shown with use of simple precursors for synthesis. A highly stable colloidal Cu-oxide quantum dots (QDs) size ranging from 2 – 4 nm were shown using PiNE technique for different process currents, where a detailed study showing formation mechanism of QDs were performed. Further the technique is extended to synthesis of other metal oxide especially manganese oxide. Finally, a generalised PiNE method applicable to synthesis 3d transition metal oxides were concluded. In gas phase microplasmas, synthesis of nanoscale zinc oxide tetrapods (ZnO nTPs) structure was demonstrated along with wide range of size and shaped nanoparticles (NPs) depending on the process parameters. Phase and structural stability of the QDs and nTPs were also studied for different annealing temperatures. An in-depth material characterisation of all these metal oxides were carried out that reveals various defects in the material found to influenced by the experimental conditions. Finally, metal oxide (CuO QDs/ZnO) solar cell devices and with perovskite material are fabricated. These devices are the first step towards cost-effective and advance metal oxide device fabrication.

Date of Award	Mar 2020
Original language	English
Sponsors	Department for the Economy
Supervisor	Paul Maguire (Supervisor) & Davide Mariotti (Supervisor)