Candidate
Leon Mintz
Title
Molybdenum Disulphide (MoS2) Nanosheet Inks Evaluated for Printed Electronics and Application to Thin-Film Transistors
Supervisor
William Wong
Abstract
Scalable fabrication of large-area devices requires harnessing an agile, sophisticated and versatile deposition method with a high performance materials system. Inkjet printing is a versatile deposition technique that has been used for the fabrication of electronic circuits, from simple conductive tracks to complete 3D logic circuits. The ability to deposit a large range of materials offers researchers high flexibility in device optimization and process design. The emergence of solution-processable 2D layered materials pushes the performance boundaries of printed devices. The use of 2D functional materials combined with the growing knowledge in the field of inkjet printing processing has great potential for competing with traditional fabrication methods in terms of performance and cost.
In this research, a significant first step was taken in studying the behaviour of MoS2 nanosheet suspensions through the modification of the physical properties of the suspension and the surface energy of target substrates for improved printability and film formation. For the first time, it was shown that the ring-stain effect can be directly exploited for the fabrication of circular devices using inkjet printing. Minimal suspension concentration was evaluated for the first time by a continuum percolation simulation using real particle size distribution. Stability of MoS2 nanosheets under thermal treatment was studied for the first time and decomposition temperature was determined. It was shown that thick films exhibit bulk conductivity but no field-effect was observed. Finally, spray coating was demonstrated as a potential alternative deposition method to inkjet printing, as it is capable of depositing extremely thin.