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On-Surface Characterization of Atomically Precise Graphene Nanoribbons: Variations in Structure, Substrate, and Deposition Method
Graphene-based materials have been the focus of intense research in recent years, and owing to the desirable properties they possess, the variety of potential applications for them is likewise impressive. Chapter 1 discusses graphene nanoribbons (GNRs) and how their precise atomic features exhibit critical influence over electronic characteristics such as band gaps, magnetic edge states, and topological phases. One can therefore engage in design of molecular precursors to build atomically precise GNRs from the bottom up with desired features which can be probed with surface science techniques. These elements include ribbon width, edge geometry, heteroatomic doping, and many more. In this dissertation are results of scanning probe microscopy experiments to examine structural and electronic characteristics of several GNR structures derived from surface-assisted synthesis techniques. First, we studied the growth of chevron GNRs on Cu(111) (Chapter 2). Epitaxial growth of chevron polymers and GNRs at low temperatures arose out of the strong interactions between structure and surface. In Chapter 3 we discuss the development of an alternative deposition technique, direct contact transfer (DCT). It arose as an analogue of dry contact transfer for solution-synthesized GNRs. The procedure was demonstrated for two precursors, and the intermediates observed in the process of annealing were determined by DFT to be stabilized by π-π interactions. Chapter 4 covers the on-surface synthesis of laterally extended chevron GNRs (eGNRs). By slight modification of the chevron precursor structure, the band gap of the GNRs was reduced in accordance with established theory. In Chapter 5 results are presented on the on-surface synthesis of intrinsically porous chevron-derived GNRs. These GNRs featured electronic states at their pores as well as reduced band gaps relative to chevron GNRs. Chapter 6 details work on the growth of GNRs from a precursor with two centers of rotation and the potential for influencing its self-assembly. Finally, Chapter 7 contains a summary of the work performed as well as directions to be explored in the future as relate to this project.
Chemistry|Electrical engineering|Molecular chemistry|Atomic physics|Molecular physics
Teeter, Jacob D, "On-Surface Characterization of Atomically Precise Graphene Nanoribbons: Variations in Structure, Substrate, and Deposition Method" (2020). ETD collection for University of Nebraska - Lincoln. AAI28259278.