This thesis explores electron transport across single-molecule circuits via a combination of theory and experiment.
Chapter 1 begins by introducing the diverse motivations for studying single-molecule electronics within engineering, chemistry and physics. Key aspects of the theory of electron transport across single-molecule circuits are summarized, before describing the modified scanning tunneling microscope technique used to measure single-molecule circuits.
Chapter 2 presents a new theoretical approach to calculating quantum interference, which allows interference effects to be easily visualized within a matrix. The approach demonstrates that interference is vital to molecular-scale transport and accounts for conductance decay with length across molecular wires.
In Chapter 3, a novel chemical design strategy is used to exploit destructive quantum interference in a series of long molecular wires containing a central benzothiadiaole unit. Scanning tunneling microscope-break junction measurements show the wires exhibit extremely nonlinear current-voltage characteristics, and the conductance of a six-nanometer molecule can be modulated by a factor of 10,000.
Chapter 4 details how the scanning tunneling microscope setup may be modified to incorporate electrochemical impedance spectroscopy. Impedance measurements are then used to interrogate the solvent environment and measure capacitance. Chapter 5 demonstrates solvent-induced shifts in molecular conductance can be correlated with changes in junction capacitance. Together, the chapters in this thesis provide a framework for using chemical design to develop single-molecule circuits with functional properties.
| Identifer | oai:union.ndltd.org:columbia.edu/oai:academiccommons.columbia.edu:10.7916/eqts-8j83 |
| Date | January 2022 |
| Creators | Greenwald, Julia E. |
| Source Sets | Columbia University |
| Language | English |
| Detected Language | English |
| Type | Theses |
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