The electrical properties of metal-molecular nanoparticle networks are studied both theoretically and experimentally. Benzenedithiol-aluminum cluster linear chains, Y-shaped and H-shaped networks are modeled with semi-empirical methods to study the electronic properties of such structures. The HOMO (highest occupied molecular orbital)-LUMO (lowest unoccupied molecular orbital) gaps of the benzenedithiol-Al cluster networks decrease several eV compared to the isolated benzenedithiol molecule. Frontier energy levels become more closely spaced as the size of the molecular networks increase, accompanied with an increased HOMO energy and decreased LUMO energy, indicating a decreased energy barrier to electron transport. Delocalized spatial distribution of the frontier orbitals indicates a high probability for electron transmission and corresponds well with peaks near the HOMO-LUMO gap in the electronic density of states.
Self-assembled molecular networks consisting of dithiol/thiol molecules and 30 nm colloidal gold nanoparticles are fabricated with a solution-based method. Electrical measurements performed on these nanostructures show a typically linear current-voltage characteristic while nonlinear I-V curves are also observed for networks built of benzenedithiol or hexane/octanethiol molecules. Further analysis with atomic force microscopy shows that the network’s conductance is determined by the molecule’s conductivity and network dimensions. Circuit model consisting of networked molecular resistors is applied to study the interconnections between the particles within the network and the simulated values of the network’s conductance is consistent with the measured values.
Theoretical and experimental study on the electrical properties of metal-molecular nanoparticle networks reveals the influence of molecules and metallic particles on determining the network’s conductivity. Such self-assembled networks can be used to implement several circuit elements, such as resistors, diodes, etc., and more complicated computation components such as nanocells, memristors, etc. The electrical properties of the networks can be tuned by proper choice of molecules, metallic particles and network geometry making them promising for future molecular electronic circuits. / Graduate
| Identifer | oai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/7526 |
| Date | 02 September 2016 |
| Creators | Zhang, Po |
| Contributors | Papadopoulos, Chris, Papadopoulos, Christo |
| Source Sets | University of Victoria |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Rights | Available to the World Wide Web |
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