dc.contributor.author Zhang, Heyou dc.date.accessioned 2022-01-12T01:15:28Z dc.date.available 2022-01-12T01:15:28Z dc.date.issued 2021 dc.identifier.uri http://hdl.handle.net/11343/295915 dc.description © 2021 Heyou Zhang dc.description.abstract Nanocrystals are a remarkable class of materials, which exhibit size-dependent optical and electronic properties. Numerous applications have been proposed for these materials but they suffer from a key handicap. Nanocrystals are generally made in solution, rendering integration into devices very challenging. Therefore, there is an increasing demand for new fabrication methods to transfer nanocrystals from solution to a solid-state substrate. In this thesis, we develop a new, direct assembly method based on electrophoretic deposition (EPD), which we call Surface Templated Electrophoretic Deposition (STEPD). Our research starts by demonstrating the successful assembly of single gold nanocrystal arrays. The strength of the applied electric field and the electrolyte concentration are key parameters that control the assembly process. The orientation of asymmetric gold nanorods can also be controlled by carefully designing the template. With further experimental and theoretical investigation, we find that the electrically induced dipole moment on asymmetric nanorods plays a major role in orientating the nanorod during EPD assembly. Our STEPD method is not only able to assemble gold nanorods in designed orientation horizontally but also able to assemble gold nanorods vertically with respect to the substrate. The universality of STEPD is also demonstrated by the successful assembly of gold nanocrystals with different sizes and shapes, magnetic Fe$_3$O$_4$ nanocrystals, fluorescent organic nanoparticles and semiconductor quantum dots with different photoluminescence. During our investigation, we find that there is a minimum particle size limit in STEPD. Very small nanocrystals (i.e. < 20 nm in size) are difficult to assemble via EPD due to their smaller total charge and stronger Brownian motion. Finally, we propose three potential applications derived from STEPD assembled arrays including hydrogen gas sensing, single particle addressing and anti-reflective metasurfaces. Through this thesis, we believe the direct STEPD assembly method holds great potential as an efficient and versatile assembly method for large-area, single nanocrystal arrays. dc.rights Terms and Conditions: Copyright in works deposited in Minerva Access is retained by the copyright owner. The work may not be altered without permission from the copyright owner. Readers may only download, print and save electronic copies of whole works for their own personal non-commercial use. Any use that exceeds these limits requires permission from the copyright owner. Attribution is essential when quoting or paraphrasing from these works. dc.subject direct assembly, dc.subject nanocrystals, dc.subject nanoparticles, dc.subject single nanocrystal array, dc.subject universal assembly method, dc.subject electrophoretic deposition, dc.subject large scale assembly, dc.subject arbitrary nanounit fabrication, dc.subject electrophoresis, dc.subject nanofabrication dc.title Direct Assembly of Single Nanocrystal Arrays dc.type PhD thesis melbourne.affiliation.department School of Chemistry melbourne.affiliation.faculty Science melbourne.thesis.supervisorname Paul Mulvaney melbourne.contributor.author Zhang, Heyou melbourne.thesis.supervisorothername Ann Roberts melbourne.tes.fieldofresearch1 340603 Colloid and surface chemistry melbourne.accessrights Open Access
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