Mechanistic insights into structure-property relationships of doped metal oxide nanocrystals produced from a continuous growth synthesis
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Date
2019-04-30
Authors
Crockett, Brandon
Journal Title
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Publisher
University of Oregon
Abstract
Colloidal metal oxide nanocrystals have tremendous potential to solve some of the world’s biggest problems in energy storage and harvesting, medicine, catalysis, electronics, and information technology. Colloidal metal oxide nanocrystals display unique size- and structure-dependent properties that differ from the bulk materials. The incorporation and utilization of these nanomaterials into modern technology hinges upon chemists’ abilities to synthesize the nanomaterials with atomic-level precision and control over size, morphology, composition, and surface chemistry. To this end, advances in synthetic development hold the keys to providing high-performance nanomaterials to solve global problems.
This dissertation focuses on new synthetic approaches to producing doped-metal oxide nanocrystals, using a continuous growth synthesis. The synthesis allows for nanocrystals to be grown layer-by-layer at nearly the atomic level, much akin to atomic layer deposition in solid state chemistry and living polymerizations in polymer chemistry. This layer-by-layer growth allows for metal oxide nanocrystals to be synthesized with angstrom-level control over size, composition, and distribution of dopant atoms. This level of structural control has produced significant advancements in the investigations of structure/property relationships. With In2O3 as a model system, in this dissertation nanocrystals are shown to exhibit composition-dependent optical properties, size-dependent electrical properties, and dopant distribution-dependent plasmonic properties.
This dissertation begins with a brief introduction outlining current challenges chemists face in synthesizing metal oxide nanocrystals. The advances in continuous growth synthesis developed in the Hutchison laboratory are then discussed. Additionally, the technological relevance of In2O3 (the focus material of this dissertation) is highlighted. The following chapters demonstrate new investigations only made possible through the continuous growth synthesis. First, improvements in nanocrystal composition is demonstrated, through the doping of In2O3 nanocrystals with a variety of transition metal dopant atoms, and the dopant atom incorporations are shown to be stoichiometric, and the dopants are homogenously distributed. Next, nanometer-level control over Sn-doped In2O3 is demonstrated, in order to relate thin film resistivity to nanocrystal diameter. Finally, control over radial distribution of dopants is demonstrated in Sn-doped In2O3 and highlights the striking influence the dopant distributions exhibit on the plasmonic properties of the nanocrystals.
This dissertation contains previously published and unpublished co-authored material.