Monodisperse Carbon Nanotubes and Metal Nanoparticles: Centrifugal Sorting and Device Implications

Single-walled carbon nanotubes (SWNTs) and noble metal nanoparticles (NPs) are central to numerous research efforts in fields such as electronics, plasmonics, and catalysis due to their unique optical and electronic properties. Because small changes in the structure of these nanomaterials have dramatic impacts on their properties, there is strong motivation to overcome the inherent polydispersity in as-synthesized populations in order to achieve uniformity across an ensemble for potential applications. In this dissertation, centrifugal sorting methods are presented for improving the monodispersity of both SWNTs and metal NPs, and the resulting improvement when used in applications is discussed.;Multiple iterations of density gradient ultracentrifugation (DGU) are presented for isolation of SWNTs by diameter and electronic type concurrently, yielding extraordinarily sharp optical transitions for monodisperse metallic samples in solution and film form. Electronic properties of resulting transparent thin films are found to be decoupled from optical properties across the observed diameter range. DGU-sorted SWNTs are then used in film form to systematically study the effect of electronic type when used as the transparent anode in organic photovoltaic devices. Device efficiencies are shown to be fifty times greater when monodisperse metallic SWNT films are used compared to their semiconducting counterparts, which subsequent characterization shows to be primarily due to lower sheet resistances of metallic SWNT films and their relative insensitivity to doping effects.;Sedimentation-based density gradient centrifugation (DGC) methods are then presented for sorting gold nanoparticles (AuNPs) by both aggregation state and shape. Plasmonic nanoantennas consisting of gold core/silica shell nanoparticles that host SERS reporter molecules at the gold/silica interface are sorted by aggregation state, and a dramatic increase in resulting ensemble SERS intensity is demonstrated for populations with minimized monomer content. DGC is then extended to sorting unencapsulated faceted AuNPs by shape using an atomic plane-selective surfactant, where non-faceted byproducts are successfully removed and a degree of shape sorting within polyhedral AuNPs is observed. Sorted populations are then used as seed particles for semiconducting nanowire growth, providing a significant growth rate enhancement. These results demonstrate both the versatility of centrifugal nanomaterials sorting and the distinct advantages afforded for future applications.