This dissertation describes the relationship between the surface chemistry of colloidal semiconductor nanocrystals (quantum dots, QDs) and their optoelectronic properties, such as photoluminescence and degree of quantum confinement. We primarily focus our efforts on one particular subset of ligands known to couple strongly to the inorganic core of the QD to decrease its quantum confinement, phenyldithiocarbamates (PTCs). We focus first on the development of quantitative Nuclear Magnetic Resonance (NMR) techniques to characterize the identity and quantity of ligands (such as PTCs and oleic acid) bound to nanocrystal surfaces. When we correlate the surface chemistry information obtained from NMR with the optical spectra of our QDs, we find that for strongly-delocalizing ligands like PTC, the spatial distribution of ligands on the QD surface affects the overall degree of delocalization. In the later chapters of this thesis, we describe two avenues for exploiting the relationship between surface coverage of exciton-delocalizing ligands and quantum confinement to design strongly coupled, hierarchical nanomaterials for efficient charge transport in films or in solution. We explore the treatment of thin lead sulfide QD films with a PTC derivative to improve their overall conductivity relative to benzoic acid, a similar molecule that does not affect confinement. Finally, we describe a potential strategy to improve the yield and rate of hole transfer to a tethered phthalocyanine molecule using dithiocarbamate and thiolate linkers

Last modified

• 04/26/2018

Creator

• Rachel Dory Harris

DOI

• https://doi.org/10.21985/N28D85

Subject

• Chemistry

Keyword

• exciton delocalization
• nuclear magnetic resonance
• quantum dot
• ligand-ligand coupling
• dithiocabamate

Date created

• 2017-01-01

Resource type

• Dissertation

Rights statement

• In Copyright