Date of Award

5-2015

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Chemistry

Advisor

Robert W. Meulenberg

Second Committee Member

Scott D. Collins

Third Committee Member

Karl D. Bishop

Abstract

Understanding the role that surface chemistry plays in modifying the optical properties of quantum dots (QDs) has been an active field of research for some time now. Recently, one of the goals of many research groups involve possessing systematic control of the ligand exchange process which can provide the ability to tailor the surface with a specific amount of surface ligand, thereby having unparalleled control over the optical properties. In this presentation, we will discuss our efforts towards investigating controlled efforts of ligand exchange in CdSe QDs. Most notably, we focus on the stearic acid/trioctylphosphine oxide (TOPO) coated CdSe system with efforts towards isolation of nanocrystals. Using a combination of nuclear magnetic resonance and infrared spectroscopy and thermogravimetric analysis, we probe the extent of ligand composition as function of consequent purifications.

We also discuss the effects of ligand exchange on the QDs after the cleaning process QD materials that still possess quantum confinement like features, yet are not dispersible in typical organic solvents. Titrations of ligands onto the highly cleaned materials lead to dispersed QDs and recovery of quantum yield. During the course of these measurements, we will discuss the impact these surface chemistry treatments have on the photoluminescence of these materials.

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