Dissertation Defense: Sophia Click, Chemistry
Sophia M. Click, Chemistry
*under the direction of Dr. Sandra Rosenthal
“Unraveling the Effects of Morphology at the Core/shell Interface of InP-based Quantum Dots”
03.10.23 | 1:30pm CST | Stevenson 4327 | Zoom
Indium phosphide quantum dots (QDs) are semiconductor nanocrystals who’s tunable photophysical properties makes them useful as emitters in a wide array of applications, including solid state lighting, lasing, bioimaging, and photonic quantum technology, without the inherent toxicity concern of cadmium-based emitters. Growing thick shells of a wider-band gap semiconductor, such as ZnSe or ZnS, over InP QDs increases their photostability and brightness by passivating undercoordinated surface atoms that quench photoluminescence and provides a robust chemical protection from the environment. Unfortunately, the zinc chemistry has proven difficult to control, resulting in uneven shell morphology and incomplete core passivation that limits photostability. Since photostability is dictated by the bonding at the core/shell interface, improving the photostability of InP-based QDs will require an intricate understanding of the core/shell interface. In order to precisely tailor photophysical properties for industrial implementation, there is a need for fundamental investigations relating morphology of the core/shell interface with its impact on photoluminescent behavior. In this work, the impact of interfacial alloying in thick-shell InP/ZnSe QDs on PL behavior has been assessed at the ensemble and single particle level to reveal the complexity of exciton dynamics in this system. In both cases, the techniques for analyzing shell morphology fall woefully short in comparison to the arsenal of photoluminescent analysis techniques. As such, a semi-automated tool for quantitatively assessing biological particle morphology has been adapted for nanocrystals. This tool provides powerful analytics to discern the impact of key shelling parameters on both the core/shell interface and shell morphology. The insights from this advanced characterization tool have far-reaching implications for QD technology and could propel the development of InP-based QDs with precisely tuned photoluminescent behavior.