Author

Kira D. Patty

Date of Award

2015

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Optical Science and Engineering

Committee Chair

Seyed M. Sadeghi

Committee Member

Don A. Gregory

Committee Member

Joseph Geary

Committee Member

Lingze Duan

Committee Member

Abdalla Elsamadicy

Subject(s)

Quantum dots., Semiconductor nanocrystals.

Abstract

Quantum dots (QDs) are semiconductor nanocrystals that self-assemble from solution and come in a variety of shapes, sizes, and materials. Due to their extremely small sizes, QDs exhibit atom-like quantum mechanical properties that make them highly desirable for many applications and for fundamental research in quantum mechanics. Further, when continuously irradiated, the intensity of QD emissions can increase over time; a phenomenon referred to as photo-induced fluorescence enhancement (PFE). For almost every application that deals with the optics of QDs, the enhancement of their quantum efficiency and control of their photoluminescence properties is highly desirable. This research explores how the presence of a metal oxide can alter the photoluminescence of CdSe-based colloidal QDs. The results show that certain QDs can become dramatically brighter when a metal oxide is present and this brightening occurs at the single QD level. Further, the results demonstrate that different metal oxides can interact uniquely with different types of QD structures. These effects were analyzed in terms of the photo-induced processes that drive PFE within the QDs and how those processes can be altered by the photo-catalytic properties of the metal oxides. In particular, this research shows that a metal oxide can act to stabilize the fluorescence of certain QDs over time even under conditions that generally lead to a reduction in the QDs' brightness. These results are unprecedented in the literature and represent a critical first step toward developing new techniques to tailor the photoluminescence of colloidal QDs.

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