Date of Graduation
Doctor of Philosophy in Chemistry (PhD)
Chemistry & Biochemistry
Second Committee Member
Third Committee Member
Pure sciences; Applied sciences; Cadmium sulfide; Nanocrystals; Quantam disks; Quantam dots
The bottom-up colloidal synthesis opened up the possibility of finely tuning and tailoring the semiconductor nanocrystals. Numerous recipes were developed for the preparation of colloidal semiconductor nanocrystals, especially the traditional quantum dots. However, due to the lack of thorough understanding to those systems, the synthesis chemistry is still on the empirical level. CdS quantum dots synthesis in non-coordinating solvent were taken as a model system to investigate its molecular mechanism and formation process, ODE was identified as the reducing agent for the preparation of CdS nanocrystals, non-injection and low-temperature synthesis methods developed. In this model system, we not only proved it's possible to systematically study the formation procedure of semiconductor nanocrystals, the insight learned during the research but also enhanced our understanding to this delicate system and promoted the development of synthetic chemistry. Although quantum dots could be routinely prepared in the lab with mature recipes, the colloidal semiconductor quantum well type materials are still hard to fathom. CdSe quantum disks structure was thoroughly analyzed with polar axes as the growth direction along the thickness direction, with both basal planes ended with Cd atom layer, which was coordinated with carboxylate ligands. Besides, four different thickness CdS quantum disks were prepared, its size-dependent lattice dilation, extremely sharp band-edge emission, and two-order of magnitude faster photoluminescence decay compared to quantum dots was investigated.
Li, Zheng, "Semiconductor Nanocrystals: From Quantum Dots to Quantum Disks" (2012). Theses and Dissertations. 424.