Control of Kinetics and Thermodynamics in Microwave-Assisted Synthesis of Nanocrystals

This dissertation describes the methodology for using microwave chemistry to control the reaction kinetics and/or thermodynamics of semiconductor nanocrystalline materials. The introduction provides a background of synthetic methods for semiconductor quantum dots evolved from using micelles to highly reactive precursors and finally to high temperature injection and microwave chemistry to produce the maximum number of nucleation events. Therefore, the control over the dispersity and size of the materials to allow semiconductor nanocrystals to be grown has led to a vast amount of research and experimentation for modeling the best reaction in the most efficient method of formation. The production of the best quality materials is driven through selectively isolating the precursors that actively contribute to the most nucleation events followed by efficient growth of the nanomaterials through the use of microwave chemistry (Chapter 2). Using microwave chemistry, the formation of CdS quantum dots of high quality and tight dispersity is achieved using TOPS as the sulfur source which has not been achieved previously (Chapter 3). The application of classical nucleation theory to microwave chemistry is further explored to determine how the Ostwald ripening phenomenon applies to the different growth mechanisms in the synthetic methodology to explore the idea of re-nucleation (Chapter 4). This synthetic method can also be utilized to explore multiple crystal structures that are produced by simple manipulation of the precursor solution and are fully characterized using absorption, emission, powder X-ray diffractometry (XRD), and transmission electron microscopy (TEM) (Chapter 5).