Methods of synthesis of colloidal nanoparticles

• Main Author: Gerbec, Jeffrey A
• Format: Dissertation
• Language: English
• Subjects: chemistry, inorganic
• ISBN: 0542571676; 9780542571671

Colloidal semiconductor nanocrystals, with unique size-dependent optical properties, have great promise for integration into next generation technologies including solid-state lighting and biological labeling. A general method of reproducible, large scale and environmentally safe synthetic preparation becomes crucial for integration in commercial devices. In addition to the synthetic protocol, an understanding of the surfaces of the as prepared material is critical for obtaining a high quantum yield that is stable for long periods of time in ambient conditions. In this dissertation, a new synthetic approach to general colloidal nanocrystals is presented. Microwave heating of molecular precursors increases the rate of reaction from days to minutes for a host of nanomaterials. The most relevant for the study of inorganic phosphors is CdSe and InP and their respective ternary analogs. Post synthetic surface treatment of the as prepared material show a tremendous increase in the QY for as prepared InP and InGaP. Post synthetic surface treatment is carried out by photoactivated etching with dilute HF. In the case of InGaP, the QY reaches 0.80 from 0.05 in a matter of minutes. Other surface treatment strategies that address the stability is carried out by forming epitaxial core shell structures. It is shown that using ZnS as a wide band gap shelling material, the QY of InP reaches 0.42 in solution and is stable for months. These are significant steps toward the engineering of semiconductor quantum dot phosphors for solid state lighting and biological labeling.