Synthesis And Modification Of Water-Soluble Luminescent Quantum Dots

Quantum dots (also known as colloidal semiconductor nanocrytals, QDs) are generally composed of II-VI and III-V elements, which exhibit strongly size dependent optical and electrical properties. Highly quality semiconductor nanocrystals have shown potential applications in thin film light-emitting devices, non-linear optical devices, solar cells and life science. Quantum dots synthesized by organometallic approach have high quantum yield, sharp emission spectra, monodispersity and good crystallinity. However, key chemicals used in this route are toxic, expensive, pyrophoric, and even explosive. In this thesis, we used microwave irradiation method to synthesize a series quantum dots in aqueous solution by using thiols as the stabilizers. This method is simple and controllable; as-prepared quantum dots show good optical properties. The main contributions are as follows:1. A kind of alloyed QDs with CdSe core and gradient CdSeS external shell was rapidly synthesized in aqueous phase by microwave irradiation with controllable temperature in one hour. In synthetic procedure, microwave irradiation was used to desulfur 3-mercaptopropionic acid, and the released S participated the growth of CdSe and naturally form an alloy CdSeS shell on the surface of the CdSe seeds that formed in initial heating stage. The as-prepared QDs presented good optical properties, their QYs were up to 25 % and FWHM of the emission spectrum peak was about 28 nm.