Surafce Modifcation Of Hydrophobic Quantum Dots And Their Applications

Due to the prominent properties of quantum dots(QDs), preparation methods of high quality QDs has been fastly developed in the past decades. Therefore, various QDs with high quantum efficiencies QDs have been synthesize by organ-solution method. In order to find their better applications, the surface of hydrophobic QDs need to be modified for more stability and functionality. This thesis addressed on the suface modification of the hydrophobic QDs by silane coupling agent, the dispersion the modified QDs into the silica-based matrix, and the study on the application of these prepared materials. The work consists four parts mainly as follows:(1) Surface modification of hydrophobic quantum dots using silane coupling agentsThe surfaces of hydrophobic CdSe/CdZnS quantum dots(OA-capping QDs) were modified by using TEOS, APS, MPS, respectively. Adjusting concentration of the silane coupling agent, reaction time and other conditions during the surface modification, we can efficiently improve the fluorescence quenching problem of QDs. The modified QDs remained the original optical properties and high fluorescence when they were used for therafter application procedures.(2) Preparation and characterization of fluorescent composite filmsHighly luminescent composite films with –[Si O2-QDs]- stratified-structure are prepared by Layer-by-Layer self-assembly method using the Cd Se/Cd Zn S QDs surface-modified by TEOS and MPS. The QDs dispersed uniformly in the film with concentration up to 2.62×10-12 mol/cm2. The prepared composite multilayer films have good transparency and thermal endurance properties.(3) Preparation and characterization of fluorescent gel glassThe modified QDs are dispersed successfully in a silica-gel to abtain the Si O2-QDs glass. Then, the transparent Si O2-QDs gel glasses with high fluorescence are obtained. The quantum efficiencies of gel glass QDs modified with APS have a great difference for QDs with different crystal structures. The prepared Si O2-QDs gel glasses also have high quantum efficiency, uniform dispersion of QDs, good transparency and thermal endurance properties.(4) Preparation of silica fluorescent nanoparticles containing multiple QDsBased on surface modification of hydrophobic QDs using TEOS, we have embedded multiple modified QDs into the silica nanoparticles by a modified “St?ber” mothed. The quantum efficiency of the prepared nanoparticles incorporating red-emitting QDs reached to 31%.