Surface Functionalization Of Semiconductor Nanoparticles And Their Composite In Polymer Matrix

Semiconductor nanoparticles possess many unique optical properties, high surface-to-volume ratio and other properties related to their nanometer dimension. Their optical properties can be easily tailored not only by changing the particle size, but also by suitable ions doping, structure fabrication and surface modification. Especially, the functionalized nanoparticles with special functionality and selectivity can easily interact with the polymer monomers or biomolecules. So these functional nanoparticles and their nanocomposites have large potential applications in the fields of biology, electronic and optoelectronic devices as well as photovoltaic cells.In this thesis, we selected the phenanthroline and 8-Hydroxyquinoline derivatives as the ligands to functionalize the surface of CdS and ZnS semiconductor nanoparticles via ligand exchange process. Our aim is to endow with them excellent fluorescence properties. It was found that the size of the functionalized nanoparticles with the above ligands did not change before and after modification. However, the photoluminescence properties had obvious change, in particular, the fluorescence intensity evident enhanced. The functionalized ZnS nanoparticles with 8-Hydroxyquinoline derivatives exhibited the highly photoluminescence quantum yields (QYs) up to 49 %. These results indicated that the fluorescent metal complex formed on the surface of the nanoparticles from the functional ligand and the surface metal ions of nanoparticles may have a cooperating interaction with the inherent emission of nanoparticles, which influenced the optical properties of the resulting composite nanoparticles. In addition, to realize the function and to impart these fluorescent nanoparticles with excellent processability, a series of transparent luminescent bulk nanocomposites were prepared by in situ bulk polymerization in the presence of nanoparticles. The results indicated that after the nanoparticles were introduced into the polymer matrix, the excitation and emission peak positions of the nanoparticles had obvious shift, in particular, these properties also exhibited a dependence on the nanoparticles concentration in polymer matrix. At the same time, we also studied the effect of polymer matrix with different functional side groups on the optical properties of the resultant nanocomposites, and the possible mechanism was also discussed. These functional nanoparticles and their polymer nanocomposites can be potentially used to design and fabricate novel photoelectric devices.