Synthesis, Assembly And Characterization Of Metal Sulfide Semiconductor Nanocrystals

Sulfide is a class of important semiconductors which could be applied tophotovoltaics cells, optoelectronic devices, biological labeling, etc. Current researchof sulfide nanomaterials mainly focuses on the simple-structured orsingle-compositional nanocrystals. However, the sulfide nanomaterials with multiplecomponents are different from traditional semiconductor nanomaterials, the novelenergy band structure of which is promising in improving their properties. Withdevelopment of nanoscience and nanotechnology, research on multicompositional orhybrid semiconductor has attracted increasing attention. In this dissertation,dodecanethiol-based mixture system has been designed to synthesize multicomponentsulfide nanocrystals. Meanwhile, investigation on growth mechanism, self-assemblyand optical property of obtained nanocrystals have been systematically carried out.In the dodecanethiol-based mixture system, dodecanethiols act as sulfur source,solvent and capping agent. It could react with metal salts to produce metal thiolates atroom temperature, which could decompose to corresponding sulfide nanocrystals athigh temperature. However, for proper control ablity towards the desired nanocrystals,surfactants other than dodecanethiol should be added to provide differentcoordination. Thiol-oleylamine and thiol-oleic acid system have been successfullydeveloped to synthesize wurtzite CuInS2and Cu2ZnSnS4nanocrystals with uniformcomposition and size. Moreover, these two systems behave different coordinateability in producing nanocrystals with unlike morphologies. This method requiressimple reagents and operation, having potential in large-scale production.On the other hand, thiol-oleic acid system could be used to synthesizeheterostructured nanorods. By adding the prepared Cu2S or Ag2S nanocrystals asseeds, uniform ZnS nanorods have been successfully obtained. Cu2S and Ag2Snanocrystals play as both the nuclei and the catalysts in boosting the growth of ZnSone-dimensional growth.Success in our experiments proves the advantage of dodecanethiol-based mixture system. Except from simplity, controllability and generality, our system hassuperiority in synthesizing multicomponent sulfide nanocrystals, which is helpful forfurther theorical study and practical application of multicomponent semiconductornanomaterials.