Formation of II-VI nanocrystals in polymeric matrix: Thermolytic synthesis and structural characterization

In this work we report on the growth of US and ZnS semiconductor nanocrystals embedded in a polymeric matrix (polystyrene) by synthesizing a metal thiolate precursor and its subsequent thermolysis at about 300 degrees C after dispersion in the polymer. The crystallinity, shape and size of the metal sulfide nanocrystals were investigated by x-ray diffraction and transmission electron microscopy. The microstructural. analysis demonstrates that our synthesis procedure allows us to control the nanocrystal growth in order to form nanoparticles with diameter as small as circle divide=2nm. In particular, XRD analysis reveals that only US and ZnS nanocrystals of zincblende structure are formed. TEM images show that the metal sulfide nanocrystals are monocrystals of spherical shape and the size dispersion is < 20%. Our experiments indicate that the nanocrystal capping agent is performed by the sulfur atoms at the surface of the nanoparticle bound to alkyl chain of the thiolate. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.