ZnS:Mn nanoparticles conjugated to sol-gel-derived silica matrices

Composites from ZnS:Mn nanoparticles and modified silicas are of interest for a broad range of potential applications in the form of films, structured particles, and self-assembled structures (e.g., colloidal crystals). They combine the versatility of silica sol gel chemistry with the wealth of functionalities available from doped nanoparticulate semiconductors (e.g., optical, electrical, and magnetic). In this work, ZnS:Mn nanoparticles have been prepared and modified in such a way that they can be incorporated seamlessly, either by inclusion or by covalent bonding into silicas. Functionalization was achieved through the use of silanes or thioles. Further processing by standard sol gel chemistry then either led directly to covalent conjugation with the silica network formed after condensation, or to isolated particles encapsulated in a silica shell. The results are heavily loaded (up to 30 wt%), transparent (including semiconductor particles that are smaller than 15 nm) and luminescent films, and massive bodies. In this work, the progress of nanocomposite formation was followed mainly by luminescence spectroscopy. Further work will have to address the electrical and magnetic properties of these nanocomposites as well.