Tunable photoluminescence in monodisperse silica spheres

The nanometer-scale luminescent monodisperse silica spheres have been prepared by a water/oil (W/O) microemulsion method and the size of these spheres changed with the different concentrations of 3-aminopropyltriethoxysilane (APTES). The luminescent monodisperse silica spheres at the submicrometer scale have been prepared via Stöber method and the particles size increased with the increase of the amino concentrations. After calcination, all silica spheres do not change obviously in size. The annealed silica spheres contain C impurities and O defects, which resulted in the luminescence of silica spheres. The spheres showed variations in emission due to the different size and the concentration of organosiloxane precursors. Therefore, the emission can be tuned finely via the change of organosiloxane precursor and the size of samples.