Cadmium selenide quantum dot doping of organic-inorganic hybrid materials derived by sol-gel processing.

Nano-sized, phenyl-capped CdSe quantum dots were isolated, after preparation inside reversed micelles present in AOT/H2O/heptane, and then successfully redispersed in the amino-silicate ormosil (i.e. organically modified silicate) derived from 3-aminopropyl-(trimethoxy)silane. Doped ormosils were formed into films of a few mu m thickness or small bulk samples. The ormosils were structurally characterised by means of absorption spectroscopy in the visible and near-infrared ranges, and by Si-29 solid state nuclear magnetic resonance spectroscopy. The siloxane matrix of the amino-silicate ormosil was found to be 84% condensed and polymeric water molecules are hydrogen bonded into the matrix, presumably at silanol and amine sites. CdSe dots of apparently good monodispersity and radius 1.5 to 2.4nm (going from yellow to red in visual appearance) were redispersed in the amino-silicate ormosil. Attempts to prepare larger dots resulted in flocculation of the CdSe. The maximum loading of CdSe dots in the amino-silicate matrix was measured to be 2.05 weight% CdSe0.72, where the density of the amino-silicate host was around 0.5 to 0.7 of the density of a typical, melt-derived silicate glass.