Active hybrid materials by nanoscale chemistry

We present different arrangments of hybrid nano-objects for optical applications: Highly concentrated luminescent colloids (II-VI quantum dots, YVO4:Ln) are prepared and stabilized through the grafting of organic molecules at their surface. These nanocrystals can further be used for the synthesis of well defined nanomaterials. For instance, highly luminescent transparent films for integrated optics are obtained by using YVO4:Ln nanocrystal- silica composites. 3D-random networks of quantum dots are prepared by gelation of colloids. As in the silica system, the transparent percolating structure can be described as homogeneous assemblies of fractal clusters whose sizes are inferior to visible-range wavelength. 3D ordered arrays of quantum dots are prepared by a confined growth of nanocrystals in mesoporous silica films. Using these templates, the 3D ordering of nanoparticles can be extended at a large scale on different substrates. These high density arrangments of nanocrystals are required in different applications such as nonlinear optics or semiconductor lasers.