Cubic mesoporous frameworks with a mixed semiconductor nanocrystalline wall structure and enhanced sensitivity to visible light.

Since the discovery of mesostructured materials in the early 1990s a great deal of effort has been devoted to developing new structures, compositions, and functionalities. The ability to synthesize semiconducting singleor multicomponent metal-oxide mesostructured materials with controlled morphologies has been a major step towards functional materials with potential applications in sensing, catalysis, and optoelectronics. We describe herein the synthesis and properties of a new generation of ordered mesostructured composites with mesopore walls composed of integrated 3D arrays of different types of wide and narrow band-gap semiconductor nanocrystals including oxides, sulfides, and selenides. Such an integrated 3D coassembly of different functional units is of great importance for optoelectronic applications that rely on the transfer of electrons or holes between two or more active components. Examples of such systems are sensitized titania solar cells and photocatalysts, for which it has been shown that solar conversion efficiency can be strongly increased in the presence of sensitizing dye molecules or narrow band-gap semiconductor nanocrystals. Fabrication techniques previously developed for such functionalized composite titania materials are based on step-bystep methods in which organic molecules or premade semi-