Photoluminescence from organic–inorganic multilayers based on sol–gel derived titania

Transparent films of laser dye doped titania, thinner than 0.1 μm, were spin-coated from sols obtained at room-temperature from titanium tetraisopropoxide. Spectrophotometric measurements performed on the films revealed that the incorporation into the inorganic network does not affect the optical properties of the dye molecules, although the emission intensity was low, owing to the small thickness. To obtain stronger luminescence intensity avoiding the formation of cracks and defects, multilayers composed of alternated doped titania and polymethyl methacrylate thin films, were developed. Due to the refractive index contrast between the inorganic and the organic layers, the grazing-angle emission collected from the multilayers edges was found to be enhanced and considerably narrower than the single layer luminescence.