Photoluminescent particle surfaces in mesoporous hosts

• Applicant: Professorin Dr. Nicola Hüsing
• Co-Applicant: Professor Dr. Oliver Diwald
• Subject Area: Physical Chemistry of Solids and Surfaces, Material Characterisation ; Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
• Term: from 2009 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 131357714

Alkaline earth oxide (AEO) nanocrystals show a so far unnoticed potential for applications as inorganic phosphors with adsorption-dependent optical properties. To connect these nanoscopic objects to our macroscopic world under preservation of their interface-related optical properties, new approaches for nanoparticle immobilization inside mesoporous host matrices need to be developed. The goal of the present project is to create nanoscale AEO particles (MgO, CaO, BaO, SrO) in a controlled way inside inert as well as chemically reactive mesoporous coatings (SiO2, TiO2, mixed TiO2/SiO2 or MgO) using novel metal vapour infiltration techniques. The influence of the coating properties thickness, porosity, pore size distribution and pore connectivity on the deposition of AEO particle and consequently their optical properties will be investigated. The generation of multiple AEO particle concentration gradients within one mesoporous coating will be achieved by spatially controlled functionalization of sites for AE metal nucleation, e.g. by utilizing surface groups with variable thermal stabilities, or by patterning of the coating with lithographic or focused ion beam techniques. In addition, multiple coating steps will allow for structures with gradients in porosity and chemical composition, which will also be employed for the generation of AEO concentration gradients. On the basis of defined coating thicknesses of the host and spatially adjustable concentrations of various AEO particle types we envision composites where the deliberate photoexitation of one selected area inside the coating can produce photoluminescence emission in the second region based on energy transfer processes. As an alternative synthetic approach, we will employ the controlled adsorption of silanes onto AEO particle surfaces in combination with subsequent oxidative conversion steps to generate dense silica layers for their chemical protection. Respective products can then be directly incorporated into the evaporation-induced self-assembly process for the formation of the mesoporous coatings.

• DFG Programme: Research Grants
• International Connection: Austria