Enhancement effect of photoluminescence in assemblies of nano-ZnO particles/silica aerogels

${\mathrm{SiO}}_{\mathrm{2}}$ aerogels were prepared by a sol-gel method and supercritical drying. Introduction of nano-ZnO into nanopores of the ${\mathrm{SiO}}_{\mathrm{2}}$ aerogels is performed by immersion, chemical reaction, and hydrolysis. Photoluminescence of these assemblies of nano-ZnO particles/${\mathrm{SiO}}_{\mathrm{2}}$ aerogels were systematically measured. For each assembly, a very strong photoluminescence (PL) band with the peak position of about 500 nm was observed. The luminescence intensities of the assemblies of nano-ZnO particles/${\mathrm{SiO}}_{\mathrm{2}}$ aerogels are 10–50 times higher than that of nanostructured ZnO bulks. The quantum efficiency of the PL band for the assemblies is in the range of 0.2%–1%. This luminescence enhancement effect is caused by the increase of the singly ionized oxygen vacancies in nano-ZnO particles, which are located in nanopores of the ${\mathrm{SiO}}_{\mathrm{2}}$ aerogel.