Luminescence properties of nanophosphors: metal ion-doped sol-gel silica glasses

Photoluminescence of xerogel and sol-gel SiO2 glasses doped with metal ions, metal complexes and semiconductor nanocrystals are investigated at 300 K and 10 K to clarify the optical properties and the electronic structures of nanophosphors. Sol-gel glasses doped with 3d, 4d and 5d transition metal ions exhibit a bright luminescence with various colours due to the (LMCT)-L-3 transition associated with closed-shell molecular complex centres. Luminescence from rare earth( III) complexes doped in the same matrix serve as a sensitive probe to determine axial and chiral complex structures. Luminescence properties are investigated of doped semiconductors ZnS: Cu, Al dispersed as nanocrystalline green phosphors in xerogel with various lifetime components. The sol-gel silica-based phosphors are characterized by unusual valence states of the transition metal ions, stable centres in organic-inorganic hybrid hosts and the 500 ps lifetimes of D-A pairs due to spd hybridization effects in semiconductor nanocrystals.