Lanthanide doped hybrid organic-inorganic nanocomposites

Sol-gel matrices have been investigated for some years as potential matrices for rare earth luminescence. The design of sol-gel matrices inside which the hydroxyl content can be minimized or/and inside which the rare earth is protected via complexation or encapsulation is desirable to avoid the RE3+ luminescence quenching. We have investigated the Nd3+ Sm3+, Dy3+, Er3+ and Tm3+ optical properties in siloxane-zirconium hybrid matrices prepared at room temperature. In these hydrophobic matrices, RE3+ fluorescence is always observed but lifetimes and quantum yields are strongly dependent on the synthetic procedure. By using the reducing power of the hydridosilanes precursors, it is also possible to prepare hybrid materials with cations in different valence states. The in situ formation of hydrogen, provided by the cleavage of the Si-H bonds during hydrolysis and condensation reactions, reduces the europium and cerium in Eu2+ and Ce3+ leading to a broad visible emission. In addition to this emission, a blue emission of the sol-gel matrices under UV excitation is also observed.