WHITE PHOSPHORS FROM A SILICATE-CARBOXYLATE SOL-GEL PRECURSOR THAT LACK METAL ACTIVATOR IONS

Highly emissive (with an external quantum yield exceeding 35 percent a t a 365-nanometer excitation wavelength) broadband phosphors can be sy nthesized from a tetraalkoxysilane sol-gel precursor and a variety of organic carboxylic acids. The air-stable phosphors were synthesized at low temperatures (less than 300 degrees C) and displayed broad visibl e photoluminescence spectra that appeared white to the eye. Water-solu ble phosphors can be prepared by the substitution of 3-aminopropyltrie thoxysilane for tetraalkoxysilane in the synthesis. These materials ar e the most efficient extrinsic phosphors that do not contain activator metal ions.