Luminescent properties of organic-inorganic hybrid monoliths containing rare-earth complexes

Transparent organic-inorganic hybrid monoliths containing rare-earth complexes (Eu(TTA)3Phen, Tb(Sal)3) were prepared via the sol-gel technique. It could be observed by transmission electron microscopy that the fluorescent particles are distributed in the matrix at the microscopic level. The matrix is composed of organic-inorganic semi-interpenetrating networks, i.e., PHEMA-SiO2 system. The fluorescence emission spectra of samples are similar to those from corresponding powdered Eu(III) and Tb(III) complexes, and the half-widths of the strongest bands are less than 10 nm, which indicates that the monolith exhibits high fluorescence intensity and color purity. Furthermore, the fluorescence spectra exhibit no obvious change with decreasing nanoparticle size of the rare-earth complex. The fluorescence lifetimes of samples are longer than pure Eu(III), Tb(III) complexes, respectively. Samples irradiated with an UV lamp (365 nm) are still transparent but become bright red and green in color due to fluorescence of Eu(III) and Tb(III) complexes.