Fluorescence properties of rhodamine B-doped SiO 2–TiO 2 films prepared by sol–gel process

Abstract

The sol–gel coating processes of the rhodamine B-doped SiO 2–TiO 2 system, and the influence of the compositions of the SiO 2–TiO 2 system on the fluorescence properties of rhodamine B-doped films have been investigated. The main absorption band of rhodamine B-doped films can be attributed to the rhodamine B monomers, and only a very weak absorption band of the dimer can be observed. The relationship between absorbance and film thickness was linear for the rhodamine B-doped SiO 2–TiO 2 films. The single emission band in fluorescence spectrum of rhodamine B-doped films can be attributed to transitions from the lowest-lying level of the first excited electronic state to the electronic ground state of rhodamine B monomers. The fluorescence intensities of rhodamine B-doped SiO 2–TiO 2 films obviously increased with the increase of film thickness. The relationship between fluorescence intensity and film thickness was also linear for the rhodamine B-doped SiO 2–TiO 2 films. The compositions have significant influence on the fluorescence intensities of the rhodamine B-doped SiO 2–TiO 2 films. The fluorescence intensities decreased obviously with increase of TiO 2 when the content of TiO 2 was more than 30%.