ORGANIC DYE-DOPED SILICA FILMS BY THE LIQUID-PHASE DEPOSITION METHOD AS POTENTIAL NEW HYBRID MATERIALS FOR PHOTONICS

Silica films doped with malachite green (MG) or uranine (UR) were depo sited on the surface of a glass slide at 35 degrees C from saturated h ydrofluorosilicic acid solution containing these dyes. The steady fluo rescence of MG was observed in silica films, which was absent in aqueo us solutions. The fluorescence lifetime of MG in silica films was abou t 60 times longer than that in aqueous solutions. No absorption change s of MG-doped silica films by the LPD method were observed after stori ng 24 h in 25% ammonia solution, while those prepared by the sol-gel m ethod showed changes immediately after immersion. The absorption and f luorescence spectra varied slowly by the heat treatment and by the imm ersion in hydrochloric solutions, indicating the deprotonation and pro tonation of MG. The delayed fluorescence of UR was observed in silica films. All these results indicated organic dyes were fixed rigidly in silica films prepared by the present LPD method.