Easily processable composite films consisting of a non-ionic surfactant, Pluronic P123, as the organic component, and silica as the inorganic component have been fabricated. These films served as the host matrices for various squarylium- and xanthene-type organic dyes. Picosecond time-resolved luminescent studies revealed that the excited state lifetimes of the squarylium dyes increased when compared to those measured in solution. The xanthene dyes' lifetimes, on the other hand showed a moderate decrease upon being incorporated into the solid matrix. In the case of the squarylium dyes, addition of antimony doped tin oxide nanoparticles led to either an increase or decrease in the lifetimes, depending on the structure and charge of the dye. Also, substantial decreases in excited state lifetimes are observed with the addition of well known organic quenchers: methyl viologen, p-nitroaniline, or bromophenol blue. The high quenching efficiencies observed indicate that the dyes and the quenchers form complexes from both being sequestered within the micro-environment of the micelles formed by the surfactant. The excellent photostability and ultrafast ground state recovery of the intercalated dye complexes make these composite films ideally suited for use as the active component in an optical switching device.
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