Fluorescence properties of hybridized thin films consisting of organic dye J-aggregates and titanium oxide nanoparticles

Abstract

Aiming at a highly bright emitter, hybridized thin films consisting of organic dye TDBC J-aggregates (JA) and titanium oxide (TO) nanoparticles (NPs) have been fabricated successfully. The fluorescence intensity and the corresponding fluorescence quantum yield multiplied ca. 10 times and ca. twice, respectively. TO NPs have a high refractive index, and have no absorption loss like metal NPs. On the other hand, extinction (absorption) and fluorescence spectra are in general overlapped in organic dye JA, that is, so a small Stokes’ shift. Namely, the present phenomenon could be qualitatively explained by the simultaneously optical processes of both “excitation enhancement” induced directly by near-field effect from TO NPs and “emission enhancement” as a radiation of scattering field from TO NPs, which were polarized by the excitation energy from TDBC JA to TO NPs. In other words, the definite scattering peak in the extinction spectrum of TO NPs should be tuned efficiently with extinction (absorption) and fluorescence peak bands of TDBC JA.