Aggregated Structure and Electrical Properties of Composite L-B Film Containing Cyanine Dyes Regulated by Bilayer-Forming Amphiphiles

We have found that cyanine dye molecules were adsorbed to the monolayer of dialkylammonium amphiphiles at air-water interface. Both monolayers and multilayers of the composite films were made on glass substrates by Langmuir-Blodgett technique. Spectral studies for the composite monolayer showed that J-like aggregates of the dye molecules were formed at the early stage of the adsorption process of the dye. The structure of hydrophilic portions of a monolayer as well as the coulombic interaction between dye molecules and the monolayer were found to dominate the adsorption process of cyanine dye. X-ray diffraction indicated that the dye molecules aggregated between hydrophilic groups of the composite multiayer. Measurements of polarized absorption spectra for the composite multilayer showed that dye molecules were parellel to the substrate. The photocurrent spectrum of the composite multilayer corresponds closely to the absorption spectrum. This indicates that carrier generation in the photoconduction arises from the dye aggregates.