Fabrication and Characterization of Self-Assembled Nanoparticle/Polyelectrolyte Multilayer Films

The formation of multilayer films of organothiol-stabilized gold nanoparticles and polyelectrolyte, synthesized using the "layer-by-layer" technique, has been investigated. The formation of such films requires the alternation of surface charge with each layer deposited and is thus amenable to study by the Kelvin probe technique. The early stages of multilayer film formation have been studied using a combination of X-ray photoelectron spectroscopy, spectroscopic ellipsometry, and Kelvin probe microscopy. Our results suggest that the polyelectrolyte/nanoparticle film can be considered as a wide-band-gap semiconductor with a depletion width, at the substrate/film interface, extending several nanometers into the film. From our ellipsometry data, we are able to provide optical constants for these hybrid organic/inorganic films.