Layer-by-layer ionic self-assembly of Au colloids into multilayer thin-films with bulk metal conductivity

Colloidal Au nanoparticles, each encapsulated by polyelectrolytes, have been self-assembled into multilayer films in a layer-by-layer fashion. Atomic force microscopy (AFM) demonstrates that close-packed, three-dimensional arrays with uniform roughness have been achieved. Organic interconnects (alternating cationic and anionic monolayers) covalently and electrostatically linked adjacent metal nanoparticles and formed uniform tunnel junctions. Electrical conductance measurements reveal that a resistivity of 5×10−6 Ω cm for 15 layers of 5 nm Au colloid films, the same order of magnitude of that of bulk gold metals, has been achieved for the first time.