Ultra-Large-Area Self-Assembled Monolayers of Nanoparticles

Large-area self-assembled monolayers of nanoparticles are fabricated on the surface of deionized water by controlled evaporation of nanoparticles dispersed in a binary solvent mixture. The difference in solvent volatility and partial coverage of the trough leads to a flux of nanoparticles toward the evaporation front. The monolayers are comprised of monodisperse magnetite and gold nanoparticles or slightly more polydisperse manganese oxide nanoparticles. The floating monolayers are transferred onto different substrates by the Langmuir-Schaefer method. Surfactants in the colloidal solution and substrate materials have significant impact on the monolayer formation. Bilayers of nanoparticles with different twist angles between layers are also obtained by double deposition.