Systems and methods for forming uniform monolayers of nanoparticles

A method preparing a uniform nanoparticle coating on a substrate, comprising the steps of:

• a) providing a nanoparticle solution comprising an initial concentration of nanoparticles in a solvent, the solvent having a solvent vapor pressure and a solvent surface tension;
• b) containing a sub-phase solution of a denser, immiscible liquid within a vessel at a sub-phase surface tension, density and viscosity, the vessel contained within a controlled environment;
• c) depositing a volume of the nanoparticle solution onto a top surface of the sub-phase solution, the volume of the nanoparticle solution being unconstrained by walls of the vessel, wherein nanoparticle solution spreading at a nanoparticle solution spreading rate and solvent evaporating at a solvent evaporation rate controls the formation of a nanoparticle film;
• d) evaluating the nanoparticle film for non-uniform features;
• e) repeating steps a)-d) when non-uniform features are observed, such that a ratio of the nanoparticle solution spreading rate to solvent evaporation rate is altered in step c) and the nanoparticles form a uniform nanoparticle monolayer on the sub-phase solution;
• and
• f) contacting the substrate with the nanoparticle monolayer such that the substrate is coated with a uniform nanoparticle coating.