Abstract
One embodiment of the present invention provides a method for forming a nanoparticle film, which comprises the steps of: preparing a nanoparticle solution, which comprises a solvent and supersaturated nanoparticles with surface ligand molecules; and dip coating a substrate to the nanoparticle solutions to form a first monolayer of the nanoparticles on the substrate, the first monolayer and repeatedly formed monolayers on top of the first monolayer constructing the nanoparticle film. Another embodiment of the present invention provides a nanoparticle film, comprising a first monolayer consisted of a two-dimensional nanoparticles array that are near-field coupled with each other to have tunable plasmonic properties by changing the number of stacked monolayers.