Langmuir-Blodgett fabrication of two-dimensional robust cross-linked nanoparticle assemblies

Two-dimensional nanoparticle cross-linked networks were constructed by using the Langmuir-Blodgett technique, where neighboring particles were chemically bridged by bifunctional linkers at the air/water interface. The cross-linking process was effected at high surface pressures by ligand intercalation and surface exchange reactions between the bifunctional linkers (rigid aryl dithiols) and the particle-bound alkanethiolates, resulting in the formation of long-range ordered and robust particle superlattice networks. Even for particles with varied thicknesses of the protecting monolayers, effective cross-linking was achieved where the interparticle spacing appeared to be determined by the molecular length of the bifunctional linkers. One of the potential applications of the resulting particle networks is for the construction of two-dimensional quantum dot arrays by ultraviolet and ozone molecular cleaning, where the organic components were removed rather efficiently leaving the metal particles deposited onto the substrate surface. This could be used for efficient large-scale surface nanofabrication in a nonlithographic manner.