A nanoparticle multilayer thin film is provided in which nanoparticles which are not electrically insulated from each other are spaced apart from one another at a reduced distance. The nanoparticle multilayer film includes: at least one first nanoparticle layer including first nanoparticles that are surface-modified with a cationic metal-chalcogenide compound; and at least one second nanoparticle layer including second nanoparticles that are surface-modified with an anionic metal-chalcogenide compound, wherein the first nanoparticle layer and the second nanoparticle layer are alternately stacked upon one another.

An optical element that features high transmission and low reflectivity at infrared wavelengths is described. The optical element includes a substrate, an adhesion layer on the substrate, and an anti-reflection coating. Substrates include chalcogenide glasses, InAs, and GaAs. Adhesion layers include Se, ZnSe, Ga.sub.2Se.sub.3, Bi.sub.2Se.sub.3, In.sub.2Se.sub.3, ZnS, Ga.sub.2S.sub.3 and In.sub.2S.sub.3. Anti-reflection coatings include one or more layers of DLC (diamond-like carbon), ZnS, ZnSe, Ge, Si, HfO.sub.2, Bi.sub.2O.sub.3, GdF.sub.3, YbF.sub.3, In.sub.2Se.sub.3, and YF.sub.3. The optical elements show high durability and good adhesion when subjected to thermal shocks, temperature cycling, abrasion, and humidity.