A Facile Route to ZnO Nanoparticle Superlattices: Synthesis, Functionalization, and Self-Assembly

Highly ordered, free-standing, complex, two- or three-dimensional (2D or 3D) nanoparticle superlattice arrays were created by either evaporation-induced self-assembly or precipitation-induced self-assembly from the size-monodispersed ZnO nanoparticles functionalized by carboxylic and alkylthiol ligands. The synthesis of the constituent ZnO nanoparticles is both novel and facile and is suggested as a generic means of producing oxide nanomaterials by reaction of metal cations and oxide anions in alcohol solutions at room temperature. The regularity of the nanoparticle products and their chemical functionalization provides the means to achieve superlattice thin films on indium tin oxide (ITO)-coated glass slides. Low-angle XRD, SEM, and TEM confirm the formation of these highly organized, 2D or 3D self-assembled superlattices that adopt an unusual primitive cubic structure. The properties of the nanoparticles and the superlattices are also described in the paper.