Center for Functional Nanomaterials Seminar

Semiconducting, insulating, and metallic nanoparticles have attracted considerable interest recently due to their size-dependent, quantum confinement characteristics, which make them attractive for a broad platform of optical, magnetic, and electronic devices. Proposed commercial applications include solid state lighting devices, magnetic recording media, ultra-light video displays, and bio-imaging reagents.

For nanoparticles to be employed in an array of commercial and industrial applications, a technique for the facile, rapid, and site-selective assembly of homogeneous, densely packed, defect-free thin films must be realized. The most widely used methods for casting nanoparticle (NP) constituents into densely packed, thermally stable films, such as evaporation-driven self assembly and Langmuir-Blodgett casting, have some recognized limitations, including the inability to achieve both large-scale ordering of the nanoparticles as well as robust chemical and structural properties. NP deposition schemes also require an understanding of both the NP dynamics in solution and the interactions that govern nanoparticle-substrate and nanoparticle-nanoparticle binding. Further, these procedures require knowledge of the intrinsic and collective properties of NPs that arise from of electrostatic, magnetic, and fluctuating electric dipole effects. The organization and stability of colloidal NP assemblies are markedly affected by the surface charge state of the constituents. Although much research has been done on the assembly of nanoparticles with a distribution of surface charge states, little has been done on the assembly of like-charged nanoparticles. In this case, repulsive Coulomb interactions, as well as van der Waals, dipole-dipole, and steric interactions govern the types of assemblies that can form. Recent progress in the electrophoretic deposition of nanoparticles and other nanoscale materials will be the emphasis of this presentation.