Center for Functional Nanomaterials Seminar

The ability to synthesize quantum dots of desired size, shape, and chemical composition provides a rich family of nanoscale building blocks for the assembly of new solid thin films and devices. Self-assembly of different classes of these "artificial atoms" with distinct electronic, magnetic, and optical properties into composite solids provides access to new classes of multi-functional materials with fascinating and novel behavior. In this talk I will discuss the modular design of one class of binary nanocomposite (the PbTe/Ag2Te system) for potential thermoelectric applications. The development of synthetic routes to size-tunable PbTe and Ag2Te nanocrystals, along with their assembly into single-component solid thin films and nanocrystal transistors will be discussed. Subsequently, the self-assembly of these components into binary nanocrystal superlattices and multicomponent thin films will be presented. Investigations of the electronic and thermal properties of these PbTe/Ag2Te binary nanocrystal composites, which represent the first studies of the collective physical properties of this new class of materials, have revealed exciting behavior. The electronic transport studies demonstrate synergism amongst the components which leads to a 100-fold enhancement in the p-type conductance over either individual nanocrystal building block. Studies of the thermal properties of these films have uncovered 5-10 fold reductions in thermal conductivity in comparison to the corresponding bulk crystals, which is promising for the development of thermoelectrics and materials for thermal management.