Dr. Tobias Hanrath, Cornell University
Seminar Abstract:
Controlling the composition and structure of materials at the nanometer scale provides unprecedented opportunities to create novel materials with properties by design. In particular, nanostructured materials offer an ideal experimental platform to evaluate structure/property relationships in quantum-confined systems that could ultimately provide technological value. Recent advances in synthesis, characterization, and the emerging understanding of their size-dependent properties have created exciting prospects for semiconductor nanomaterials to contribute to the development of next-generation energy conversion technologies. Semiconductor nanocrystal quantum dots are particularly attractive material candidates for the efficient capture of solar emission in inexpensive, thin film photovoltaic devices by virtue of their large absorption cross sections, low-cost solution-phase processing and size-tunable energy gaps. We review our recent work investigating the exciton dissociation and charge transport between quantum confined nanocrystals as a function of the interparticle spacing. Beyond controlling the interdot spacing, directing the nanocrystals into ordered superstructures with predefined translational and orientational order is a critical parameter for controlling the electronic coupling in three-dimensional superlattices. We will present recent experiments relating superlattice symmetry and optical properties of the ensemble.