Our research focuses on the chemistry, physics and material science of inorganic nanostructures. By combining expertise in colloidal synthesis, self-assembly, and characterization of nanomaterial properties, our group creates novel materials for electronic, photovoltaic, thermoelectric, and catalytic applications.
Colloidal synthesis of functional inorganic nanostructures has developed into a new branch of synthetic chemistry. Starting with preparations of simple objects like spherical nanoparticles, the field is now moving toward more and more sophisticated structures where composition, size, shape, and connectivity of multiple parts of a multicomponent structure can be tailored in an independent and predictable manner.
Inspired by the way most solids form in nature, with individual atoms or molecules assembling themselves into rigid, highly uniform arrays, we study assembly of monodisperse nanocrystals into ordered superstructures. Assembling nanoscale functional building blocks provides a powerful modular approach to the design of novel materials and ‘metamaterials’ with programmable physical and chemical properties.
Bringing together compounds of intrinsically different functionality constitutes a particularly powerful route to creating novel functional materials with synergetic properties found in neither of the constituents. Binary nanoparticle superlattices (BNSL) self-assembled from different combinations of semiconductor, magnetic, metallic and dielectric nanocrystals show amazing structural diversity. The range of materials which can be used as building blocks in BNSL structures seems to be limited only by our ability to make a particular material in form of monodisperse nanoparticles. Self-assembly of functional nanoparticles into single- and multicomponent superlattices offers nearly endless possibilities for creating novel materials for a range of applications from photovoltaic and thermoelectric devices to non-linear optics, multiferroics, and multicomponent catalysts. However, we have very limited understanding of the processes which govern BNSL formation and determine stability of different structures. We investigate the fundamental aspects of self-assembly in the nano world.
Nanocrystal superlattices constitute a novel type of condensed matter whose properties originate both from the properties of individual nanocrystals and the collective phenomena caused by the crosstalk of the superlattice building blocks. We study electronic properties (carrier mobility, doping, charge transport mechanism, photoconductivity, thermopower) and heat transport in single- and multicomponent nanocrystal solids. The knowledge obtained from fundamental studies of nanocrystal assemblies will be used for development of practical solution-processed devices utilizing nanocrystals and nanocrystal assemblies. The performance of solution-processed nanocrystal transistors and solar cells compares favorably with competing technologies. The nanocrystal field effect transistors allow reversible switching between n- and p-transport, providing options for printable complementary metal oxide semiconductor (CMOS) circuits and p-n junctions.
