IRG III

Rational Design of Nanoparticle and Molecule-Based Functional Materials

Faculty Coordinators:  S. Sibener, D. Talapin

Sustained progress by many groups, including ours, has enabled the preparation of a variety of materials with metallic, insulating, semiconducting, magnetic and catalytic properties in the form of nanometer-scale crystals with precisely tailored size, shape and composition. What is not yet understood is the full methodology of how to assemble these nanoscale building blocks into two- and three- dimensional arrays that have a desired structure and functionality. The goals of this IRG are ambitious and have the potential to transform materials design in this area. We wish to develop a complete “systems approach”to nanoscale materials design and organization, taking into consideration individual nanoparticle and molecular properties and the interactions within both single and multicomponent particle ensembles. Further, we seek to understand how inter-particle molecular spacers, covalent linkers, and substrate platforms can be manipulated in concert to achieve the desired physical or chemical function.

The study of the dynamics of nanoparticle self-assembly is still in its infancy and major questions need to be addressed to realize our goals. For example, it is not yet clear how the delicate interplay between electrostatic and chemical interactions governs structure formation on the nanoscale. In principle, these interactions can be tuned by changing nanoparticle cores, encapsulating ligands, and molecular linkers. More broadly, we can ask to what extent is self-assembly governed by energy minimization considerations and to what extent are they driven by far-from-equilibrium dynamics Answering these questions could lead to new methodologies that allow multicomponent nanoparticle building blocks to produce an as-of-yet unrealized diversity of materials with functions optimized for particular applications.

This IRG addresses two critical issues. The first deals with discovering the fundamental aspects responsible for self-organizing array assembly including creation of single and multi-component systems, functional molecular linkers and assembly dynamics. Building upon results obtained in those studies, we will then seek to create new functional nanomaterials.

We have assembled the expertise to implement our vision for nanoscale materials assembly. This includes nanomaterials synthesis and characterization (Guyot-Sionnest, Irvine, Shevchenko, Talapin, Tian), molecular synthesis (Hopkins, Yu), UHV and electro-chemical STM/AFM (Sibener), ultrafast spectroscopy (Engel), nanostructure assembly (Irvine, Jaeger), and theory (Witten). 

Summary:
This IRG plans to develop the tools to create a new class of materials. The shear abundance of different, currently-available, nanometer-scale building blocks, each with distinctive properties, portends a revolution in the design of new materials with specialized functions. However, in order to harness this potential, we must learn to assemble these entities controllably into two- and three-dimensional materials. We have already shown that an astonishing variety of structures can be assembled. Yet, the principles by which these systems form are unknown and clearly go far beyond the simple ideas of space-filling packing. The critical goals outlined above include understanding the fundamental aspects of nano-particle self-organization and the systematic tuning of array properties. Our ambitious, interdisciplinary research program seeks to create a unified approach to nanoscale-materials assembly that would produce paradigms for a new generation of functional materials with real-world applications.