Xavier Roy

Xavier Roy

Research Interest

Summary

Our research is focused on the design and synthesis of atomically-defined inorganic building blocks that can be assembled into functional electronic and magnetic materials. We study the chemical and physical principles that govern the organization of molecular clusters into nanostructured materials and the emergence of collective physical properties that arise in these assemblies.

Conventional solid-state compounds are infinite, crystalline arrays of densely packed and strongly interacting atoms. The properties of the individual atoms dictate the interatomic interactions that are the basis for thermal, electrical and magnetic collective properties of advanced materials. While the Periodic Table is rich, it nonetheless contains only a limited number of elements. We synthesize nanoscale analogs of atoms (large molecular clusters) and assemble these artificial atoms into atomically-precise solids. Since we build our own ‘atoms’, we can fully tune their size, composition, electronic and magnetic properties. We control their assembly by adjusting the type, number and placement of the ligands that we append to the surface of the clusters. In effect we are encoding desirable physical properties in the building blocks and controlling their interactions in the solid-state. Once synthesized, we investigate the structural characteristics and the electronic, optical, thermal and magnetic properties of these solid-state compounds. We aim to design materials with multiple functionalities and emerging electronic and magnetic properties. We are particularly interested in compounds on the edge of stability, by definition solids that undergo a phase transition through the application of an external stimulus (for example, light, pressure, or magnetic or electric field).

We are also involved in a number of other projects. These include 1) developing synthetic approaches to assemble molecular clusters into precise and predictable nanostructures such as nanowires, monolayers and mesoporous materials; and 2) synthesizing luminescent and magnetic molecular cluster probes for the visualization of neurotransmitter release.

Students in our group are exposed to a broad range of topics and techniques, including chemical synthesis, structural and physical property characterization and device fabrication.

B. Choi, K. Lee, A. Voevodin, J. Wang, M. L. Steigerwald, P. Batail, X.-Y. Zhu, X. Roy, “Two-Dimensional Hierarchical Semiconductor with Addressable Surfaces,” J. Am. Chem. Soc. 2018140, 9369-9373.

E. A. Doud, M. S. Inkpen, G. Lovat, E. Montes, D. W. Paley, M. L. Steigerwald, H. Vazquez, L. Venkataraman, X. Roy, “In Situ Formation of N-Heterocyclic Carbene-Bound Single-Molecule Junctions,” J. Am. Chem. Soc. 2018140, 8944-8949.

A. Voevodin, L. M. Campos, X. Roy, “Multifunctional Vesicles from a Self-Assembled Cluster-Containing Block Copolymer,” J. Am. Chem. Soc. 2018140, 5607-5611.

A. Pinkard, A. Champsaur, X. Roy, “Molecular Clusters: Nanoscale Building Blocks for Solid-State Chemistry,” Acc. Chem. Res. 201851, 919-929.

Q. Li, J. C. Russell, T.-Y. Luo, X. Roy, N. L. Rossi, R. Jin, “Modulating the Hierarchical Fibrous Assembly of Au Nanoparticles with Atomic Precision,” Nature Commun. 20189, 3871.

X. Zhong, K. Lee, B. Choi, D. Meggiolaro, F. Liu, C. Nuckolls, A. N. Pasupathy, F. De Angelis, P. Batail, X. Roy, and X.-Y. Zhu, “Superatomic Two-Dimensional Semiconductor,” Nano Lett. 201818, 1483-1488.

Y. Zang, A. Pinkard, Z.-F. Liu, J. B. Neaton, M. L. Steigerwald, X. Roy, and L. Venkataraman, “Electronically Transparent Au–N Bonds for Molecular Junctions,” J. Am. Chem. Soc. 2017139, 14845-14848.

E. S. O’Brien, M. T. Trinh, R. L. Kann, J. Chen, G. A. Elbaz, A. Masurkar, T. L. Atallah, M. V. Paley, N. Patel, D. W. Paley, I. Kymissis, A. C. Crowther, A. J. Millis, D. R. Reichman, X.Y. Zhu, X. Roy, “Single-crystal-to-single-crystal intercalation of a low-bandgap superatomic crystal,” Nature Chem. 20179, 1170-1174.

W.-L. Ong, E. S. O’Brien, P. S. M. Dougherty, D. W. Paley, C. F. Higgs III, A. J. H. McGaughey, J. A. Malen, X. Roy,”Orientational order controls crystalline and amorphous thermal transport in superatomic crystals,” Nature Mater. 2017, 16, 83-88.

G. A. Elbaz, W.-L. Ong, E. A. Doud, P. Kim, D. W. Paley, X. Roy, J. A. Malen, “Phonon Speed, Not Scattering, Differentiates Thermal Transport in Lead Halide Perovskites,” Nano Lett. 201717, 5734-5739.

G. Lovat, B. Choi, D. W. Paley, M. L. Steigerwald, L. Venkataraman, X. Roy, “Room-Temperature Current Blockade in Atomically Defined Single-Cluster Junctions,” Nature Nanotechnol. 201712, 1050-1054.

Y. Zang, A. Pinkard, Z.-F. Liu, J. B. Neaton, M. L. Steigerwald, X. Roy, L. Venkataraman, “Electronically Transparent AuN Bonds for Molecular Junctions,” J. Am. Chem. Soc. 2017 139 14845-14848.

E. S. O’Brien, M. T. Trinh, R. L. Kann, J. Chen, G. A. Elbaz, A. Masurkar, T. L. Atallah, M. V. Paley, N. Patel, D. W. Paley, I. Kymissis, A. C. Crowther, A. J. Millis, D. R. Reichman, X.Y. Zhu, X. Roy, “Single-Crystal-to-Single-Crystal Intercalation of a Low-Bandgap Superatomic Crystal,” Nature Chem. 20179, 1170-1174.

W.-L. Ong, E. O’Brien, P. S. M. Dougherty, D. W. Paley, C. F. Higgs III, A. J. H. McGaughey, J. A. Malen, X. Roy, “Orientational Order Controls Crystalline and Amorphous Thermal Transport in Superatomic Crystals,” Nature Mater. 201716, 83-88.

G. E. Elbaz, D. Strauss, O. E. Semonin, T. D. Hull, D. W. Paley, J. S. Owen, C. Kagan, X. Roy, “Unbalanced Hole and Electron Diffusion in Lead Bromide Perovskites,” Nano Lett. 201717, 1727-1732.

G. E. Elbaz, W.-L. Ong, E. A. Doud, P. Kim, D. W. Paley, X. Roy, J. A. Malen, “Phonon Speed, Not Scattering, Differentiate Thermal Transport in Lead Halide Perovskites,” Nano Lett. 201717, 5734-5739.

B. Choi, J. Yu, D. W. Paley, M. T. Trinh, M. V. Paley, J. M. Karch, A. C. Crowther, C.-H. Lee, R. A. Lalancette, X. Zhu, P. Kim, M. L. Steigerwald, C. Nuckolls, X. Roy, “van der Waals Solids from Self-Assembled Nanoscale Building Blocks,” Nano Lett. 201616, 1445-1449.

A. Turkiewicz, D. W. Paley, T. Besara, G. Elbaz, A. Pinkard, T. Siegrist, X. Roy, “Assembling Hierarchical Cluster Solids with Atomic Precision,” J. Am. Chem. Soc. 2014136, 15873-15876.

C.-H. Lee, L. Liu, A. Turkiewicz, C. Bejger, T. Goko, C. Arguello, B. Frandsen, S. Cheung, T. Medina, T. J. S. Munsie, R. d’Ortenzio, G. M. Luke, T. Besara, R. A. Lalancette, T. Siegrist, P. W. Stephens, A. C. Crowther, L. E. Brus, Y. Matsuo, E. Nakamura, Y. J. Uemura, P. Kim, C. Nuckolls, M. L. Steigerwald, X. Roy, “Ferromagnetic ordering in superatomic solids,” J. Am. Chem. Soc. 2014136, 16926-16931.

X. Roy, C.-H. Lee, A. C. Crowther, C. L. Schenck, T. Besara, R. A. Lalancette, T. Siegrist, P. W. Stephens, L. E. Brus, P. Kim, M. L Steigerwald, C. Nuckolls, “Nanoscale Atoms in Solid-State Chemistry,” Science 2013341, 157-160.