Energy and Charge Migration in Nanoscale Materials

Molecular and nanoscale electronics are exceptionally versatile materials due to ability to tune their electronic properties by changing chemical functionalization or molecular size and shape. Due to their small, dynamics that occur at surfaces and interfaces within these materials often have a disproportionate influence over their properties. The Roberts group seeks to understand how interfacial interactions impact the electronic properties of these materials.

While members of our group work on an array of chemical problems, the theme that runs through each is that we develop new ways of utilizing time-resolved nonlinear spectroscopy to separate dynamics that occur in different areas of the materials we study. Projects currently underway in the group include developing techniques that can selectively examine dynamics at buried interfaces in thin film electronics. We also utilize time-resolved Raman spectroscopy to look at ligand-nanocrystal interactions.

M. S. Azzaro, A. K. Le, H. Wang, & S. T. Roberts, "Ligand-Enhanced Energy Transport in Nanocrystal Solids Viewed with Two-Dimensional Electronic Spectroscopy" J. Phys. Chem. Lett., (2019), DOI:10.1021/acs.jpclett.9b02040.

J. A. Bender, E. K. Raulerson, X. Li, T. Goldzak, P. Xia, T. Van Voorhis, M. L. Tang, & S. T. Roberts, "Surface States Mediate Triplet Energy Transfer in Nanocrystal-Acene Composite Systems" J. Am. Chem. Soc., 140, 7543-53, (2018).

M. S. Azzaro, A. Dodin, D. Y. Zhang, A. P. Willard, & S. T. Roberts, "Exciton-Delocalizing Ligands Can Speed Up Energy Migration in Nanocrystal Solids" Nano Letters, 18, 3259-70, (2018).

A. K. Le, J. A. Bender, D. H. Arias, D. E. Cotton, J. C. Johnson, & S. T. Roberts, "Singlet Fission Involves an Interplay Between Energetic Driving Force and Electronic Coupling in Perylenediimide Films" J. Am. Chem. Soc. 140, 814-16, (2018).

R. E. McAnally, J. A. Bender, L. Estergreen, R. Haiges, S. E. Bradforth, J. M. Dawlaty, S. T. Roberts, & A. S. Rury, “Defects Cause Tails in the Optical Spectra of a Crystalline Tetracene Derivative” J. Phys. Chem. Lett. 8, 5993–6001, (2017).

A. P. Moon, R. Pandey, J. A. Bender, D. E. Cotton, B. A. Renard, & S. T. Roberts, "Using Heterodyne-Detected Electronic Sum Frequency Generation to Probe the Electronic Structure of Buried Interfaces" J. Phys. Chem. C. 121, 18653-64, (2017).

R. W. Johns, M. A. Blemker, M. S. Azzaro, S. Heo, E. L. Runnerstrom, D. J. Milliron, & S. T. Roberts, "Charge Carrier Concentration Dependence of Ultrafast Plasmonic Relaxation in Conducting Metal Oxide Nanocrystals" J. Mater. Chem. C. 5, 5757-63, (2017).

M. S. Azzaro, M. C. Babin, S. K. Stauffer, G. Henkelman, & S. T. Roberts, "Can Exciton-delocalizing Ligands Facilitate Hot Hole Transfer from Semiconductor Nanocrystals?" J. Phys. Chem. C.
120, 28224-34, (2016).

A. K. Le, J. A. Bender, & S. T. Roberts, "Slow Singlet Fission Observed in a Perylenediimide Thin Film" J. Phys. Chem. Lett. 7, 4922-28, (2016).

R. Pandey, A. P. Moon, J. A. Bender, & S. T. Roberts, "Extracting the density of states of copper phthalocyanine at the SiO₂ interface with electronic sum frequency generation" J. Phys. Chem. Lett. 7, 1060-66, (2016).

S. T. Roberts, "Energy transport: Singlet to triplet and back again" Nature Chem. 7, 764-765, (2015).

Cottrell Scholars Award, 2018

National Science Foundation CAREER Award, 2017-2022

ACS Petroleum Research Fund Doctoral New Investigator Award, 2015-2017

Rom Rhome Endowed Teaching Excellence Award, 2017

Natural Sciences Foundation Advisory Council Teaching Award, 2014

NSF ACC-F Postdoctoral Fellow, 2010-2011

ACS Physical Chemistry Division Postdoctoral Research Award, 2011

Burg Postdoctoral Teaching Fellowship, 2012