Papanikolas Group

Ultrafast Spectroscopy and Ultrafast Microscopy

Papanikolas Group (2013)

Front Row (left to right): Li Wang, Ernest Vallorz, Stephanie Bettis, Melissa Gish, Emma Cating, Michelle Gabriel, Will Fondrie. Back Row (left to right): Alexander Gilligan, David Zigler, Justin Kirschbrown, Zach Morseth, Erik Grumstrup, Robert Brown, Aaron Brown, John Papanikolas

Ultrafast Dynamics of Solar Energy Conversion


Ultrafast Spectroscopy • Ultrafast Microscopy
Computer Simulation and Modeling •


Nanoscale Materials • Nanodevices • Photonics • Molecular Assemblies • Electron Transfer • Energy Transfer


Ultrafast spectroscopy enables one to follow the dynamics of chemical systems  in “real time.” Our group is  using ultrafast techniques, and developing new ones, to characterize the fundamental photophysical events that underpin solar energy conversion.  We are using time-resolved absorption and emission methods to characterize energy and electron transfer in molecular materials used in solar fuels applications. We are also pursuing new ultrafast microscopy methods that can excite a single structure in one location and probe it in another. These methods enable the direct visualization of charge flow  in individual  semiconductor nanostructures used in solar photovoltaic, photonic, and nanoelectronic applications. Experimental observations are combined with computer simulations (finite element methods and molecular modeling) to develop a detailed picture of how the structure and shape of an object influence its photoinduced dynamics.


Our research has benefited from collaborations with a number of groups that are experts in the synthesis of molecular assemblies and nanomaterials. Collaborators include Thomas Meyer (UNC-CH), James Cahoon (UNC-CH), Marcey Waters (UNC-CH), Kirk Schanze (University of Florida), and John Reynolds (GA Tech).

Research Funding

Support for our research has come  from the National Science Foundation, the UNC Energy Frontier Research Center,  the Department of Energy, the National Aeronautics and Space Administration, the Army Research Office, the ACS Petroleum Research Fund, and the Research Corporation

Ultrafast Microscopy: Visualizing Charge Carrier Motion

Controlling the flow of charges through nanostructures is central to their function in photovoltaics, LED devices, and nanoelectronics. We are developing femtosecond pump-probe microscopy techniques that directly image the motion and lifetimes of charges in semiconductor nanowires and nanowire networks.

Molecular Materials for Solar Energy Conversion

Light-harvesting and charge separation are central solar energy conversion. We are using ultrafast spectroscopy to characterize these fundamental processes in molecular materials. Our research informs the development of molecular assemblies for solar fuels applications.

Development of New Ultrafast Methods

The design and construction of spectroscopic instrumentation is an integral part of our research. In addition to femtosecond transient absorption and time-resolved emission spectroscopies, which are used on routine basis,  current projects are developing ultrafast microscopy and femtosecond Raman spectroscopies.

Recent Publications

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Papanikolas Group
Department of Chemistry
University of North Carolina at Chapel Hill