P. Gregory Van Patten 291 Clippinger Laboratories 740-597-1849 740-593-0148 (Fax) vanpatte@ohio.edu Group Page

Honors and Awards:

• Jeanette G. Grasselli Brown Teaching Award, Ohio University, 2004
• Alexander von Humboldt Fellowship for Experienced Researchers, 2008

Research Interests:

Synthesis, Characterization, and Photophysical Studies of Semiconductor Nanocrystals

We are presently studying several different types of colloidal semiconductor nanocrystals, which are also known as "quantum dots." These materials have interesting optical and electronic properties that depend not only on their chemical composition, but also on their size and shape. They are the focus of intense research around the globe due to their potential application in key areas such as biomedical imaging and cancer diagnosis, solar energy conversion, high-efficiency light-emitting devices, optical communications, quantum computing, spintronics, and flexible optical displays.

Our research group is presently exploring a variety of quantum dot materials, including some that have seen little attention so far. These include materials such as gallium nitride, indium nitride, and zinc phosphide, as well as nanoheterostructures that contain two or more semiconductor materials in each nanocrystal. Most typically, these nanoheterostructures are core/shell structures in which the presence of the shell either enhances luminescence (important for light-emitting applications) or promotes photo-induced charge transfer (important for solar energy applications). One particular area of emphasis is the study of new shell materials for lead (II) sulfide quantum dots with an eye toward understanding how different core/shell combinations can help us to control photo-induced charge separation.

Our group routinely employs a wide variety of structural characterization techniques, including x-ray diffraction, transmission electron microscopy, dynamic light scattering, and elemental analysis. Optical and electronic properties are probed using UV-visible-near infrared absorption spectroscopy, photoluminescence spectroscopy, time-resolved photoluminescence, and femtosecond transient absorption spectroscopy. A major goal of our research is to understand the correlation between the structure and the optical/electronic properties of these materials. It is hoped that better understanding of this correlation will enable us to rationally design superior materials for next generation technologies.

Quantum dot research demands expertise in a variety of different areas, including synthesis using an inert gas glovebox and Schlenk line, product purification and characterization, ultrafast spectroscopic measurements, and quantum dot electronic structure theory. All students that graduate from our research group master the full range of knowledge and skills needed to perform cutting-edge quantum dot research. This broad expertise provides excellent preparation for a career in materials chemistry. Recent doctoral graduates have found work in the high-tech materials industry, in university faculty positions, and in post-doctoral positions at leading research universities.

Selected Publications

Yan, Y., Wang, L., Vaughn, C. B., Chen, G., Van Patten, P. G. (2011). Spectroscopic Investigation of Oxygen Sensitivity in CdTe and CdTe/CdS Nanocrystals. Journal of Physical Chemistry C, 115, 24521-24527 dx.doi.org/10.1021/jp2067638

Yan, Y., Chen, G., Van Patten, P. G. (2011). Ultrafast Exciton Dynamics in CdTe Nanocrystals and CdTe/CdS Core/Shell Nanocrystals. Journal of Physical Chemistry C, 115, 22717-22728. dx.doi.org/10.1021/jp204420q

Van Patten, P. G. (2008). Enhancement of optical gain in semiconductor nanocrystals through energy transfer. Journal of Physical Chemistry C, 112, 10622-10631.

Pan, G. Q., Kordesch, M. E., Van Patten, P. G. (2006). Room-temperature synthesis of GaN nanopowder. Chemistry of Materials, C, 18, 5392-5394.

Pan, G. Q., Kordesch, M. E., Van Patten, P. G. (2006). New pyrolysis route to GaN quantum dots.Chemistry of Materials, C, 18, 3915-3917.

Wu, D. G., Kordesch, M. E., Van Patten, P. G. (2005). A new class of capping ligands for CdSe nanocrystal synthesis. Chemistry of Materials, C, 17, 6436-6441.