Prof. Mark Ediger
Title: Glass is more interesting than you thought: surface-mediated assembly of ultrastable and structured states
Abstract: Physical vapor deposition (PVD) can produce glasses with remarkable properties, including high density and high kinetic stability. By some metrics, these are the most stable glasses on the planet. The properties of PVD glasses can be explained by the surface equilibration mechanism. Even though the substrate is held below the glass-transition temperature Tg, the glass surface is highly mobile and this allows incoming molecules to sample many packing arrangements before being buried by further deposition. Initial work in our group with organic glasses has now been extended by others to show aspects of ultrastability in metallic and chalcogenide glasses.
The primary application of PVD glasses is organic light emitting diode (OLED) displays, which are used for almost every cell phone. During PVD, equilibration occurs in an anisotropic environment (the free surface) and this creates the opportunity to form anisotropic glasses. For OLEDs, controlling anisotropy leads to brighter displays and increased stability leads to longer-lived devices. PVD can produce glasses with substantial dipolar order (P1) and orientation order (P2), and even smectic order. Co-deposition allows controlled preparation of domain structures and this may be important for organic photovoltaic devices. The surface equilibration mechanism allows an understanding of all these features, and deposition conditions allow control over the structure of the deposited glasses.
Bio: Mark Ediger received his Ph.D. from Stanford University and is currently the Hyuk Yu Professor of Chemistry at UW-Madison. His research is focused on organic glasses, both polymeric and low-molecular-weight materials. Ediger is currently an Associate Editor for the Journal of Chemical Physics. He has served as Chair of two Gordon Conferences: Polymer Physics and Chemistry and Physics of Liquids. He received the American Physical Society’s Dillon Medal in 1993 and also the Polymer Physics Prize in 2015, as well as the American Chemical Society Hildebrand Award for the Experimental and Theoretical Chemistry of Liquids in 2013.
A reception in the North Tower Atrium will immediately follow the seminar.