LRSM Seminar: “Expanding Our Vision of Glasses: Physical Vapor Deposition Prepares Ultrastable and Anisotropic Materials”
January 27 at 10:30 AM - 12:00 PM
Glasses are generally regarded as disordered and the idea of “controlling” molecular packing in glasses is reasonably met with skepticism. However, as glasses are non-equilibrium materials, a vast array of amorphous structures are possible in principle. Physical vapor deposition (PVD) produces glasses with properties that cannot be achieved by other preparation routes, including high stability and controlled anisotropy. The exotic properties of PVD glasses can be explained by a surface equilibration mechanism: mobility near the free surface allows substantial equilibration during deposition, even well below the conventional Tg. Initial work with organic glasses has now been extended to show aspects of ultrastability in metallic and chalcogenide glasses.
The active layers in commercial OLEDs are PVD glasses of organic semiconductors. Ultrastable glasses of organic semiconductors make longer-lasting OLEDs and in-plane orientation of emitter molecules produces more efficient OLEDs. Co-deposition of two organic semiconductors often produces a homogeneous ultrastable glass but, in other systems, component separation occurs in the plane of the sample, on a controllable length scale.
Mark Ediger
Hyuk Yu Professor of Chemistry, Department of Chemistry, University of Wisconsin–Madison
Mark Ediger received his Ph.D. from Stanford University in 1984 and moved to the University of Wisconsin-Madison as an assistant professor in the Department of Chemistry. He is the Hyuk Yu Professor of Chemistry (Emeritus) at UW-Madison. His research is focused on organic glasses, both polymeric and low-molecular-weight materials. His research projects include mobility induced in glasses by deformation and the formation of ultrastable and anisotropic glasses by physical vapor deposition. Ediger has served on advisory boards for Macromolecules, the Journal of Polymer Science B: Polymer Physics Edition, and the Journal of Chemical Physics, and 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. He is a Fellow of the American Association for the Advancement of Science.