We use physical vapor deposition (PVD) to prepare what are very likely the most stable glasses ever made in a laboratory. In an afternoon, we can make glasses that have properties that could be achieved by other methods only if the preparation time could exceed thousands of years. As a result, glasses prepared in our lab can have radically different properties than glasses prepared with normal methodology. For example, we have shown that our glasses are more dense and energetically more stable than ordinary glasses. These stable glasses may have immediate technological relevance, e.g., to stabilize the active layers in organic electronic devices. Additionally, the molecules in our vapor-deposited films are not oriented isotropically. Molecular orientation could have a significant impact on the electrical conductivity of organic semiconductors prepared in this way.
In comparison to ordinary glasses, our glasses are much deeper in the energy landscape that controls the thermodynamics and kinetics of an amorphous system. We are learning about important features of the energy landscape that could not previously be explored.
We can vary deposition conditions to prepare glasses with different properties. We have two vapor deposition chambers and we use nanocalorimetry, dielectric spectroscopy, wide angle x-ray scattering and ellipsometry to understand the structure and properties of these materials. In particular our projects are focused in understanding the mechanisms by which stable glasses form and controlling molecular orientation in PVD glasses.