ChEM seminar: Physical vapor deposition and characterization of highly ordered organic glasses
This event is in the past.
Dr. Camille Bishop
Organic glasses, a broad term for organic solids with no long-range crystalline order, are ubiquitous in modern technologies, such as in OLED displays. Despite a lack of long-range order, glasses can be made to have highly organized amorphous molecular packing by using physical vapor deposition (PVD). In PVD, glass-forming molecules are evaporated and deposited onto a temperature-controlled substrate. The key to the unique anisotropic (ordered) structure in these glasses is the “layer-by-layer” assembly of PVD, in which the molecules are highly mobile when they first hit the free surface, and then slow and become locked into place by subsequent layers of molecules burying them. When the thermodynamically preferred packing at the free interface is structured, this results in a highly ordered film composed of many layers of “frozen” surface. By choosing optimum deposition conditions, such as the temperature of the substrate and the deposition rate, the exact degree of anisotropy can be dialed in to tailor materials for various applications. The glasses are characterized by a combination of optical and X-ray methods to gain insight into the molecular mechanisms of assembly. Additionally, new cutting-edge X-ray measurement techniques using resonant X-ray absorption and scattering are employed. These new techniques enhance the measurement of glassy structure down to individual chemical bond correlations. Our improved understanding of the origin of highly ordered packing allows us to enhance properties such as charge mobility and efficiency in organic electronic devices.
Dr. Camille Bishop is an NRC Postdoctoral Fellow at the National Institute of Standards and Technology (NIST), where she is working on developing polarized resonant soft X-ray scattering (p-RSoXS) and its application to characterizing multi-component glasses and semi-crystalline polymers. She obtained her Ph.D. in Chemistry from the University of Wisconsin – Madison, where she studied physical vapor deposition of highly ordered organic glasses with Mark Ediger. She obtained a B.S. in Chemistry from the University of Chicago.
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