Physical vapor deposition of organic glasses (Final Report)
- Univ. of Wisconsin, Madison, WI (United States); University of Wisconsin-Madison
As of 2009, when this project began, it had been established that physical vapor deposition (PVD) could produce high density and high stability (“ultrastable”) glasses of two organic molecules. With this project, we established that ultrastability was a quite general result for PVD glasses of organic molecules and, in particular, for the organic semiconductors used to produce organic light emitting diodes (OLEDs). We established that ultrastable glasses have enhanced photochemical and chemical stability, and increased resistance to crystallization. We developed a temperature-gradient deposition stage to more efficiently screen the properties of PVD glasses. We established that PVD glasses are usually anisotropic and that this anisotropy can be controlled. We characterized the unusual transformation mechanism of PVD glasses, which superficially is more similar to crystals than liquid-cooled glasses. In the most recent grant cycle, we extended these results to co-deposition of two organic semiconductors, showing that mixed PVD glasses of these systems usually showed ultrastability and high density; in two cases, co-deposition results in component segregation, and deposition conditions can be adjusted to control domain size. In our work since 2009, we established that the surface equilibration mechanism can successfully explain almost all of the properties of PVD glasses, and that this mechanism can provide useful predictions regarding stability and anisotropy.
- Research Organization:
- Univ. of Wisconsin, Madison, WI (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
- DOE Contract Number:
- SC0002161
- OSTI ID:
- 2475341
- Report Number(s):
- DOE-WISCONSIN--SC0002161-1
- Country of Publication:
- United States
- Language:
- English
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