Stable Glasses of Organic Semiconductor Resist Crystallization

TitleStable Glasses of Organic Semiconductor Resist Crystallization
Publication TypeJournal Article
Year of Publication2021
AuthorsBagchi, Kushal, Marie Fiori, Camille Bishop, M. F. Toney, and M. D. Ediger
JournalJournal of Physical Chemistry B
Start Page461
Date Published01/2021

The instability of glassy solids poses a key limitation to their use in several technological applications. Well-packed organic glasses, prepared by physical vapor deposition (PVD), have drawn attention recently because they can exhibit significantly higher thermal and chemical stability than glasses prepared from more traditional routes. We show here that PVD glasses can also show enhanced resistance to crystallization. By controlling the deposition temperature, resistance toward crystallization can be enhanced by at least a factor of ten in PVD glasses of the model organic semiconductor Alq3 (tris(8-hydroxyquinolinato) aluminum). PVD glasses of Alq3 first transform into a supercooled liquid before crystallizing. By controlling the deposition temperature, we increase the glass → liquid transformation time thereby also increasing the overall time for crystallization. We thus demonstrate a new strategy to stabilize glasses of organic semiconductors against crystallization, which is a common failure mechanism in organic light emitting diode devices.