Vapor-Deposited Glasses with Long-Range Columnar Liquid Crystalline Order
Toney, Michael F.
Ediger, M. D.
American Chemical Society
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Anisotropic molecular packing, particularly in highly ordered liquid crystalline arrangements, has the potential for optimizing performance in organic electronic and optoelectronic applications. Here we show that physical vapor deposition can be used to prepare highly organized glassy solids of discotic liquid crystalline systems. Using grazing incidence X-ray scattering, atomic force microscopy, and UV–vis spectroscopy, we compare three systems: a rectangular columnar liquid crystal, a hexagonal columnar liquid crystal, and a nonmesogen. The packing motifs accessible by vapor deposition are highly organized for the liquid crystalline systems with columns propagating either in-plane or out-of-plane depending upon the substrate temperature during deposition. The structures formed at a given substrate temperature can be understood as resulting from partial equilibration toward the structure of the equilibrium liquid crystal surface during the deposition process.