IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Organic Films and Devices Wednesday Sessions
       Session OF+NS+SS+BI-WeM

Paper OF+NS+SS+BI-WeM6
Controlling Molecular Orientation in Solid Films Via Self-organization in the Liquid-crystalline Phase

Wednesday, October 31, 2001, 10:00 am, Room 131

Session: Self Assembled Monolayers/Ordered Films
Presenter: S.M. Casey, University of Nevada, Reno
Authors: I.K. Iverson, University of Nevada, Reno
S.-W. Tam-Chang, University of Nevada, Reno
S.M. Casey, University of Nevada, Reno
B.A. Pindzola, University of California, Berkeley
Correspondent: Click to Email
We report the control of molecular orientation in solid films through self-organization and induced-orientation processes. We synthesized water-soluble cationic 3,4,9,10-perylene diimide (1) and studied its self-organization in aqueous solution. By UV-vis spectroscopy, H-aggregates of 1 are observed forming in solutions with concentrations as low as 10@super -7@ M. At concentrations above approximately 0.1 M (7% w/w) these solutions are observed with polarized microscopy to form a chromonic N phase (a nematic lyotropic liquid crystalline phase) at room temperature. Upon induced alignment (by shearing) of the chromonic N phase on a glass substrate and removal of solvent, anisotropic solid films of the dichroic dye are produced. These films have dichroic ratio values that routinely exceed 25 and in some cases 30, making them excellent sheet polarizers over the blue and green region. Using a combination of polarized UV-vis and FT-IR spectroscopies, the orientation of the average molecular plane in these films is determined to be perpendicular to both the shearing direction and the substrate plane. X-ray diffraction studies indicate that the molecules in the solid film possess a high degree of order.