Berlin 2008 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 10: POSTERS New Materials, Organic Semiconductors

CPP 10.2: Poster

Montag, 25. Februar 2008, 16:45–19:00, Poster A

Switchable Fluorescence Cell — •Frank Friedriszik, Harald Graaf, Jörg Schuster, and Christian von Borczyskowski — Center of Nanostructured Materials and Analytics, TU Chemnitz, 09107 Chemnitz, Germany

Calamitic liquid crystaline materials are well known and used in a wide spread of display applications. One of the most common material is the 4-pentyl-4-cyanobiphenyl (5CB) which is in the nematic phase at room temperature. Rubbed polyimid films can be used for an orientation of these calamitic liquid crystals in a liquid crystal cell where the molecules are aligned parallel to the substrate and with its axis along the rubbing direction. Due to the permanent dipole moment of the LC molecule an applied electric field perpendicular to the substrate surface will switch the orientation of the molecules parallel to the electric field.
Here we present recent results on the alignment of a rod like organic dye molecule doped into the liquid crystal and which orients within the liquid crystal parallel to the 5CB molecules. Thus, in the liquid crystal cell the organic molecules are oriented parallel to the substrate surface and its orientation will be switched together with the liquid crystal in an electric filed. As the transition dipol of the dye molecule is oriented along the axis of the molecule its luminescence is also switched by the electric fields. Thus we are able to demonstrate a prototype of a switchable fluorescence cell. Besides potential display applications, such a dye which aligns with the liquid crystal is also a perfect probe of local liquid crystal structure.