Regensburg 2010 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 12: Poster: Electronic and Optical Properties of Organic Systems
CPP 12.1: Poster
Montag, 22. März 2010, 16:30–18:00, Poster C
Photo-Induced Phase Changes in Azobenzene-Containing Materials — •Hubert Audorff1, Lothar Kador1, Roland Walker2, and Hans-Werner Schmidt2 — 1University of Bayreuth, Institute of Physics and BIMF, D-95440 Bayreuth, Germany — 2University of Bayreuth, Macromolecular Chemistry I and BIMF, D-95440 Bayreuth, Germany
The photo-induced formation of liquid-crystalline phases in azobenzene-containing amorphous materials is demonstrated. Liquid-crystalline polymers and low-molecular-weight glass formers can be quenched into a stable amorphous phase at room temperature. During the inscription of holographic intensity gratings, the illuminated areas become liquid-crystalline, which stabilizes the orientation of the azobenzene units, leading to stable gratings. Another advantage of the quenched polymeric materials is that the writing times are shorter by several orders of magnitude as compared to liquid-crystalline azobenzene compounds. With a series of low-molecular-weight tris-azobenzene derivatives, a remarkably stable light-induced orientation of the chromophores in initially amorphous thin-film architectures is demonstrated for the first time. The liquid-crystalline character is caused by spacers between the tris-functionalized benzene core and the three azobenzene moieties as well as polar end groups. The formation of the liquid-crystalline phase manifests itself in a pronounced post-development of the inscribed ratings, i. e., an increase of the diffraction efficiency after the end of the writing process.