Dresden 2003 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 20: POSTER A
CPP 20.48: Poster
Montag, 24. März 2003, 19:00–21:00, ZEU/250
The effect of sensitizing of an organic photorefractive material on its dynamics — •Andre Leopold1, Dietrich Haarer1, Jolita Ostrauskaite2, and Mukundan Thelakkat2 — 1Experimentalphysik IV und BIMF, Universität Bayreuth, Universitätsstr. 30, 95447 Bayreuth — 2Makromolekulare Chemie I und BIMF, Universität Bayreuth, Universitätsstr. 30, 95447 Bayreuth
The photorefractive (PR) effect in organic photorefractive materials arises when charge carriers, generated by an inhomogeneous distribution of light intensity, are separated by an external field and subsequently trapped. Thereby they are creating a nonuniform space-charge distribution and give rise to the photorefractive effect. The observable which is measured in holographic experiments however is the modulation of the refractive index. The refractive index is modulated mainly by two contributions: the non-linear optical (Pockels) effect and a contribution due to birefringence in low-Tg polymers caused by the reorientation of anisotropic chromophores. Due to this complex interaction of different processes, separating different parts of the contribution to the PR effect will lead to a deeper understanding of its dynamics. The first and primary process is the generation of mobile charge carriers. This is usually achieved by the addition of a small concentration of a sensitizer such as the fullerene C60 which increases the absorption. We altered the sensitizer concentration from 0.1 wt% to 5 wt% to affect the space-charge field creation. A strong influence on the build-up speed of this space-charge field can be seen. Our results and their correlation with the photorefractive standard model will be discussed in this presentation.