Regensburg 2007 – wissenschaftliches Programm

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SYOE: Symposium Organic Thin Film Electronics: From Molecular Contacts to Devices

SYOE 8: Poster Session SYOE

SYOE 8.72: Poster

Dienstag, 27. März 2007, 18:00–20:00, Poster B

Magnetoresistance in organic semiconductors — •Ulrich Niedermeier^1,2, Michael Vieth¹, Wiebke Sarfert¹, Manfred Rührig¹, Ralph Pätzold¹, and Heinz von Seggern² — ¹Siemens AG, CT MM 1, Günther-Scharowsky-Str. 1, 91058 Erlangen, Germany — ²TU Darmstadt, Department of Materials Science, Petersenstr. 23, 64287 Darmstadt, Germany

Organic semiconductors are promising materials for use in novel electronic devices such as organic light emitting diodes (OLEDs). Recently it has been demonstrated that the resistance of OLEDs changes in the presence of an external magnetic field [1]. The organic magnetoresistance (OMR) effect is isotropic regarding the direction of the magnetic field and can be observed at room temperature. Since the investigated structures do not contain any ferromagnetic materials the OMR is to be distinguished from the well-known giant magnetoresistance in spin-valve structures. We performed magnetoresistance measurements and electro-optical characterizations of various OLED structures. As a result we show the dependence of the OMR effect on both the magnitude of the magnetic field and the voltage applied to the OLEDs. Furthermore, we point out that the OMR effect can be influenced by varying the materials of the organic layers and the cathode.

[1] T. Francis, Ö. Mermer, G. Veeraraghavan, M. Wohlgenannt,
New J. Phys. 6, 185, 2004.