Dresden 2009 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 44: Organic semiconductors I
HL 44.8: Talk
Thursday, March 26, 2009, 12:45–13:00, POT 51
Enhanced magnetoresistance in organic light emitting diodes — •Ulrich Niedermeier1,2, Wiebke Sarfert1, Sergey Bagnich2, Christian Melzer2, and Heinz von Seggern2 — 1Siemens AG, CT MM 1, Günther-Scharowsky-Str. 1, 91058 Erlangen, Germany — 2Technische Universität Darmstadt, Fachbereich Material- und Geowissenschaften, Petersenstr. 23, 64287 Darmstadt, Germany
Magnetic fields can influence the electro-optical properties of organic light emitting diodes via the organic magnetoresistance effect. We investigated the magnetoresistance in poly(paraphenylene vinylene)-based devices as a function of magnetic field and driving voltage. Electrical conditioning at high current densities has been identified as an efficient method to significantly enhance the magnetoresistance effect [1]. Depending on duration and intensity of the conditioning process the absolute value of the magnetoresistance effect can be increased from 1 % to values even exceeding 20 % at 4 V and 40 mT. Qualitatively, the increase in magnetoresistance during conditioning can be correlated with a decrease in electro- and photoluminescence. We attribute these results to a change in the charge carrier transport properties of the bulk emitter material during conditioning. Finally, we discuss our results in the framework of recently published theories on the possible origin of the organic magnetoresistance effect.
[1] U. Niedermeier et al., Appl. Phys. Lett. 92, 193309 (2008).