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Anomalous current–voltage characteristics of thin polymer films

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2003

Year

Abstract

In this paper we have investigated organic light emitting diodes with such electroluminescent materials as aromatic polyimide, poly∼N-vinylcarbazole (PVK) and dye doped PVK. N-type current–voltage characteristics with negative differential resistance for the thin polymeric and organic films are analyzed. No reasonable explanation has been provided for this phenomenon until now. Here we suggest that a polymer(organic)/metal interface containing various inhomogeneities and metal spikes is responsible for this effect. We detect also the black-body radiation, whose temperature exceeds both the melting point and the sublimation temperature of the metal of the electrode. We suppose that the current density through the spike in any cases is large enough to cause the explosion of the tip of the spike and the detected radiation has the hot plasma origin. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)