Dresden 2006 – scientific programme

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HL: Halbleiterphysik

HL 31: Organic semiconductors

HL 31.1: Talk

Wednesday, March 29, 2006, 14:30–14:45, POT 51

Current Limiting Mechanisms in MDMO-PPV Diodes — •Carsten Deibel¹, Vladimir Dyakonov¹, Britta Bohnenbuck², Elizabeth von Hauff², and Jürgen Parisi² — ¹Experimental Physics VI, Physical Institute, University of Würzburg, 97074 Würzburg, Germany — ²Energy and Semiconductor Research Laboratory, Department of Physics, University of Oldenburg, 26111 Oldenburg, Germany

We examined the current-voltage characteristics of poly[2-methoxy,5-(3,7- dimethyloctyloxy)]-1,4phenylenevinylene (MDMO-PPV) diodes in the framework of space charge limited currents (SCLC). The thickness of the MDMO-PPV layer was varied between samples, and the effect of using metal cathodes with different work functions was investigated. Since the basic SCLC model could not explain the experimental data, modifications to it were individually investigated: (1) a double Gaussian density of states to account for deep traps, (2) injection of electrons from the back contact resulting in a recombination current, and (3) the influence of the built-in potential resulting from the asymmetric work functions of the electrodes. The simple SCLC model in combination with the built-in potential and a parallel resistance was able to explain both the thickness and cathode dependence of the current-voltage characteristics.