Berlin 2008 – wissenschaftliches Programm

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SYSA: Symposium Tayloring Organic Interfaces: Molecular Structures and Applications

SYSA 5: Poster Session SYSA

SYSA 5.25: Poster

Dienstag, 26. Februar 2008, 14:30–20:00, Poster A

Charge transfer doping of organic diodes: A theoretical study — •Oliver Ottinger, Christian Melzer, and Heinz von Seggern — Electronic Materials Division, Institute of Materials Science, Technische Universität Darmstadt, Petersenstr. 23, 64287 Darmstadt, Germany

Charge transfer doping is a promising concept for improving charge injection from metals into organic semiconductors. A self-consistent model of an unipolar electron-only metal/insulator/metal (MIM) diode based on drift diffusion theory was applied. It allows for the description of injection as well as space charge limited currents. The model was extended by charge transfer doping with arbitrary doping profiles. Besides modelling the steady state current density-voltage characteristics and the respective electric field- and charge carrier distributions, the response on an ac disturbance has been considered in order to model impedance measurements. Simulations were done for bulk doped and near-interface doped diodes.

It will be shown, that doping in the vicinity of the cathode results in an improved device performance. This stems from an electric field induced inherent barrier lowering promoting the electron injection. A bulk doped MIM system can be well understood as two Schottky diodes in series while one is forward and the other is reverse biased. Simulating CV characteristics it was shown that both resulting depletion capacitances determine the time dependent characteristics of the device.