Dresden 2006 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 21: SYMPOSIUM Functional Organic Thin Films II
CPP 21.2: Vortrag
Donnerstag, 30. März 2006, 14:30–14:45, ZEU Lich
Ambipolar charge transport in the blend systemC60/CuPc — •Andreas Opitz, Markus Bronner, and Wolfgang Brütting — Experimental Physics IV, University of Augsburg, 86135 Augsburg, Germany
In recent years, large progress has been made in the realization of electronic circuits based on organic field-effect transistors (OFETs). However, these circuits as being built-up of unipolar (mostly p-type) OFETs only, have a number of drawbacks. To overcome them, recently, ambipolar OFETs have been suggested as a first step towards complementary organic circuits.
In this work we are analysing the ambipolar charge transport in blend systems of small organic molecules. These mixed layers are prepared by co-evaporation of n-conducting fullerene (C60) and p-conducting copper-phthalocyanine (CuPc) on pre-structured TFT-substrates. It was found that the electrical characteristics (e.g. mobilities of holes and electrons) depend strongly on the composition of the blend and on the preparation conditions like substrate treatment and substrate temperature during the evaporation. The preparation parameters act on the film morphology analysed by scanning force microscopy and on the electrical properties of the films. We further demonstrate ambipolar and complementary inverters with these materials as a basic constituent of more complex organic electronic circuits. Comparison with simulations based on an analytical model [1] shows that asymmetric mobilities and threshold voltages have to be avoided to reduce shifts in the inverter transfer curves.
[1] R. Schmechel et al., J. Appl. Phys. 98 (2005) 084511.