Regensburg 2007 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 2: Organic Thin Films II

DS 2.7: Vortrag

Montag, 26. März 2007, 12:45–13:00, H32

Influence of gas molecules on the electrical characteristics of organic semiconductors — •Harald Graaf¹ and Derck Schlettwein² — ¹Centre for nanostructured materials and analytics, TU Chemnitz, 09107 Chemnitz — ²Institut für Angewandte Physik, Justus-Liebig-Universität Giessen, 35392 Giessen

The stability of the electrical characteristics of organic thin films under ambient conditions is one of the key issues on the way to a product. Gas molecules are an important factor to influence strongly the performance of a number of electronic devices.

We report here on the influence of some selected gas molecules on the electrical properties of organic thin films prepared from perylene dicarboxilic acid bis imides. Thin films of a crystalline (MePTCDI) and an amorphous representative (Cl₄MePTCDI) were prepared by physical vapour deposition. As gas molecules oxygen was chosen as a typical ambient gas and ethanol, acetone and n-butane were chosen as representatives of processing solvents as well as volatile organic compounds in air quality monitoring. All studied gas molecules led to a change in the observed conductivity of the semiconducting films. Field effect measurements served to differentiate between changes in charge carrier mobility and charge carrier concentration and hence increase the selectivity of the measurements. The charge carrier mobility was found to decrease in all cases. Gas molecules which diffused into the bulk effected the mobility at least 10 times more efficiently than molecules whose interaction was restricted to the surface.[1]

[1] H. Graaf, D. Schlettwein, J.Appl.Phys. accepted