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CPP: Chemische Physik und Polymerphysik

CPP 23: POSTER Functional Organic Thin Films

CPP 23.11: Poster

Donnerstag, 30. März 2006, 17:00–19:00, P2

Doping and Diffusion Properties of Alkali Metals in PTCDA Thin Films — •Kathrin Heimer, Jens Wüsten, Steffen Berger, Stefan Lach, and Christiane Ziegler — University of Kaiserslautern, Department of Physics, 67663 Kaiserslautern

n-doping of the molecular organic semiconductor perylene-3,4,9,10-tetracarboxylic-dianhydride (PTCDA) is often achieved by evaporation of alkali metals onto the surface of the PTCDA film. It is expected that there are differences in the doping behaviour between the alkali metals [1]. Furthermore it has been believed that the dopant shows a diffusion profile through the layer with most of the dopant accumulated in the first few layers [2].

In this contribution both experimental results concerning chemical composition ((angle resolved) X-ray photoemission spectroscopy ((AR-)XPS), Fouriertransform infrared spectroscopy (FT-IR), electronic structure (ultraviolet photoemission spectroscopy (UPS)), inverse photoemission spectroscopy (IPE)) [3] and theoretical results concerning FT-IR are shown before and after doping with three different alkali metals, sodium, potassium and cesium, respectively.

These results suggest that the three alkali metals diffuse into and react with the PTCDA film in different ways. Models for the dopant distributions are suggested.

[1] K. Heimer, Ch. Ziegler, in preparation

[2] J. Wüsten, Th. Ertl, Ch. Ziegler, Appl. Surf. Sci. 252 (1), 104-107 (2005)

[3] J. Wüsten, S. Berger, K. Heimer, S. Lach, Ch. Ziegler, J. Appl. Phys. 98, 013705 (2005)