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Elektrisch leitfähige Plasmapolymere

: Kruse, A.; Baalmann, A.; Hennecke, M.

Dünne Schichten 4 (1993), No.1, pp.40-43
ISSN: 0941-7168
Journal Article
Fraunhofer IFAM ()
Eigenleitfähigkeit; electrical conductivity; plasma polymerization; plasmapolymerisation; Thiophenderivat; thiophene

A 2.45 GHz microwave low pressure plasma was used in order to form intrinsically conductive plasma polymers. The electrical conductivity and structure of the polymeric films are compared with those of electrochemically polymerized polythiophene. A new way of doping was tested using the iodine containing monomer 2-iodothiophene. Films with high electrical conductivity (10highminus1 down to 10highminus6 S cmhighminus1) could be realized and their chemical structure was studied by XPS and FTIR. Low contents of iodine are found in the plasma polymerized films. The I3dsub5/2 peak in XPS indicates the existence of different chemical states for iodine in the films, mainly I3minus and I5minus and covalently bound iodine were identified. Especially these oxidation states for iodine may be important for the conduction mechanism. In the IR-spectra of these films the characteristic absorption bands of the thiophene ring are detected. This gives a strong indication that the chemical structure of th ese films are comparable to that of electrochemical deposited polythiophene. Optical emission spectroscopy provided in-situ information about the fragmentation mechanism in the plasma. Based on the combined spectroscopic findings a reaction model for iodine, especially for the forming of volatile species like ICH3 and HI and of the deposited species I3minus and I5minus is proposed.