Ageing Of Electrically Conducting Organic Materials

Abstract Ageing with respect to conductivity has been investigated for a wide variety of organic materials ranging from polyacetylene and polypyrrole salts to carbon black and carbon fibres, which are conducting materials in their electrically neutral state. For two polyacetylenes of different composition and a polypyrrole phenylsulphonate the influence of temperature on conductivity and its change with time could be described quantitatively. Data on the stability of polypyrrole salts under humidity and under extreme inert conditions are given. The influence of the degree of oxidation on the stability under ambient conditions is reported for a polypyrrole perchlorate. A comparison of the stability of the conductivity of organic salts like tetrathiofulvalene/tetracyanoquinoline (TTF/TCNQ) and those based on polyacetylene, polypyrrole, polythiophene and polyaniline with carbon black and carbon fibres, which are conductive in their neutral state, gives rise to the assumption that carbenium ion-structures are not stable with respect to the attack of oxygen and water. Covalent bonds cause the decrease in conductivity.