Application of Electrically Conductive Polythiophenes

The best condition for broad applications are soluble or fusible electrically conductive polymeric materials that can be processed from solution or from the melt in order to form compact electrically conductive parts. Thin layers - possible by casting from solution - can also be prepared electrochemically on surfaces that can be handled as electrodes in order to create electrically conductive coatings. 

Generally highly electrically conductive materials arising from polythiophene are available from the appropriate polythiophene with processable properties after oxidation with an oxidant in order to produce the oxidized form (p-type doped form) or after reduction with a reductant to produce the reduced form (n-type doped form) of the polymer in the case of chemical preparation. In the case of electrochemical formation of polythiophene or its derivatives starting from thiophene or suitable derivatives automatically the oxidized, neutral or reduced form of the electrically conductive material can be built up. 

In 1991 the first electrically conductive material, poly(3,4-ethylenedioxythiophene-2,5-diyl) itself or blends of this material and polystyrenesulfonic acid were used to produce transparent, abrasion-resistant, non-corrosive coatings for photographic films and other materials with controlled antistatic properties [11] they came onto the market and can now be used on a commercial scale (see section 10.3). Many applications for polythiophene have been claimed for different piuposes. They are described in scientific papers or patents some are in use for special technical applications or will come on the market in the near future. 

The multiple potential technolo cal applications of polythiophenes can be divided into three main groups  

Many products simply arising from thiophene or its derivatives have been claimed to be useful as electrically conducting materials. In this section a short overview will be given about these materials, their structures, their preparation and the values of their electrical conductivity. It is essential, that such polymers are oxidized (/7-type doped) or reduced (n-type doped) for enhanced electrical conductivity (for reviews see [12-14]. In all cases the electrical conductivity of the neutral form is about 10 to 10 Scm . 

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