Polythiophenes conducting materials

In microelectronics, metalli2ation generally refers to the deposition of a patterned film of conducting material on a substrate to form intercormections between electronic components. Conducting polymers have been demonstrated to provide a new route to metallization, in particular in PCB technology [52]. The conducting polymers that have been of interest in this area include polyanfline, polypyrrole, and polythiophene. 

Hotta, S. (1997) Molecular conductive materials polythiophenes and oligothiophenes, in Handbook of Organic Conductive Molecules and Polymers, 1st edn (ed. H.S. Nalwa), John Wiley Sons, Ltd, Chichester, pp. 309-387. 

Since the discovery of a highly conductive polyacetylene film in 1977 [33], various conductive materials have been developed based on the polymerization of five-membered heteroaromatics represented by polythiophene (2). Polyselenophene (3) was also obtained by chemical polymerization [34-36] or electrochemical polymerization of selenophene (Scheme 6.2) [37-39]. The bandgap energy of polyselenophene... 

Since side-chain-type LC polyacetylene derivatives were first synthesized [10-18], various types of LC conjugated polymers have been synthesized and evaluated from the standpoint of their electrical and optical properties [19-46]. Among them, LC aromatic conjugated polymers, including LC polythiophene derivatives, have been of recent interest because they are available for linearly polarized luminescent materials, and also anisotropically conducting materials [28-30, 40-53]. 

The bandgap of PEDOT ( g = 1.6-1.7 eV)itselfis 0.5 eV lower than polythiophene, which results in an absorbance maximiun in the NIR region. Compared to other substituted polythiophenes, these materials exhibit excellent stability in the doped state which is associated with high conductivity. Doped PEDOT is almost transparent in the visible region (with a sky-blue tint) and the neutral polymer is deep blue. Because PEDOT and its alkyl derivatives are cathodically-coloring electrochromic materials, they are suitable for use with anodically-coloring conducting polymers in the construction of dual polymer ECDs (63). 

Polypyrrole and polythiophene, both first described in 1963 as electrically conducting materials [la], experienced a renaissance when Diaz and Street gave new attention to the electrochemical oxidation of pyrrole [21], and Gamier to the polythiphene field transistor. Polyphenylene vinylene, polyaniline, polyphenylene sulfide, polycarbazole, polyindole, polypyrene and polyene fulvene are just a few of the large number of electrically conducting polymers with specific properties and interest [22]. 

Polythiophenes in the neutral state are stable in the dark under atmospheric conditions but the conductivity of doped polythiophene and poly(3-alkylthiophene)s decreases rapidly. This lack of stability is one of the major barriers to industrial application of polythiophenes as conductive materials. Extrinsic and intrinsic factors determine the stability of a conductive polymer. Extrinsic instability is mainly due to the reaction of the charged defects with water vapor and oxygen. A... 

We have outlined the synthesis, structural characterization, spectroscopic and electronic features, and charge transport properties as well as electronic device applications of the molecular conductive materials of polythiophenes and oligothiophenes. These materials have been characterized and described as those comprising thiophene ring units and were shown to exhibit unique structural and electronic properties as a function of the number of those units (oligomer to polymer). 

Molecular Conductive Materials Polythiophenes and Oligothiophenes S. Hotta... 

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. 

Polypyrroles and polythiophenes are known to be highly conducting materials, particularly, when they are synthesized electrochemically. Their synthesis is accompanied by a simultaneous doping of the polymer by the anions of the supporting electrolyte such as tetrafluoroborate or toluene sulfonate anions that are incorporated in the structure as counterions to the polycations which are segments of the conjugated chains. Regardless of the anions size and nature, the materials are insoluble in any solvent. 

A conducting polymer chosen for these potential applications was polythiophene and its 3-methyl derivative. These polymers represent a class of tractable, conducting materials which exhibit facile and reversible electrochemistry, hen in the oxidized form, these polymers become metallic ( a n 10 - 10 S/cm). Thin films of polythiophene and its derivatives supported on various substrates can be made in situ from the appropriate monomers. Polythiophenes are additionally attractive from the standpoint that their electrochemical and physical properties are readily altered via substituent groups (12). The present work investigates the electrochemical properties of polythiophene and its 3-methyl derivative in liquid Li(S02) AlCl. ... 

For polymer-based devices, conducting polymers such as polyanaline and polythiophene have been used extensively as anodes. These are naturally p-type (hole conducting) materials produced by oxidation of conjugated molecules and thus are naturally suited to mediating the hole injection problem. However, these materials are not ideal. The polymer devices have generally lagged behind the molecular-based devices, probably in part, because more intensive study and improvement of contacts has been pursued for the molecular materials. 

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