Conjugated polymers polymer conductivity

As mentioned in the introduction, the electrical conductivity upon doping is one of the most important physical properties of conjugated polymers. The conductivity ranges from lOOOOOS/cm for iodine-doped polyacetylene [41], 1000 S/cm for doped and stretched polypyrrole [42], to 500 S/cm for doped PPP [43], 150 S/cm for hydrochloric acid doped and stretched polyaniline [44], and 100 S/cm for sulfuric acid doped PPV [45] to 50 S/cm for iodine-doped poly thiophene [46]. The above listed conductivities refer to the unsubstituted polymers other substitution patterns can lead to different film morphologies and thus to a different electrical conductivity for the same class of conjugated polymer in the doped state. 

Intrinsically conducting polymers are a broad class of (often) processable materials based upon doped -it conjugated polymers. Their conductivities vary from that of insultators through to that of semiconductors and even good metals. A wide variety of electronic phenomena are observed. Because of the broad choice of materials and properties, this class of polymer is potentially of use in a large number of technologies. 

The doped or undoped conjugated polymers having conductivity less than 10" SI cm order show very poor sensing response due to having... 

Conjugated polymers. 2. Conducting polymers. 3. Organic conductors. I. Skotheim, Terje A.,... 

While an invaluable tool in producing conjugated polymers on conducting substrates, electropolymerization has limitations that include a lack of primary structure verification and characterization along with the inability to synthesize large quantities of processable polymer. To overcome the insolubility of PEDOT, a water-soluble polyelectrolyte, poly(styrenesulfonate) (PSS) was incorporated as the counterion in the doped PEDOT to yield the commercially available PEDOT/PSS (Baytron P) (39), which forms a dispersion in aqueous solutions [140]. While this polymer finds most of its application as a conductor for antistatic films, solid state capacitors, and organic electronic devices, its electrochromism is distinct and should not be ignored. 

Proposed more than 10 years ago, a new concept is attracting a lot of interest, the plastic LEDs and plastic lasers [50], which are based on neutral, not conductive conjugated polymers, where conductive polymers are intended to be used as the hole injection layer. But this area has by far not yet reached a market acceptance as has been hoped for or predicted by the active scientists, companies, and the interested public. 

Exciton binding energies comparable to the optical gap. Disorder. Dielectric screening of excitons from both solvation and dispersion interactions. Doped conjugated polymers exhibit conductivity close to a disorder-induced metal-insulator transition. Energy spectra are broadened. 9... 

Li et ai adopted the same approach to prepare nanohbers using conjugated polymers having conductive properties for use in electronics and semiconductor apphcations.lhe polymers used were poly[2-methoxy-5-(2-ethylhexyloxy)-l,4-phenylenevinylene] (MEH-PPV) and poly(3-hexylthio-phene) (PHT) which could not be electrospun into hbers due to Umited solubility. The sheath polymer chosen was PVP which was later extracted using ethanol. The results show that using co-axial spinning technology. 

Feast, W. J., Tsibouklis, J., Pouwer, K. L., Groenendaal, L., and Meijer, E. W., Synthesis, processing and material properties of conjugated polymers. Polymer, 37, 5017-5047 (1996). A review reporting on recent progress especially in the synthesis of well-defined conducting polymers. 

Ionic implantation in polymers is now a well known technique which leads to a very large conductivity increase of the irradiated area when a polymer film is submitted to the action of a high-energy ion beam. After implantation with very high-energy ions, a solid non-conjugated polymer acquires conductive properties, which may find various applications in microelectronics and, in particular, in the production of conductive paths at the surface of an insulator. 

Bashir, T., 2013. Conjugated Polymer-Based Conductive Fibers for Smart Textile Applications. University of Boras, Sweden. 

D. Baeriswyl, D. K. Campbell, and S. Mazumdar, An overview of the theory of 7r-conjugated polymers, in Conducting Polymers (H. Kiess, ed.), Springer-Verlag, Heidelberg, 1992, p. 7. 

Currently, there are several classes of EAPs that have been shown to exhibit conductivities of metals and semiconductors in the doped state. They are the polyacetylenes, poly(para-phenylene)s, polyheterocycles, poly(phenylene vinylenels, polyanilines, and conjugated ladder polymers. Conducting polymers are made by both chemical and electrochemical polymerization. In the neutral (uncharged) state, EAPs are insulators or semiconductors. Oxidized (p-doped) EAPs have had electrons removed from the backbone, resulting in delocalized polymer cation formation. Reduced (n-doped) EAPs have had electrons added to the backbone, resulting in polymer anion formation. 

Polymers. The Tt-conjugated polymers used in semiconducting appHcations are usually insulating, with semiconducting or metallic properties induced by doping (see Flectrically conductive polymers). Most of the polymers of this type can be prepared by standard methods. The increasing use of polymers in devices in the last decade has led to a great deal of study to improve the processabiUty of thin films of commonly used polymers. 

In addition to thermal polymerization, it is possible to polymerize CPD with inorganic haUdes as catalyst. With trichloroacetic acid as the catalyst, deeply colored, blue polymers that conduct electricity in nonpolar solvents such as benzene in the presence of acid can be obtained. The conductivity and color are caused by blocks of conjugated double bonds present in the polymers (20—21). 

Generally speaking, electrically conductive polymers are composed of conjugated polymer chains with TT-electrons delocalized along the backbone. 

Polyheterocycles. Heterocychc monomers such as pyrrole and thiophene form hiUy conjugated polymers (4) with the potential for doped conductivity when polymerization occurs in the 2, 5 positions as shown in equation 6. The heterocycle monomers can be polymerized by an oxidative coupling mechanism, which can be initiated by either chemical or electrochemical means. Similar methods have been used to synthesize poly(p-phenylenes). 

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