Conductivity Doping

AppHcations of polythiophenes being considered utilize either the electrical properties of the doped conducting state with either anionic or cationic... 

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). 

Fig. 1. (a) Comparison of normalised electrical conductivity of individual MWCNTs (Langer 96 [17], Ebbesen [18]) and bundles of MWCNTs (Langer 94 [19], Song [20]). (b) Temperature dependence of resistivity of different forms (ropes and mats) of SWCNTs [21], and chemically doped conducting polymers, PAc (FeClj-doped polyacetylene [22]) and PAni (camphor sulfonic acid-doped polyaniline [2. ]) [24]. 

In principle, such propositions resemble the bipolaron model, which presents the physicist s view of the electronic properties of doped conducting polymers 53-159) The model was originally constructed to characterize defects in solids. In chemical terminology, bipolarons are equivalent to diionic spinfree states of a system (S = 0)... 

Most conducting polymers, such as doped poly(acetylene), poly(p-pheny-lene), and poly(/ -phenylene sulfide), are not stable in air. Their electrical conductivity degrades rapidly, apparently due to reaction with oxygen and/or water. Poly(pyrrole) by contrast appears to be stable in the doped conductive state. 

Instabilities of doped conductive polymers are largely an environmental problem Some polymers when p-doped to the limit have oxidation potentials high enough to attack the most inert solvents. Most will attack water even at much lower doping levels. 

FIGURE 26.6 (a) p-doped conductive polymer in battery cell configuration (b) -doped... 

The first the methods mentioned is based on the monitoring of initial changes in electric parameters (mainly the dope conductivity o) of semiconductor film of sensor caused by adsorption of active particles. In the limiting case this value may be estimated as... 

Electric effects detected in semiconductor oxide films during chemi-sorbtion of atom particles have been also thoroughly studied for chemi-sorbtion of various free radicals CH2, CH3, C2H5, C6H5OH2, OH, NH, NH2, etc. [41]. It was discovered that all of these particles have an acceptor nature in relation to the electrons of dope conductivity in oxide semiconductors their adsorption, as a rule, being reversible at elevated temperatures. It is clear that we deal with reversibility of electron state of the oxide film after it has been heated to more than 250-300°C in... 

In conclusion to this part it seems noteworthy that in contrast to the effect of adsorption of molecular particles on electrophysical properties of oxide semiconductors, the major peculiarity of this effect for such chemically active particles as the simplest free radicals or atoms of simple gases (H2, O2, N2, CI2, etc.) is that they are considerably more chemically active concerning the impurity centres [47]. The latter are responsible for dope conductivity of oxide semiconductors. As for the influence of electric fields on their adsorption due to adsorption-induced surface charge distribution, they are of minor importance which is proved by results of the experiments on assessing field effect on adsorp-... 

See PERCHLORATE-DOPED CONDUCTING POLYMERS See related DIENES... 

Favaro and Fiorani [34] used an electrode, prepared by doping conductive C cement with 5% cobalt phthalocyanine, in LC systems to detect the pharmaceutical thiols, captopril, thiopronine, and penicillamine. FIA determinations were performed with pH 2 phosphate buffer as the carrier stream (1 mL/min), an injection volume of 20 pL, and an applied potential of 0.6 V versus Ag/AgCl (stainless steel counter electrode). Calibration curves were developed for 5-100 pM of each analyte, and the dynamic linear range was up to approximately 20 pM. The detection limits were 76, 73, and 88 nM for captopril, thiopronine, and penicillamine, respectively. LC determinations were performed using a 5-pm Bio-Sil C18 HL 90-5S column (15 cm x 4.6 mm i.d.) with 1 mM sodium 1-octanesulfonate in 0.01 M phosphate buffer/acetonitrile as the mobile phase (1 mL/min) and gradient elution from 9 1 (held for 5 min) to 7 3 (held for 10 min) in 5 min. The working electrode was maintained at 0.6 V versus Ag/AgCl, and the injection volume was 20 pL. For thiopronine, penicillamine, and captopril, the retention times were 3.1, 5.0, and 11.3 min, and the detection limits were 0.71, 1.0, and 2.5 pM, respectively. 

CNT-doped conducting polymers possess improved mechanical, chemical, and optical properties. They also provide a simple strategy for making aligned CNTs. The disappearance of the characteristic peaks of carbon nanotubes in the FTIR spectrum of polymer/CNT composite films is normally an indication of perfect enwrapping of CNTs with the deposited conducting polymer [162, 163], Zhang et al. [40] have studied the... 

The addition of In and Ga and selenization at high temperature were crucial in obtaining the 13.4%-efficient device. Photovoltaic device fabrication was completed by a CBD of about 500 A of CdS, followed by RF sputtering of 500 A of intrinsic ZnO and 3500 A of Al203-doped conducting ZnO. Bilayer Ni/Al top contacts were deposited in an e-beam system. The final step in the fabrication sequence is the deposition of lOOnm of MgF2 as an antirellection coating. 

R Menon, CO Yoon, D Moses, and AJ Heeger, Metal-insulator transition in doped conducting polymers, in Handbook of Conducting Polymers, T.A. Skotheim, R.L. Elsenbaumer, and J.R. Reynolds, Eds., Marcel Dekker, New York, 1998, pp. 27-84. 

ORGANOSILYL PERCHLORATES PERCHLORATE-DOPED CONDUCTING POLYMERS PERCHLORATE SALTS OF NITROGENOUS BASES and the individually indexed entries ... 

Prigodin VN, Hsu EC, Park JH, Waldmann O, Epstein AJ (2008) Electron-ion interaction in doped conducting polymers. Phys Rev B 78 035203... 

Jung JW, Lee JU, Jo WH (2009) High-efficiency polymer solar cells with water-soluble and self-doped conducting polyaniline graft copolymer as hole transport layer. J Phys Chem C 114 633... 

The use of AsF3/AsF5 mixtures as solvents for heavily doped conducting polymers... 

Brown et al. 3S2) have recently emphasised the role of defect structures in heterocyclic polymers. They point out that the reported doped conductivities of these polymers may vary by as much as six orders of magnitude depending on the preparation procedure. They have applied the laser desorption method, discussed earlier for polyphenylene, to a range of polyheterocycles. Unlike polyphenylene, there was evidence for incomplete desorption and rearrangement of evaporated molecules. The results show that polymers prepared by Grignard coupling vary in their extent of bromination, the nature of the terminal species and the extent of formation of cyclic, polynuclear contaminants. 

Elsenbaumer et aL 598> recently made a comparative study of stability of doped conducting polymers in air. They concluded that a combination of a stable polymer with a non-reactive dopant, such as butylthiophene-methylthiophene copolymer doped with FeClg, could give almost indefinite stability in air with an effective ceiling of 50 °C. 

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