Conductivity photoconductivity

Kabanov [351] has provided an excellent review of the application of measurements of electrophysical effects in studies of the thermal decomposition of solids, including surveys of electrical conductivity, photoconductivity, dielectric measurements and interface (contact), Hall and thermal (Seebeck) potentials. Care must be exercised in applying the results obtained in such studies to the interpretation of data for thermal decomposition in the absence of an applied electric field since many examples have been given [352] in which such a field markedly influences the course of decomposition. 

Like dark conductivity, photoconductivity increases rapidly with the concentration of the doping compound [see Eq. (51)]. Suitable doping agents can give photoconductive gains G > 1 52>. 

As explained in the introduction, the polysilanes (and related polygermanes and poly-stannanes) are different from all other high polymers, in that they exhibit sigma-electron delocalization. This phenomenon leads to special physical properties strong electronic absorption, conductivity, photoconductivity, photosensitivity, and so on, which are crucial for many of the technological applications of polysilanes. Other polymers, such as polyacetylene and polythiophene, display electron delocalization, but in these materials the delocalization involves pi-electrons. 

One single property of filler - electric conductivity - affects many properties of the final products. These properties include electric insulation, conductivity, superconductivity, EMI shielding, ESD protection, dirt pickup, static decay, antistatic properties, electrocatafysis, ionic conductivity, photoconductivity, electromechanical properties, thermo-electric conductivity, electric heating, paintability, biocompati-bilify, etc. Possession of one of these properties in a polymer can make it useful in industiy and eveiyday use. Examples are given in Chapter 19. Here, the electrical... 

The importance of nonstoichiometry lies in the fact that many physical properties such as color, diffusivity, electrical conductivity, photoconductivity, and magnetic susceptibility can vary markedly with small changes in composition. 

PROPERTIES OF SPECIAL INTEREST Electrical Conductivity, photoconductivity, and nonlinear optical activity. 

Conductivity, photoconductivity, and chromophore electrostatic interactions almost certainly account for the disappointing and erratic results that were initially obtained for the high-/x/3 chromophores of Table 2. Utilization of the data of recent studies has permitted rectification of these problems. 

A metal ion M as part of a polymer chain is surrounded by a multivalent ligand. As a result, stacked arrangements 107 are realized with a face-to-face orientation of the ligands. Porphyrins, phthalocyanines, naphthalocyanines, etioporphyrin, tetraaza[14]annulene, hemiporphyrazines, and related macrocycles as ligands have been most intensively investigated. Because several reviews summarize preparations and properties (conductivity, photoconductivity, NLO, electroluminescent detectors) of these materials, only a short overview on these polymers is given [1,3,34,40,375-377]. Several years ago, unsubstituted macrocycles were employed as ligands. These polymers are much less soluble. Recently, the use of substituted macrocycles has led to soluble polymers which are analytically easier to characterize. 

P. Delannoy, Dark conductivity, photoconductivity and photovolatic conversion in organic molecular solids. Mater. Sci., 1981, 7, 13. 

A compilation of publications concerning conductivity, photoconductivity, thermopower. Hall-effect and rectifying effects in polyacetylene is shown in Fig. 17j but by no means this list can claim completeness. 

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