Photoconductors electrophotography

Coloured materials find application in both toners and organic photoconductors fused in electrophotography. Photoconductors will be covered in detail in Chapter 4 (section 4.4) and only toner resins will be considered in this section. 

Laser printers and photocopiers use electricity and light to produce an image, hence the name electrophotography. The two main components are the photoconductor, now invariably an... 

Poly-N-vinylcarbazole is one of the very important organic photoconductors now in use in electrophotography. For practical use, a little amount of sensitizer is usually added. 

Polymers with triple bonds have been applied in electrophotography [176] and were the first among organic photoconductors with sensitized by dyes photoconductivity [19,20]. 

As already shown, the sensitized spectra follow the dye absorption. Most of the dyes have sufficiently narrow absorption bands. This does not permit us to obtain the panchromatic sensitivity in the sufficiently broad spectral range. It was proposed to use the polymers with conjugated bonds as sensitizers [21]. The broad diffuse absorption spectra are inherent to such compounds. One can expect higher thermal stability from such sensitizers. In addition the application of binder may be omitted from the preparation of the photosensitive layers, for example, in electrophotography. Polymers with triple bonds, polyphenylenes and polyoxiphenylenes were used as sensitizers [10, 14, 278-280]. The typical results are shown in Fig. 47. The main rules for photoconductivity sensitized by polymers were the same as for the dyes. Optimum sensitization was obtained at the concentration of the sensitizer of 10 1-10-2 g/cm3 relative to the polymeric photoconductor weight. 

Nowadays, polymeric photoconductors may be used in electrophotography, microfilms, photothermoplastic recording, spatial light modulators, and nonlinear elements. The combination of photosensitivity with high quality electrical and mechanical properties permits the use of such materials in optoelectronics, holography, laser recording and information processes. The applications of the various types of polymers were reported in the final parts of the relevant items in the earlier sections. Here, we will briefly analyze the common features of photoconductive polymer applications. The separate questions of each type have been dealt with in some books and papers [3, 11, 14, 329]. 

Dye bases of apocyanine dyes are also used as organic photoconductors in electrophotography [56],... 

This group of dyes is used in electrophotography to make organic photoconductors [68], In addition to the unsubstituted l,3,3-trimethyl-2-methyleneindo-line, the 5-chloro derivative is often used as the heterocyclic condensation component [69],... 

Table 3.3 Electrophotography and Organic Photoconductors The electrophotography process...

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