Photoconductive polymers materials

Photoconductive polymers are widely used in the imaging industry as either photosensitive receptors or carrier (electron or hole) transporting materials in copy machines and laser printers. This is still the only area in which the photoelectronic properties of polymers are exploited on a large-scale industrial basis. It is also one electronic appHcation where polymers are superior to inorganic semiconductors. 

The most important industrial appHcation of photoconductive polymers is electrophotography (qv). This is a biUion doUar industry and one of the few electronic areas where polymeric material excels. The principles and practices of electrophotography have been reviewed in detail elsewhere (9,85) and are not repeated here. 

Various types of the photoconductive polymers are available now. The photoconductivity of such materials may be essentially increased by means of the chemical and spectral sensitization [12-14]. Spectral sensitization is connected with the appearance of the photosensitivity in the new spectral bands and the chemical sensitization with the increase of the proper sensitivity. As a rule both types of sensitisation may take place in the photoconductor at the same turn. The first data about chemical and spectral sensitization in organic photoconductors appeared in [19, 20]. The example of the chemical and spectral sensitization of the photoconductivity by dyes in polymeric copper-phenyl-acetylenide is presented in Fig. 2. Later on it was proposed that not only low molecular weight compounds but polyconjugated polymers could also be used as sensitizers [21] having broad absorption tends and high thermostability compared with dyes. Now it is clear that various types of molecules may be used as a photosensitizers. 

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]. 

A number of reviews have appeared of topical interest. These include photoisomerism of azo dyes, ° photofunctional polysilanes,photochromic pigments, rare earth complexes, pressure sensitive paints, electron-transfer processes,electroactive dendrimers, chiral polyisocyanates, photodefin-able benzocyclobutene, photoconductive polymers,excited states in conjugated polyenes, photosensitive materials and polyazomethanes. ... 

D. Haarer, Photoconductive Polymers A Comparison with Inorganic Materials, Adv. Solid State Phys. 30 (1990) 157. 

Kwon OP, Lee SH, Montemezzani G, Gunter P. Layer-structured photoconducting polymers a new class of photorefractive materials. Adv Funct Mater 2003 13(6) 434-8. 

Photoconductive -k9n- k9k-tiv (1929) adj. Becoming electrically conductive when irradiated by light or ultraviolet light. Emerson JA, Torkelson JM (eds) (1991) Optical and electrical properties of polymers materials research society symposium proceedings, vol 24. Materials Research Society, Warrendale, PA. 

Since 1992 when the first edition of the Handbook of Polymer Synthesis was published a number of new applications for photoconductive polymers or, to put it correct, charge transport materials, have appeared. The most successful development are organic light emitting diodes (OLEDs) whieh right now enter the market as bright displays for cellular phones and ear radios. Other imortant areas are organie field effect transistors, solar cells and lasers. 

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