Poly photoconductor

PBO polymers, 13 377. See also Poly(p-phenylene benzobisoxazole) (PBO) applications of, 13 379 degradation of, 13 379 early syntheses of, 13 378 PB resin, properties of, 20 419t PbSe photoconductors, 19 157 PbS photoconductors, 19 157 PBT molding resins, 20 62-64. See also Poly(butyleneterephthalate) (PBT) PBT polymer... 

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. 

There seems no doubt that organic photoconductor systems will permit the development of new reproduction processes based on the electrophotographic principle 10>. Dyes play an important role in this development on the one hand they act as spectral sensitizers of the organic photoconductors (e.g. poly-N-vinyl-carbazole 161> and on the other hand, the photoelectric effects of dyes are important for... 

Polymers with saturated bonds, heteroatoms, heterostructures and poly-conjugated ones are available now as photosensitive materials. Really one cannot expect a single mechanism to be reponsible for photoconductivity in so many diverse systems. However, there are a lot of verified factors which permit us to explain the main features of the photoconductive processes in polymers. The status and prospects of the application of polymeric photoconductors as prospective new electronic materials will be also analyzed for various types of photoconductors. 

The earliest all-organic photoconductive compositions consisted of poly-vinyl(carbazole) (PVK, 1) and 2,4,7-trinitrofluorenone (TNF, 2) [25], In spite of its historical importance, the PVK/TNF system is an unusual one, because it is one of the few photoconductors which acts simultaneously as a photogenerator of primary charges and the medium in which the charge transport is accomplished. It is much more usual to employ a separate charge generator and a distinct transport medium. 

Kanemitsu et al. (1989) observed decreased charge acceptance after prolonged irradiation of polymers doped with the hole transport molecule 2-(p-dipropylaminophenyl) -4- (p-dimethylaminophenyl) -5- (o-chlorophenyl) -1,3-oxazole. The effects depended on the polymer. A mechanism involving photo-induced charge transfer was proposed. Stolle et al. (1987) made a similar observation in studies of polymer photoconductors such as poly(N-vinyl-... 

Yagishita, T., Ikegami, K., Narusawa, T. and Okuyama, H. (1984). Photoconduction of copper phthalocyanine-binder photoconductor sensitized with poly-A-vinylcarbazole. IEEE Trans. Ind. Appl, IA-20, 1642-6. [207]... 

P35 as photoconductors was also investigated in a single-layer device.67 A recent study also showed that polymer P35 displays a large optical-limiting response to a nanosecond laser pulse with satisfactory threshold value at 0.12J/cm2, and its behavior is superior to that for poly(4,4 -diethynyl-5,5 -bithiazole) organic polymer.60... 

Carbazole is vinylated in the 9-position by acetylene. The resulting polymer 5 (poly-A -vinylcarbazole) proves to be a photoconductor ... 

Much work has been reported on the development of carbazole derivatives and also noncarbazole photoconductive polymers. An example of the latter group is poly(bis(2-naphthoxy)phosphazene), which is intrinsically an insulator with a very low photosensitivity toward both UV and visible radiation, but when doped with trinitrofiuorenone in a 1 1 molar ratio, it is a strong photoconductor. 

It should be pointed out that a specific modification of Ti(0)Pc 1 (R = -H) in organic polymers is the most widely used photoconductor in bilayer photoreceptor copiers and laser printers [19]. A thin film containing ethylene-bridged silicon phthalocyanine polymer dispersed in poly(vinylidene fluoride) (1 4 by weight) obtained by casting from a DMF slurry on quartz was orientated in an electrical field [20], A double-layered receptor device for measuring the... 

P. Pistor, V. Chu, D. M. F. Prazeres, and J. P. Conde. pH sensitive photoconductor based on poly(para-phenylene-vinylene). Sens. Actuators, B, 123(1) 153-157, April 2007. 

As regards photoconducting polymers, typical work has been carried out with poly(N-vinylcarbazole), PVK, and polysilylenes. The first commercial photoconductor was based on a 1 1 charge-transfer (CT) complex between PVK and trini-trofluorenone (TNF) [11]. Similar photoconductor properties were found with a 1 1 CT complex of TNF with poly[bis(2-naphthoxy)phosphazene] (see Chart 2.7), which is an insulator if dopant-free [54]. 

The optical transparency of poly(vinyl carbazole) films produced by this room temperature process appears to be quite high, although transparency decreases at high conversions. In film form, this material is useful for photoconductors, charge-transfer complexes, and electroluminescent devices. The higher polymer molecular weight typically enhances film mechanical properties [247]. 

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