Electrophotographic methods

The photosensitivity and its increase after ultraviolet illumination was confirmed by electrophotographic methods for polymers with triple bonds... 

The electrophotographic method requires a process of forming an electrostatic latent image on a photoreceptor drum by charging and light exposure. Therefore, the system becomes complicated, resulting in increased costs of production (21). 

The photoconductivity of layers obtained by suspending a variety of benzothiazole derivatives in cyclohexanone-formaldehyde resin or poly-iV-vinylcarbazole has been determined by electrophotographic methods, and various factors that exert an influence on this property have been studied. The photoconductivity, S (lx s ), of the best examples ranges between 0.1 x 10 and 0.5 x 10 these are suitable in the production of xerographic images. ... 

A. B. Dravin and Zh. V. Kirillova, Preparation of Offset Prints by the Electrophotographic Method, Izd. VNIIPP (1962) collection Electrophotography and Magnetography, Vilna (1965), p. 135. 

The detection of spectral sensitizing action often depends on amplification methods such as photographic or electrophotographic development or, alternatively, on chemical or biochemical detection of reaction products. Separation of the photosensitization reaction from the detection step or the chemical reaction allows selection of the most effective spectral sensitizers. Prime considerations for spectral sensitizing dyes include the range of wavelengths needed for sensitization and the absolute efficiency of the spectrally sensitized process. Because both sensitization wavelength and efficiency are important, optimum sensitizers vary considerably in their stmctures and properties. 

Electrical Conductivity. Changes in the electrical conductivity within or on the surface of a photopolymer film can be used to visualize the results of a photochemical reaction. A limited number of electrophotographic/electrostatic processes have been developed employing this readout method (22). 

Mobility measurements by the TOP methods considered in Chapters 3 and 4 are particularly important, but they cannot give information about the whole spectrum of states in the mobility gap of amorphous chalcogenides. Therefore, in addition to TOP, XTOP, IPTOP, TSC, and TSDC, other complimentary techniques that probe the gap states are needed. Xerographic techniques that were initially developed to characterize properties of electrophotographic (xerographic) receptors [1] seemed to be informative, suitable, and widely applicable for the study of amorphous thin films and photoconductive insulator thin films [2],... 

Identical methods for investigation of photoconductivity can be used for inorganic and organic semiconductors. Polymer semiconductors as a rule have very high resistance. For such materials the main information about the photoconductive mechanisms and properties may be obtained by two methods electrophotographic (or discharge method) and time of flight (or transit method). Both methods are successfully applied for materials with low mobilities, less than lO-4m2 V-1 s-1, which are the usual values for polymer semiconductors. 

Fig, la, b. Typical schemes of the electrophotographic (a) and time of flight (b) methods for photoconductivity measurements in polymers [11]... 

Purification. The purity of the polymer has a decisive influence on various electrophotographic characteristics, such as photoconductivity and photosensitivity. A content of less than 100 ppm is required with respect to the monomer. Regardless of the method of preparation, the polymer is contaminated with up to 6% of NVK, up to 500 ppm carbazole, anthracene, and with sulfur compounds in the ppm range [25]. 

---