Photogeneration of charge carrier in the organic photoreceptor for electrophotography are studied on two type photoreceptor structures consisting of anthanthrone/Ag and anthanthrone/Cu -phthalocyanine heterojunction. N-type anthanthrone (AT) /Ag-base photoreceptor has Schottoky barrier at AT/Ag junction. The photoreceptor, which is positively or negatively coronacharged, respectively, does not exhibit the electrophotographic photoresponse in the case of the charged free surface excitation by actinic light of AT. When light is absorbed at the region of AT/Ag Schottoky barrier, the photodecay of surface potential of the corona charged photoreceptor are observed. It is suggested that the barrier field is responsible for the free carrier generation from excitons. The Schottoky barrier just acts as the charge generation layer of a double layered photoreceptor. At the double layered photoreceptor of AT (n-type) /Cu-phthalocyanine (p-type) /Al, AT layer acts as the window for Cu-phthalocyanine action spectra. The spectral range of electrophotographic response of this photoreceptor is covered by both action spectra of AT and Cu-Pc. The heterojunction of AT/Cu-Pc interface have both functions of corona charge holding and photocarrier generation.

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Derivatives of 2, 7-bis (2-hydroxy-3-phenylcarbamoylnaphthalene-l-ylazo) fluorenone have been synthesized as the charge generation material used in the electrophotographic layered photoreceptor, and the relation between their IR spectra and electrophotographic sensitivity has been studied.
From the analysis of IR spectra, it has been found that these derivatives have the ketohydrazone structure, and that the intermolecular hydrogen bonding is formed through the amides. The substituents of anilied ring have a great influence on the intermolecular hydrogen bonding, i. e., the hydrogen bonding becomes stronger as the electronegativity of the substituents is higher.
On the other hand, the clear correlation is recognized between on the electrophotographic sensitivity and Hammett's constant as the effect of substituents of anilide ring in the derivatives, the sensitivity being higher according to the increase of the electronegativity.
These results lead to a conclusion that the substituents of anilide ring in the derivatives are important in order to make the electrophotographic sensitivity most suitable.

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Based on the drift mobility measurements in polymer dispersions of a series of triphenylamine derivatives, a guiding concept has been proposed for developing the better charge transporting organic materials in the xerographic photoreceptor. For the molecular design, (i) intramolecular poly-functionality as a structural minimum unit of the hole, e.g., more N-phenyl groups in the triphenylamine derivatives, (ii) intramolecular mobilizability of the hole state among the units as a result of intramolecular resonance, and (iii) no formation of deep structural carrier trap such as dimer sites, are essential. A compound, N, N, N', N'-tetra (3-methylphenyl) -4, 4'-diaminostilbene which fulfills these requirements exhibited excellent drift mobility.

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The photoresponse of organic photoconductive particles was studied in the thin layered state arranged uniformly on Al substrate.
The dark-and photo-conductivities were discussed as a function of the particle size and numbers of layers. The photodecay of surface potential for the triboelectric charged particles depends on the polarity of the triboelectric charges and properties of the component materials. It was alike for the electrophotographic photoreceptors. When the both properties accorded, the good photoresponse was found. The particle-particle and particle-electrode contact affected the movement of photo-generated carrier in the thin layers.

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Materials for a photo-induced memory effect on charge-acceptance were investigated in
Polyvinylcarbazole (PVK) films and the film doped with triphenylmethane dyes on In₂O₃--SnO₂ (ITO) conductive substrate exhibited an outstanding memory effect.
The photo-and spectral sensitivities, sensitization procedure, stability and erase of the memory effect were demonstrated in the photoreceptor consisting of PVK, 3, 3'-di (N-ethylcarbazoyl) phenyl carbonium tetrafluoroborate, and polyester on the ITO substrate.
The photoreceptor showed a high photo-sensitivity at 630nm and successfully applied to He-Ne laser recording.

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The α-titanylphthalocyanine dispersed in resinous solution with a grinding system formed
microcrystals of high orientation.
The dispersion film showed strong absorption in the infrared region (λ_max=830 nm) same as the case of a vacuum deposition film followed by solvent treatment. Electrophotographic properties were measured of multilayered photoreceptors incorporationg α-TiOPc dispersed film as CGL and a hydrazone compound layer as CTL. The photoreceptor showed high sensitivity in the wavelengths of LED (E_1/2=0.54 μJ/cm² at 660 nm) and laser diode (E_1/2=0.36 μJ/cm² at 780 nm) and was suggested to have enough durability in use of those printers in according to performance in the tests for environmental conditions and cyclic stability.

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An imaging system based on hydrophobic organic layer formation on ferrous oxide (Fe₂O₃) semiconductor electrodes was studied.
Fe₂O₃ thin film semiconductor electrodes were prepared by two methods; i) thermal oxidizing treatment of pure iron plates, ii) spray pyrolysis of FeCl₃ on conducting plates. Both of the ferrous oxide samples prepared could be used as a photoanode in the photoelectrochemical imaging system.
After photoelectolysis of the Fe₂O₃ electrodes in electrolytic solutions containing an aromatic compound (o-toluidine), a hydrophobic organic layer was formed on the surface. This reaction brought about an image which was applicable to planographic printing system. Change in wettability of the electrode surface was observed at the wavelength shorter than 550 nm, which nearly corresponded to the band gap energy of Fe₂O₃. This spectral property of the photorecepter satisfies the use of the imaging system in a visible wavelength region.
Differences in photoelectrochemical or imaging characteristics between the two types of Fe₂O₃ electrodes were also discussed in the present report.

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The hydrogenated amorphous silicon (a-Si : H) films were prepared at different deposition rates between 1 and 16 μm/h by rf planar magnetron sputtering method with various Ar and H₂ gas mixing ratios. The deposition rates were controlled by rf power levels and substrate-target distances. The maximum magnetic fluxes of permanent magnets used for sputtering were 0.0225 T and 0.0425 T at the surface of the target.
The resistivity and hydrogen contents of a-Si : H films decrease monotonically as the deposition rate increases. But, films prepared in the high gas mixing ratio between 0.4 and 0.6 show high resistivity (5×10¹² Ω·cm) even though the deposition rate is 12 μm/h.
The maximum value of the electrophotographic sensitivity of a-Si : H films prepared at deposition rates between 1 and 12 μm/h is about 0.15m²/mJ in the visible wavelength range.

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