Electrophotographic properties of H₂·Pc (metal-free phthalocyanine) -PVK (poly-N-vinylcarbazole) multilayered photoreceptors were investigated. The negative charge acceptance decreased with the thickness of H₂·Pc layer. Purification of H₂·Pc before the vacuum deposition with hot water and tetrahydrofuran improved the charge acceptance. The dark decay, the xerographic gain and the residual voltage were examined as a function of the thickness of H₂·Pc layer and the purification of its source. The results were discussed in terms of space charges in the H₂·Pc layer that are affected by the interaction between the H₂·Pc and PVK layers, as well as the thermal carrier density of the H₂·Pc layer. Photoinjection of holes from the H₂·Pc into PVK layers also modifies the space charge distribution, and its relaxation is faster when the conductivity of H₂·Pc layer is higher.
The hole photoinjection from the H₂·Pc layer into the PVK layer by means of the transient photocurrent technique was revealed that the injection field at the H₂·Pc-PVK interface is higher with high resistivity H₂·Pc layers. This result is consistent with the space charge consideration above discussed.

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A new type of monocomponent magnetic toners for electrophotography was manufactured. These toners have resistivity of as high as 10¹⁴Ω·cm and can accept triboelectric charge. Dye charge control agents are employed to determine the sign and quantity of triboelectric charge on toner particles.
Development characteristics, transfer efficiency and charging properties of these toners were compared with those of conductive magnetic toners and high-resistivity magnetic toners. Newly manufactured triboelectric magnetic toners have very high toner deposition mass of 2 mg/cm² when the value for surface potential of the recocding layer is 500 V. Transfer efficiency of these toners to plain paper is large as 80%. Charge of triboelectric toner does not depend upon the developing conditions are varied, while that of conductive toner and high-resistivity toner changes according to developing conditions. In the experiment, the toner charge to mass ratio of the positively charged toner was 4.2μ C/g and that of the negatively charged toner was -3.5μ C/g.

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Carrier transport properties of copper-phthalocyanine pigment uniformly dispersed in poly (N-vinyl carbazole) matrix are investigated. The electrophotographic layer containing a low concentration, 2∼5 % wt of phthalocyanine in PVK binder shows a high photosensitivity under the positive corona charging. It is considered that there is a long separation from a phthalocyanine particle to another in PVK containing 0.5 to 2 weight percent of pigment. This means that the photoholes can be injected from phthalocyanine to PVK layer and transported through the PVK bulk. The saturated surface potential is 450 V and the half decay energy is 28 erg/cm² at 650 nm wavelength in CuPc-PVK photoreceptor containing 2 weight percent of CuPc pigment.
From measurements of the drift mobility using the time of flight technique, it is understood that the role of phthalocyanine pigment is to increase the effective drift mobility and trap for holes in PVK.

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Electrophotographic properties of new benzopyrylium salts as a sensitizer for PVK derivatives have been studied. These sensitizers were synthesized by the reaction of some benzopyrylium salts with their colorless leuco-bases.
Thus we found that the new benzopyrylium salts have the spectral response in longer wavelength region than the original benzopyrylium salts used for the reaction and are effective for enhancing the sensitivity of PVK or brominated PVK. We could not make clear the chemical structure of the product obtained by the reaction of a benzopyrylium salt with a leuco-base. However, it may be assumed that some substitution reaction to shift the λ_max to longer wavelength region by a new conjugated system has occured.

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Both electrical characteristics and photovoltaic effect were investigated on the compressed γ–In₂Se₃ powder. Additive effect of poly (vinylidene fluoride) to the system was also studied.
The current transport was thermionic process and photovoltaic effect was improved by the addition of PVDF to the amount of 0.1ω_i, %. Different activation energies were observed in different air pressure. While, the sample with PVDF had the only activation energy larger than those of sample without PVDF. Capacitance increased as the bias voltage increased in spite of its polarity. The fact was attributed to the back contact double Schottky barrier with inversion layer.

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