It has been known that the polymeric binder played an important role in the ZnO-resin photo-receptor layer. Despite of the intensive investigations^1)-4), it remained some unclarified aspects associated with the affect of binder in this heterogeneous system such as charge acceptance, carrier generation and, especially, carrier transportation problem.
The present paper reported the results studied about the influence of a variety of organic polymeric binders on the electrophotographic properties of ZnO-resin photo-receptor layer. Within the framework of the charging characteristics, the resins used in this study were classified into four groups (A, B, C, D). It should be noted that the charging with corona of ZnO binded with poly N-vinylcarbazole (group A) was drastically inhibited due to their strong electronic interaction. In order to disperse the microcrystalline ZnO, the weak interaction (dipole-dipole) between ZnO and the resins was necessary at least. Poly styrene and its derivatives (group A) were also ruled out as the binding materials. Conspicuous space charge effects on the photo-discharging were observed in the photo-receptor binded with high insulating resins (group B) at high binder contents. The photo-receptors used the binders of group C (for example, poly γ-Methyl-L-Glutamate), on the other hand, were scarcely affected by the space charge, thus lending support the idea that the binders should play an important role in the carrier-transport process of the photo-receptors.

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The electric field and temperature dependences of dark and photo-currents in Se or As₂Se₂Te/poly-N-vinylcarbazole (PVK) systems have been measured. The photocurrent vs. time curves indicate that holes created in As₂Se₂Te encounter a barrier against injection into PVK due to an energetic mismatch of the respective valence band edges. Holes trans-ferred from a As₂Se₂Te layer are injected effectively into the PVK, by insertion of a thin Se layer (0.05 μm) between the As₂Se₂Te and the PVK layers. The injection of efficiency of them, however, is decreased by a energy barrier due to a mismatch of valence bands at the interface between the As₂Se₂Te and the Se layers.

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The present paper is the sequel to the report which appeared in the previous paper.
In this paper, we describe the structure and performance of newly designed electrometers which have more excellent response characterisstics than the previous one.
These meters are suitable for detailed analyses of condution mechanisms in electroophotographic films under light exposure.
Decay characteristics of surface potential of an amorphous Se film and ZnO-binder films were measured under steady light exposure or flash exposure. Results obtained were compared with each other as to the performance characteristics of these meters.
Furthermore, based on the analytical results of the decay experiment, it was shown that the light-induced potential decay phenomena involve very troublesome but important problems that have been left unsolved.

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