Yasushi Hishiki

Preparation and properties of polyoxazoles

Polyoxazoles were prepared by the polycondensation of 2,6-diaminophenylene p-benzbisoxazole as monomer with terephthalaldehyde, isophthalaldehyde, glyoxal, tetrachloro-p-benzoquinone, terephthaloyl chloride, isophthaloyl chloride and p-xylylene dibromide in various polar solvents. Infra-red spectra, visible spectra and elemental analyses support the presence of an oxazole ring in a main polymer chain. Specific resistivities were in the range 1012–1014ohmcm at room temperature. The value of the energy gap was 0.3–3.1eV. A link was observed in the temperature dependence curve of specific resistivity. These polymers are insoluble in organic solvents and they were found to be extremely thermally stable under oxidative conditions up to about 400°C.

Supersensitization for dye-sensitized CdS by the combinations of two dyes

AbstractThis investigation is concerned with a supersensitization phen~menon for CdS sensitized by the combinations of two dyes. As experimental results, the photoconductivity could be supersensitized by dye combinations. But the essential photoconductive sensitivity has decreased its value compared with the case of dye-sensitized CdS which adsorbed single dye on CdS surface.We conclude that the desensitization of photoconductive sensitivity can be caused by the increase of shallow trapping levels and the darkcurrent owing to injecting electrons thermally from the number of shallow trap depths to conduction band of CdS.

Photoconductive Sensitivity and Trap Depths of the Sublimated Dye Films

AbstractThis investigation is concerned with a photoconductive sensitivity and the trap depths for sublimated dye films (SDF) in the spectral sensitization process. We have observed the photoconductive sensitivity (Ip/Id in the range of 0.5-0.02 for SDK in a vacuum by their absorption of light. In addition, traps were observed for all types of sensitizing and desensitizing dyes.We conclude that a small photoconductive sensitivity exists in these dyes and that several types of traps are associated with the spectral sensitization process. It would be expected to get a large photoconductive amplification since a large number of carriers are injected from the excited stale of solid slate dye into the conduction hand of photoconductor.