Photoconductor fatigue. 4. Effect of p-(diethylamino)benzaldehyde diphenylhydrazone derivatives on the photooxidation of the charge-transport layer of organic layered photoconductors

The photooxidation of the hole-transport molecule p-(diethylamino)benzaldehyde diphenylhydrazone (DEH) gives rise to residual surface charges during light decay which cannot be photodischarged fast enough for electrophotographic applications. The“electrical fatigue” is attributed to a photochemically induced unimolecular rearrangement of DEH to an indazole derivative. By appropriate substitution of the DEH derivative, the photocyclization reaction and therefore the associated electrical fatigue in the corresponding organic photoconductor are eliminated. These results establish a clear relationship between photochemistry and electrical fatigue. Electrochemical and electrophotographic studies reveal that the hole-transport properties of the DEH derivatives remain the same as DEH despite the structural modifications. Additionally, an X-ray crystal structure analysis of a novel DEH derivative, OMDEH, is reported. © 1992, American Chemical Society. All rights reserved.