Phenyl benzotriazole stabilized photosensitive device

#This invention relates in general to xerography and more specifically to a novel photosensitive device.

#In recent years, interest has been shown in flexible electrophotographic plates for use in high speed office copying machines. Some of these plates are multilayered devices comprising, a conductive substrate layer, an adhesive-blocking interface layer, a charge generation layer and a charge transport layer. The charge transport layer comprises an organic charge transport molecule dissolved in a polymeric matrix material. This layer is substantially nonabsorbing in the spectral region of intended use, i.e. visible light, but is "active" in that it allows (1) injection of photogenerated holes from the charge generation layer and (2) efficient transport of these charges to the surface of the transport layer to discharge a surface charge thereon.

#One class of hole transport molecules, N,N'-diphenyl-N,N'-bis(alkylphenyl)-[1,1'-biphenyl]-4,4'-diamines have been extensively studied as solutions or dispersions in polycarbonate polymers. The conductivity of this class of compounds in polycarbonate polymers has been found to increase under certain circumstances. As photoreceptor devices employing this class of compounds in the presence of a halogen-containing alkane solvent is subjected to ultraviolet radiation, a condition known as "cycle down" progressively develops as the device is cycled in the xerographic process. "Cycle down" refers to the progressive increase in conductivity of the transport layer and in a relatively short period of time the charge acceptance of the device deteriorates. Also, special precautions have to be taken with regard to the handling of the devices employing these compounds. They cannot be stored or left exposed to ambient room light for any length of time because fluorescent lamps employed in most buildings contain a UV component. This UV radiation causes devices left exposed to the room light to undergo gradual deterioration resulting in an increase in the conductivity of the transport layer.

#In general, the advantages of the invention will become apparent upon consideration of the following disclosure of the invention, especially when taken in conjunction with the accompanying drawing wherein:

#The FIGURE is a schematic illustration of one of the members of the instant invention which comprise a photoreceptor having a charge generation layer overcoated with a charge transport layer.

#Referring to the FIGURE, reference character 30 designates an imaging member which comprises a supporting substrate 11 having a charge generator layer 12 thereon. Substrate 11 is preferably comprised of any suitable conductive material. Typical conductors comprise aluminum, steel, nickel, brass or the like. The substrate may be rigid or flexible and of any convenient thickness. Typical substrates include flexible belts of sleeves, sheets, webs, plates, cylinders and drums. The substrate or support may also comprise a composite structure such as a thin conductive coating contained on a paper base; a plastic coated with a thin conductive layer such as aluminum, nickel or copper iodine; or glass coated with a thin conductive coating of chromium or tin oxide.

#In addition, if desired, an electrically insulating substrate may be used. In this case, an electric charge, equivalent to a conductive layer, may be placed upon the insulating member by double corona charging techniques well known or disclosed in the art. Other modifications using an insulating substrate or no substrate at all include placing the imaging member on a conductive backing member or plate in charging the surface while in contact with said backing member. Subsequent to imaging, the imaging member may then be stripped from the conductive backing.

#Generator layer 12 contains photoconductive particles dispersed randomly without orientation in binder 14.