Electron-Transporting Polyamides for Organic Photoreceptors

Negatively chargeable dual-layer organic photoreceptors (OPC) are typically prepared with an electrical (hole) blocking layer disposed between the conductive support and the charge-gene ration layer (CGL). The blocking layer provides an energy barrier to the injection of positive charges. In an electrophotographic charge/expose cycle, charge is generated in the CGL, and the OPC is discharged primarily by the transport of positive charge through the charge-transport layer to the negatively charged surface. Simultaneously, electrons in the CGL drift toward the grounded conductive layer. If the intervening blocking layer material is insulating, an undesirable residual charge will be produced. We have prepared hole-blocking layer polymers that transport electrons under an applied electric field. In these materials, naphthalene bisimide (NB) is the transport active moiety. This talk will discuss the synthesis and properties of high molecular weight polyamides with incorporated tetracarbonylbisimides. A desirable characteristic of such a blocking layer is that solvents used in the coating of subsequent layers do not attack it. These electron-transport active polyamides are soluble in mixed solvents, but are insoluble in chlorinated hydrocarbons or other solvents commonly used for coating other OPC layers. Because these blocking layers transport electronically, their function is substantially insensitive to humidity.