Photoreceptors, concepts

Most practical polymer-based electrophotographic photoreceptor systems now in use are in fact solid solutions of an active species in a binder host polymer 11). This system concept embodies the notion of full chemical control of the transport process. Thus, the concentration of dopant molecules directly controls the drift mobility, which is in turn controlled by the overlap of wave functions between active sites. The host polymer binder is then specialized for its mechanical and adhesive properties. Understanding the key features of small-molecule transport provides guidelines for the optimization of injected-carrier range. The key point is to understand how chemically induced traps arise in such systems and how molecularly doped materials containing various contaminants in substantial quantities can still efficiently transport charge. (Even part-per-million concentrations of con-... 

Single-layer photoreceptor devices have always been very attractive for economic reasons. The continuous improvement in the bilayer device technology, in terms of photoelectrical and mechanical properties, has made re-introduction of the single-layer concept difficult. However, single-layer devices may re-surface at the low end with today s improved materials and know-how. At the low end, providing the performance is adequate, cost is a big driver. 

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