Layered photoconductive element

Claim 1

In a photoconductive element comprising an electrically conductive, supporting substrate and a photoconductive layer carried by said substrate wherein a blocking layer means is carried adjacent at least one major surface of said photoconductor layer to suppress the flow of charge carriers attracted toward the photoconductive layer as a result of any surface charge applied to said element, wherein the improvement comprises a space charge layer interposed between said blocking layer means and said photoconductive layer, said space charge layer comprising a semiconductive material selected from the group consisting of n-type and p-type semiconductor materials, the space charge layer between said photoconductive layer and said blocking layer being selected so that upon charging said photoconductive element the electrical field at the interface between said space charge layer and said photoconductor is higher than the electric field at the interface between said space charge layer and said blocking layer.