Xerographic discharge in insulators with Poole-Frenkel drift mobility

In the search for new materials useful in electrophotography, it has been recognized that there are photoconducting insulators whose charge transport properties are governed by a drift mobility that is not constant, but varies with electric field. The most prominent of these materials is the organic polymer poly-N-vinyl-carbazole (PVK)
¹
and its complexes with organic electron acceptors such as 2, 4, 7-trinitro-9-fluorenone (TNF).
²
Further, there is increasing evidence that the drift mobility in materials as varied as polyethylene
³
and Ge(Li)
⁴
depends on electric field.