Influence of bimolecular recombination on the photogeneration yield values determined by xerographic method

Xerographic method consists in monitoring of decay of the surface potential of the photoconducting layer under illumination. The charge carrier photogeneration quantum yield is determined basing on the initial potential decay rate. In this work the photogeneration quantum yield for theoretically simulated initial surface potential decay is analyzed for a case when simultaneous photogeneration and recombination occur. A model disordered organic photoconductor is considered in which the photogeneration probability is described by the Onsager model of geminate recombination and the cross-section for recombination exhibits power dependence on the electric field. Photogeneration yields calculated in the classical way and the yields calculated with assumed bimolecular recombination are compared. It is shown that for high bimolecular recombination probability correctly determining the classical xerographic method of photogeneration quantum yield is difficult.