Hopping photoconductivity in an exponential density of states

Photoconductivity in organic semiconductors is modeled taking into account the hopping nature of charge transport in an exponential density of states and exploiting the transport energy concept. Explicit and analytical expressions describing device behavior are obtained, and a robust procedure is outlined to extract from experimental measurements relevant material parameters, including the charge density dependent bulk mobility, as we show on a prototypical all-organic photoconductor. This qualifies the photoconductor not only as a technologically relevant device but also as a test bed for the optoelectronic characterization of disordered materials. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4750239]