The influence of the thickness, recombination and space charge on the loss of photocurrent in organic semiconductors: an analytical model

We propose an analytical model of the photocurrent efficiency dependence on the light intensity in organic semiconductors. The influence of the thickness of sample, space charge effects and recombination of charge on the loss of photocurrent has been considered. We demonstrate that the presented model is the enhancement of an analytical model reported recently by Rappaport et al ( 2005 J. Appl. Phys. 98 033714). The method to identify and separate regions where the role of bimolecular recombination or the space charge dominates in the photocurrent is presented. The developed model can be useful for the modelling of the loss photocurrent in organic photovoltaic cells.