On the applicability of Schottky diffusion theory to non-ohmic cathode contact P3HT:PCBM bulk-hetero junction solar cell

The classical Schottky diffusion theory is applied to a non-ohmic cathode contact P3HT:PCBM bulk-heterojunction solar cell under the assumption of a p-type doped active region. Analytical expressions of the dark current density/voltage (JD/V) characteristic and the open-circuit voltage under illumination VOC are, thus, derived for this cell. They are validated with reference to a complete numerical simulation by the analysis of microelectronic and photonic structures-one-dimensional simulator. The Schottky diffusion theory is shown to be reasonably applicable to modeling the JD/V characteristic in the forward bias region within the range below the built-in voltage Vbi and in the complete reverse bias region. It is demonstrated that depending on the p-doping density NA and the hole mobility μh of the active region, VOC is linearly controlled by the Schottky barrier height φB.