Analysis of the image force effects on the recombination at the donor–acceptor interface in organic bulk heterojunction solar cells

We consider the influence of image force effects on the recombination at the donor–acceptor interface in organic bulk heterojunction solar cells. The conclusion is that the charge carriers of one sign located in the material with lower permittivity recombine at the boundary between donor and acceptor phases. This process competes with the recombination of opposite sign charge carriers, leading to the reduction of the Langevin-type bimolecular recombination. The presented model is capable to explain the observed discrepancies between the experimental and Langevin recombination coefficients in the P3HT:PCBM blend.