Modeling the electrical characteristics of P3HT:PCBM bulk heterojunction solar cells: Implementing the interface recombination

The interface recombination of charge carriers located in the material with lower permittivity (Szmytkowski 2009 Chem. Phys. Lett. 470 123) has been implemented for the first time to calculate the electrical characteristics of the donor-acceptor P3HT:PCBM bulk heterojunction solar cell. In order to estimate the photocurrent density in this system, a simple analytical formula has been derived. We have obtained a very good agreement between experimental results and theoretical calculations. It leads to conclusion that the major contribution to the recombination in the P3HT: PCBM blend is from the interface recombination with negligible contribution from the Langevin-type recombination. We suggest that the Braun-Onsager model, which is predominantly used to calculate the photogeneration efficiency at the donor-acceptor interface, cannot be used in the case when both materials in the blend are characterized by different permittivities.