On the recombination order of surface recombination under open circuit conditions.

Understanding the recombination dynamics of organic and perovskite solar cells has been a crucial prerequisite in the steadily increasing performance of these promising new types of photovoltaics. Surface recombination in particular has turned out to be one of the last remaining roadblocks, which specifically reduces the open circuit voltage. In this study, the relationship between the rate of surface recombination and the density of charge carriers is analyzed, revealing a cubic dependence between these two parameters. This hypothesis is then tested and verified with the recombination dynamics of an organic solar cell known to exhibit significant surface recombination and a high energy proton irradiated CH 3 NH 3 PbI 3 perovskite solar cell during white light illumination. Incidentally, these results can also explain recombination orders exceeding the commonly known threshold for bimolecular recombination that have been observed in some studies without the need for a charge carrier dependent bimolecular recombination coefficient. Image 1 • Surface recombination specifically reduces the open circuit voltage in organic and perovskite solar cells. • A cubic relationship between the rate of surface recombination and the charge carrier density has been derived. • This hypothesis has been successfully tested for organic and perovskite solar cells. • Recombination orders β > 2 can now be explained without charge carrier density dependent k bm. [ABSTRACT FROM AUTHOR]