TY  - JOUR
A1  - Vollbrecht, Joachim
A1  - Brus, Viktor V.
T1  - On the recombination order of surface recombination under open circuit conditions
JF  - Organic electronics : physics, materials and applications
N2  - 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 CH3NH3PbI3 pemvskite 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.
KW  - surface recombination
KW  - recombination order
KW  - organic photovoltaics
KW  - Perovskite solar cells
KW  - charge carrier density
KW  - Shockley-Read-Hall
KW  - statistics
Y1  - 2020
U6  - https://doi.org/10.1016/j.orgel.2020.105905
SN  - 1566-1199
SN  - 1878-5530
VL  - 86
PB  - Elsevier Science
CY  - Amsterdam [u.a.]
ER  - 
TY  - JOUR
A1  - Vollbrecht, Joachim
A1  - Brus, Viktor V.
T1  - Effects of recombination order on open-circuit voltage decay measurements of organic and perovskite solar cells
JF  - Energies : open-access journal of related scientific research, technology development and studies in policy and management / Molecular Diversity Preservation International (MDPI)
N2  - Non-geminate recombination, as one of the most relevant loss mechanisms in organic and perovskite solar cells, deserves special attention in research efforts to further increase device performance. It can be subdivided into first, second, and third order processes, which can be elucidated by the effects that they have on the time-dependent open-circuit voltage decay. In this study, analytical expressions for the open-circuit voltage decay exhibiting one of the aforementioned recombination mechanisms were derived. It was possible to support the analytical models with experimental examples of three different solar cells, each of them dominated either by first (PBDBT:CETIC-4F), second (PM6:Y6), or third (irradiated CH3NH3PbI3) order recombination. Furthermore, a simple approach to estimate the dominant recombination process was also introduced and tested on these examples. Moreover, limitations of the analytical models and the measurement technique itself were discussed.
KW  - organic solar cells
KW  - perovskite solar cells
KW  - non-geminate recombination
KW  - recombination order
KW  - open-circuit voltage decay
Y1  - 2021
U6  - https://doi.org/10.3390/en14164800
SN  - 1996-1073
VL  - 14
IS  - 16
PB  - MDPI
CY  - Basel
ER  -