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@ARTICLE{Classen:890081,
author = {Classen, Andrej and Chochos, Christos L. and Lüer, Larry
and Gregoriou, Vasilis G. and Wortmann, Jonas and Osvet,
Andres and Forberich, Karen and McCulloch, Iain and
Heumüller, Thomas and Brabec, Christoph J.},
title = {{T}he role of exciton lifetime for charge generation in
organic solar cells at negligible energy-level offsets},
journal = {Nature energy},
volume = {5},
number = {9},
issn = {2058-7546},
address = {London},
publisher = {Nature Publishing Group},
reportid = {FZJ-2021-00671},
pages = {711 - 719},
year = {2020},
abstract = {Organic solar cells utilize an energy-level offset to
generate free charge carriers. Although a very small
energy-level offset increases the open-circuit voltage, it
remains unclear how exactly charge generation is affected.
Here we investigate organic solar cell blends with highest
occupied molecular orbital energy-level offsets (∆EHOMO)
between the donor and acceptor that range from 0 to 300 meV.
We demonstrate that exciton quenching at a negligible
∆EHOMO takes place on timescales that approach the exciton
lifetime of the pristine materials, which drastically limits
the external quantum efficiency. We quantitatively describe
this finding via the Boltzmann stationary-state equilibrium
between charge-transfer states and excitons and further
reveal a long exciton lifetime to be decisive in maintaining
an efficient charge generation at a negligible ∆EHOMO.
Moreover, the Boltzmann equilibrium quantitatively describes
the major reduction in non-radiative voltage losses at a
very small ∆EHOMO. Ultimately, highly luminescent
near-infrared emitters with very long exciton lifetimes are
suggested to enable highly efficient organic solar cells.},
cin = {IEK-11},
ddc = {330},
cid = {I:(DE-Juel1)IEK-11-20140314},
pnm = {121 - Solar cells of the next generation (POF3-121)},
pid = {G:(DE-HGF)POF3-121},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000564493100001},
doi = {10.1038/s41560-020-00684-7},
url = {https://juser.fz-juelich.de/record/890081},
}