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# Realistic Efficiency Limits for Singlet-Fission Silicon Solar Cells

journal contribution

posted on 2021-07-20, 18:36 authored by Benjamin Daiber, Koen van den Hoven, Moritz H. Futscher, Bruno EhrlerSinglet fission is
a carrier multiplication mechanism
that could make silicon solar cells much more
efficient. The singlet-fission process splits one high-energy spin-singlet
exciton into two lower-energy spin-triplet excitons. We calculated
the efficiency potential of three technologically relevant singlet-fission
silicon solar cell implementations. We assume realistic but optimistic
parameters for the singlet-fission material and investigate the effect
of singlet energy and entropic gain. If the transfer of triplet excitons
occurs via charge transfer, the maximum efficiency is 34.6% at a surprisingly
small singlet energy of 1.85 eV. For the Dexter-type triplet energy
transfer, the maximum efficiency is 32.9% at a singlet energy of 2.15
eV. For Förster resonance energy transfer (FRET), the triplet
excitons are first transferred into a quantum dot, from which they
then undergo FRET into silicon. For this transfer mechanism, the maximum
efficiency is 28.% at a singlet energy of 2.33 eV. We show that the
efficiency gain from singlet fission is larger the more efficient
the silicon base cell is, which stands in contrast to tandem perovskite–silicon
solar cells.