TY - JOUR
T1 - Endothermic singlet fission is hindered by excimer formation
AU - Dover, Cameron B.
AU - Gallaher, Joseph K.
AU - Frazer, Laszlo
AU - Tapping, Patrick C.
AU - Petty, Anthony J.
AU - Crossley, Maxwell J.
AU - Anthony, John E.
AU - Kee, Tak W.
AU - Schmidt, Timothy W.
N1 - Publisher Copyright:
© 2018 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
PY - 2018/3/1
Y1 - 2018/3/1
N2 - Singlet fission is a process whereby two triplet excitons can be produced from one photon, potentially increasing the efficiency of photovoltaic devices. Endothermic singlet fission is desired for a maximum energy-conversion efficiency, and such systems have been considered to form an excimer-like state with multiexcitonic character prior to the appearance of triplets. However, the role of the excimer as an intermediate has, until now, been unclear. Here we show, using 5,12-bis((triisopropylsilyl)ethynyl)tetracene in solution as a prototypical example, that, rather than acting as an intermediate, the excimer serves to trap excited states to the detriment of singlet-fission yield. We clearly demonstrate that singlet fission and its conjugate process, triplet-triplet annihilation, occur at a longer intermolecular distance than an excimer intermediate would impute. These results establish that an endothermic singlet-fission material must be designed to avoid excimer formation, thus allowing singlet fission to reach its full potential in enhancing photovoltaic energy conversion.
AB - Singlet fission is a process whereby two triplet excitons can be produced from one photon, potentially increasing the efficiency of photovoltaic devices. Endothermic singlet fission is desired for a maximum energy-conversion efficiency, and such systems have been considered to form an excimer-like state with multiexcitonic character prior to the appearance of triplets. However, the role of the excimer as an intermediate has, until now, been unclear. Here we show, using 5,12-bis((triisopropylsilyl)ethynyl)tetracene in solution as a prototypical example, that, rather than acting as an intermediate, the excimer serves to trap excited states to the detriment of singlet-fission yield. We clearly demonstrate that singlet fission and its conjugate process, triplet-triplet annihilation, occur at a longer intermolecular distance than an excimer intermediate would impute. These results establish that an endothermic singlet-fission material must be designed to avoid excimer formation, thus allowing singlet fission to reach its full potential in enhancing photovoltaic energy conversion.
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U2 - 10.1038/nchem.2926
DO - 10.1038/nchem.2926
M3 - Article
C2 - 29461531
AN - SCOPUS:85042223324
SN - 1755-4330
VL - 10
SP - 305
EP - 310
JO - Nature Chemistry
JF - Nature Chemistry
IS - 3
ER -
