TY - JOUR
T1 - Dynamics of the triplet-pair state reveals the likely coexistence of coherent and incoherent singlet fission in crystalline hexacene
AU - Monahan, Nicholas R.
AU - Sun, Dezheng
AU - Tamura, Hiroyuki
AU - Williams, Kristopher W.
AU - Xu, Bolei
AU - Zhong, Yu
AU - Kumar, Bharat
AU - Nuckolls, Colin
AU - Harutyunyan, Avetik R.
AU - Chen, Gugang
AU - Dai, Hai Lung
AU - Beljonne, David
AU - Rao, Yi
AU - Zhu, X. Y.
N1 - Publisher Copyright:
© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2017/4/1
Y1 - 2017/4/1
N2 - The absorption of a photon usually creates a singlet exciton (S1) in molecular systems, but in some cases S1 may split into two triplets (2×T1) in a process called singlet fission. Singlet fission is believed to proceed through the correlated triplet-pair 1(TT) state. Here, we probe the 1(TT) state in crystalline hexacene using time-resolved photoemission and transient absorption spectroscopies. We find a distinctive 1(TT) state, which decays to 2×T1 with a time constant of 270 fs. However, the decay of S1 and the formation of 1(TT) occur on different timescales of 180 fs and <50 fs, respectively. Theoretical analysis suggests that, in addition to an incoherent S1 → 1(TT) rate process responsible for the 180 fs timescale, S1 may couple coherently to a vibronically excited 1(TT) on ultrafast timescales (<50 fs). The coexistence of coherent and incoherent singlet fission may also reconcile different experimental observations in other acenes.
AB - The absorption of a photon usually creates a singlet exciton (S1) in molecular systems, but in some cases S1 may split into two triplets (2×T1) in a process called singlet fission. Singlet fission is believed to proceed through the correlated triplet-pair 1(TT) state. Here, we probe the 1(TT) state in crystalline hexacene using time-resolved photoemission and transient absorption spectroscopies. We find a distinctive 1(TT) state, which decays to 2×T1 with a time constant of 270 fs. However, the decay of S1 and the formation of 1(TT) occur on different timescales of 180 fs and <50 fs, respectively. Theoretical analysis suggests that, in addition to an incoherent S1 → 1(TT) rate process responsible for the 180 fs timescale, S1 may couple coherently to a vibronically excited 1(TT) on ultrafast timescales (<50 fs). The coexistence of coherent and incoherent singlet fission may also reconcile different experimental observations in other acenes.
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U2 - 10.1038/nchem.2665
DO - 10.1038/nchem.2665
M3 - Article
AN - SCOPUS:85016332405
VL - 9
SP - 341
EP - 346
JO - Nature Chemistry
JF - Nature Chemistry
SN - 1755-4330
IS - 4
ER -