TY - JOUR
T1 - Multiexciton Dynamics Depending on Intramolecular Orientations in Pentacene Dimers
T2 - Recombination and Dissociation of Correlated Triplet Pairs
AU - Sakai, Hayato
AU - Inaya, Ryutaro
AU - Nagashima, Hiroki
AU - Nakamura, Shunta
AU - Kobori, Yasuhiro
AU - Tkachenko, Nikolai V.
AU - Hasobe, Taku
N1 - Funding Information:
This work was partially supported by JSPS KAKENHI Grant Numbers No. 18H01957, 16K14067, 17H05270, and 17H05162 to T.H. and No. 17K14476 and 17H05381 to H.S. This work was performed under the Cooperative Research Program of the “Network Joint Research Centre for Materials and Devices”. We are grateful to Dr. Tatsuo Nakagawa and Mr. Hiroaki Hanada (Unisoku Co., Ltd.) for picosecond transient absorption measurements by the Randomly Interleaved Pulse Train Method. The work at Kobe University was supported by a Grant-in-Aid for Scientific Research (No. 17K19105 and 16H04097 to Y.K. and 17J01125 to H.N.) from the Ministry of Education, Culture, Sports, Science and Technology, Japan. Pulsed EPR experiments were supported by the Nanotechnology Platform Program (Molecule and Material Synthesis). This work was carried out by the joint research program of Molecular Photoscience Research Center, Kobe University.
Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/6/21
Y1 - 2018/6/21
N2 - Pentacene dimers bridged by a phenylene at ortho and meta positions [denoted as o-(Pc)2 and m-(Pc)2] were synthesized to examine intramolecular orientation-dependent multiexciton dynamics, especially focusing on singlet fission (SF) and recombination from correlated triplet pairs [(TT)]. Absorption and electrochemical measurements indicated strong intramolecular couplings of o-(Pc)2 relative to m-(Pc)2. Femtosecond and nanosecond TA measurements successfully demonstrated efficient SF in both dimers. In contrast, the dissociation process from the (TT) to the individual triplets [(2 × T)] was clearly observed in m-(Pc)2, which is in sharp contrast to a major recombination process in o-(Pc)2. Time-resolved electron spin resonance (TR-ESR) measurements demonstrated that the recombination and dissociation proceed from the quintet state of 5(TT) in m-(Pc)2. The rate constant of the SF was 2 orders of magnitude greater in o-(Pc)2 than that in m-(Pc)2 and was rationalized by enhanced electronic coupling between adjacent HOMOs of the Pc units.
AB - Pentacene dimers bridged by a phenylene at ortho and meta positions [denoted as o-(Pc)2 and m-(Pc)2] were synthesized to examine intramolecular orientation-dependent multiexciton dynamics, especially focusing on singlet fission (SF) and recombination from correlated triplet pairs [(TT)]. Absorption and electrochemical measurements indicated strong intramolecular couplings of o-(Pc)2 relative to m-(Pc)2. Femtosecond and nanosecond TA measurements successfully demonstrated efficient SF in both dimers. In contrast, the dissociation process from the (TT) to the individual triplets [(2 × T)] was clearly observed in m-(Pc)2, which is in sharp contrast to a major recombination process in o-(Pc)2. Time-resolved electron spin resonance (TR-ESR) measurements demonstrated that the recombination and dissociation proceed from the quintet state of 5(TT) in m-(Pc)2. The rate constant of the SF was 2 orders of magnitude greater in o-(Pc)2 than that in m-(Pc)2 and was rationalized by enhanced electronic coupling between adjacent HOMOs of the Pc units.
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U2 - 10.1021/acs.jpclett.8b01184
DO - 10.1021/acs.jpclett.8b01184
M3 - Article
C2 - 29847939
AN - SCOPUS:85048051622
SN - 1948-7185
VL - 9
SP - 3354
EP - 3360
JO - Journal of Physical Chemistry Letters
JF - Journal of Physical Chemistry Letters
IS - 12
ER -