Multiexciton Dynamics Depending on Intramolecular Orientations in Pentacene Dimers: Recombination and Dissociation of Correlated Triplet Pairs.
J Phys Chem Lett
; 9(12): 3354-3360, 2018 Jun 21.
Article
in En
| MEDLINE
| ID: mdl-29847939
ABSTRACT
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.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
J Phys Chem Lett
Year:
2018
Document type:
Article
Affiliation country:
Japón