Solvent-Controlled Branching of Localized versus Delocalized Singlet Exciton States and Equilibration with Charge Transfer in a Structurally Well-Defined Tetracene Dimer
A detailed photophysical picture is elaborated for a structurally well-defined and symmetrical bis-tetracene dimer in solution. The molecule was designed for interrogation of the initial photophysical steps (S 1 → 1TT) in intramolecular singlet fission (SF). (Triisopropylsilyl)acetylene substituents on the dimer TIPS-BT1 as well as a monomer model TIPS-Tc enable a comparison of photophysical properties, including transient absorption dynamics, as solvent polarity is varied. In nonpolar toluene solutions, TIPS-BT1 decays via radiative and nonradiative pathways to the ground state with no evidence for dynamics related to the initial stages of SF. This contrasts with the behavior of the previously reported unsubstituted dimer BT1 and is likely a consequence of energetic perturbations to the singlet excited-state manifold of TIPS-BT1 by the (trialkylsilyl)acetylene substituents. In polar benzonitrile, two key findings emerge. First, photoexcited TIPS-BT1 shows a bifurcation into both arm-localized (S 1-loc) and dimer-delocalized (S 1-dim) singlet exciton states. The S 1-loc decays to the ground state, and weak temperature dependence of its emissive signatures suggests that once it is formed, it is isolated from S 1-dim. Emissive signatures of the S 1-dim state, on the other hand, are strongly temperature-dependent, and transient absorption dynamics show that S1-dim equilibrates with an intramolecularmore »
- Authors:
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[1]
; [1]
;
[2]
; [2]
; [1]
- Univ. of Colorado, Boulder, CO (United States). Dept. of Chemistry and Biochemistry
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- Publication Date:
- Report Number(s):
- NREL/JA-5900-70332
Journal ID: ISSN 1089-5639; TRN: US1800168
- Grant/Contract Number:
- AC36-08GO28308; AC02-05CH11231; FG02-07ER15890; CHE-1665375
- Type:
- Accepted Manuscript
- Journal Name:
- Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory
- Additional Journal Information:
- Journal Volume: 121; Journal Issue: 48; Journal ID: ISSN 1089-5639
- Publisher:
- American Chemical Society
- Research Org:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- Sponsoring Org:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; SINGLET FISSION; DIMERS; PHOTOPHYSICS
- OSTI Identifier:
- 1410974