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Title: A Direct Mechanism of Ultrafast Intramolecular Singlet Fission in Pentacene Dimers

Abstract

Interest in materials that undergo singlet fission (SF) has been catalyzed by the potential to exceed the Shockley–Queisser limit of solar power conversion efficiency. In conventional materials, the mechanism of SF is an intermolecular process (xSF), which is mediated by charge transfer (CT) states and depends sensitively on crystal packing or molecular collisions. In contrast, recently reported covalently coupled pentacenes yield ~2 triplets per photon absorbed in individual molecules: the hallmark of intramolecular singlet fission (iSF). But, the mechanism of iSF is unclear. Here, using multireference electronic structure calculations and transient absorption spectroscopy, we establish that iSF can occur via a direct coupling mechanism that is independent of CT states. Moreover, we show that a near-degeneracy in electronic state energies induced by vibronic coupling to intramolecular modes of the covalent dimer allows for strong mixing between the correlated triplet pair state and the local excitonic state, despite weak direct coupling.

Authors:
 [1];  [2];  [2];  [2];  [1];  [2];  [2];  [2];  [3];  [2];  [1]
  1. Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
  2. Department of Chemistry, Columbia University, New York, New York 10027, United States
  3. Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1251272
Alternate Identifier(s):
OSTI ID: 1303026
Report Number(s):
BNL-112540-2016-JA
Journal ID: ISSN 2374-7943
Grant/Contract Number:  
SC0014563; SC00112704
Resource Type:
Journal Article: Published Article
Journal Name:
ACS Central Science
Additional Journal Information:
Journal Name: ACS Central Science Journal Volume: 2 Journal Issue: 5; Journal ID: ISSN 2374-7943
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Center for Functional Nanomaterials

Citation Formats

Fuemmeler, Eric G., Sanders, Samuel N., Pun, Andrew B., Kumarasamy, Elango, Zeng, Tao, Miyata, Kiyoshi, Steigerwald, Michael L., Zhu, X. -Y., Sfeir, Matthew Y., Campos, Luis M., and Ananth, Nandini. A Direct Mechanism of Ultrafast Intramolecular Singlet Fission in Pentacene Dimers. United States: N. p., 2016. Web. doi:10.1021/acscentsci.6b00063.
Fuemmeler, Eric G., Sanders, Samuel N., Pun, Andrew B., Kumarasamy, Elango, Zeng, Tao, Miyata, Kiyoshi, Steigerwald, Michael L., Zhu, X. -Y., Sfeir, Matthew Y., Campos, Luis M., & Ananth, Nandini. A Direct Mechanism of Ultrafast Intramolecular Singlet Fission in Pentacene Dimers. United States. https://doi.org/10.1021/acscentsci.6b00063
Fuemmeler, Eric G., Sanders, Samuel N., Pun, Andrew B., Kumarasamy, Elango, Zeng, Tao, Miyata, Kiyoshi, Steigerwald, Michael L., Zhu, X. -Y., Sfeir, Matthew Y., Campos, Luis M., and Ananth, Nandini. 2016. "A Direct Mechanism of Ultrafast Intramolecular Singlet Fission in Pentacene Dimers". United States. https://doi.org/10.1021/acscentsci.6b00063.
@article{osti_1251272,
title = {A Direct Mechanism of Ultrafast Intramolecular Singlet Fission in Pentacene Dimers},
author = {Fuemmeler, Eric G. and Sanders, Samuel N. and Pun, Andrew B. and Kumarasamy, Elango and Zeng, Tao and Miyata, Kiyoshi and Steigerwald, Michael L. and Zhu, X. -Y. and Sfeir, Matthew Y. and Campos, Luis M. and Ananth, Nandini},
abstractNote = {Interest in materials that undergo singlet fission (SF) has been catalyzed by the potential to exceed the Shockley–Queisser limit of solar power conversion efficiency. In conventional materials, the mechanism of SF is an intermolecular process (xSF), which is mediated by charge transfer (CT) states and depends sensitively on crystal packing or molecular collisions. In contrast, recently reported covalently coupled pentacenes yield ~2 triplets per photon absorbed in individual molecules: the hallmark of intramolecular singlet fission (iSF). But, the mechanism of iSF is unclear. Here, using multireference electronic structure calculations and transient absorption spectroscopy, we establish that iSF can occur via a direct coupling mechanism that is independent of CT states. Moreover, we show that a near-degeneracy in electronic state energies induced by vibronic coupling to intramolecular modes of the covalent dimer allows for strong mixing between the correlated triplet pair state and the local excitonic state, despite weak direct coupling.},
doi = {10.1021/acscentsci.6b00063},
url = {https://www.osti.gov/biblio/1251272}, journal = {ACS Central Science},
issn = {2374-7943},
number = 5,
volume = 2,
place = {United States},
year = {2016},
month = {5}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at https://doi.org/10.1021/acscentsci.6b00063

Citation Metrics:
Cited by: 28 works
Citation information provided by
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Works referencing / citing this record:

Conformational Planarization versus Singlet Fission: Distinct Excited-State Dynamics of Cyclooctatetraene-Fused Acene Dimers
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Unified model for singlet fission within a non-conjugated covalent pentacene dimer
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Davydov splitting and singlet fission in excitonically coupled pentacene dimers
journal, January 2019


Conformational Planarization versus Singlet Fission: Distinct Excited-State Dynamics of Cyclooctatetraene-Fused Acene Dimers
journal, March 2018


Unified model for singlet fission within a non-conjugated covalent pentacene dimer
journal, May 2017


Davydov splitting and singlet fission in excitonically coupled pentacene dimers
journal, January 2019


Triplet Harvesting from Intramolecular Singlet Fission in Polytetracene
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Singulettspaltung für Photovoltaikanwendungen mit Injektionseffizienzen von bis zu 130 %
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Conformational Planarization versus Singlet Fission: Distinct Excited-State Dynamics of Cyclooctatetraene-Fused Acene Dimers
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Feinabstimmung von intramolekularem resonantem Förster-Energietransfer und Aktivierung intramolekularer Singulettspaltung
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Singlet Fission for Photovoltaics with 130 % Injection Efficiency
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Tuning Intramolecular Förster Resonance Energy Transfer and Activating Intramolecular Singlet Fission
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Pentacene Dimers as a Critical Tool for the Investigation of Intramolecular Singlet Fission
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Theoretical Studies of Singlet Fission: Searching for Materials and Exploring Mechanisms
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Harnessing singlet exciton fission to break the Shockley–Queisser limit
journal, October 2017


Quintet multiexciton dynamics in singlet fission
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Robust singlet fission in pentacene thin films with tuned charge transfer interactions
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Spin density encodes intramolecular singlet exciton fission in pentacene dimers
journal, January 2019


Tensor network simulation of multi-environmental open quantum dynamics via machine learning and entanglement renormalisation
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Ultra-fast intramolecular singlet fission to persistent multiexcitons by molecular design
journal, August 2019


Singlet exciton fission in a linear tetracene tetramer
journal, January 2018


Coupled double triplet state in singlet fission
journal, January 2018


Singlet fission in self-assembled PDI nanocrystals
journal, January 2018


Influence of the heavy-atom effect on singlet fission: a study of platinum-bridged pentacene dimers
journal, January 2019


Singlet fission in a hexacene dimer: energetics dictate dynamics
journal, January 2020


Structural origins of the electronic properties of materials via time-resolved infrared spectroscopy
journal, January 2019


Singlet fission in spiroconjugated dimers
journal, May 2019


Design of singlet fission chromophores with cyclic (alkyl)(amino) carbene building blocks
journal, June 2019


Quantum dynamical simulation of intramolecular singlet fission in covalently coupled pentacene dimers
journal, July 2019


Heavy-atom effects on intramolecular singlet fission in a conjugated polymer
journal, July 2019


Fluctuating exchange interactions enable quintet multiexciton formation in singlet fission
journal, October 2019


Routes to singlet exciton fission in rubrene crystals and amorphous films
journal, September 2019


Lessons from intramolecular singlet fission with covalently bound chromophores
journal, January 2020