Singlet Fission in Concentrated TIPS-Pentacene Solutions: The Role of Excimers and Aggregates

Miroslav Dvořák; Shyamal K.K. Prasad; Cameron B. Dover; Chelsea R. Forest; Akasha Kaleem; Rowan W. Macqueen; Anthony J. Petty; Roslyn Forecast; Jonathon E. Beves; John E. Anthony; Murad J.Y. Tayebjee; Asaph Widmer-Cooper; Pall Thordarson; Timothy W. Schmidt

doi:10.1021/jacs.1c05767

Singlet Fission in Concentrated TIPS-Pentacene Solutions: The Role of Excimers and Aggregates

Miroslav Dvořák, Shyamal K.K. Prasad, Cameron B. Dover, Chelsea R. Forest, Akasha Kaleem, Rowan W. Macqueen, Anthony J. Petty, Roslyn Forecast, Jonathon E. Beves, John E. Anthony, Murad J.Y. Tayebjee, Asaph Widmer-Cooper, Pall Thordarson, Timothy W. Schmidt

Research output: Contribution to journal › Article › peer-review

17 Scopus citations

Abstract

The excited-state dynamics of 6,13-bis(triisopropylsilylethynyl)pentacene is investigated to determine the role of excimer and aggregate formation in singlet fission in high-concentration solutions. Photoluminescence spectra were measured by excitation with the evanescent wave in total internal reflection, in order to avoid reabsorption effects. The spectra over nearly two magnitudes of concentration were nearly identical, with no evidence for excimer emission. Time-correlated single-photon counting measurements confirm that the fluorescence lifetime shortens with concentration. The observed rate constant grows at high concentrations, and this effect is modeled in terms of the hard-sphere radial distribution function. NMR measurements confirm that aggregation takes place with a binding constant of between 0.14 and 0.43 M-1. Transient absorption measurements are consistent with a diffusive encounter mechanism for singlet fission, with hints of more rapid singlet fission in aggregates at the highest concentration measured. These data show that excimers do not play the role of an emissive intermediate in exothermic singlet fission in solution and that, while aggregation occurs at higher concentrations, the mechanism of singlet fission remains dominated by diffusive encounters.

Original language	English
Pages (from-to)	13749-13758
Number of pages	10
Journal	Journal of the American Chemical Society
Volume	143
Issue number	34
DOIs	https://doi.org/10.1021/jacs.1c05767
State	Published - Sep 1 2021

Bibliographical note

Funding Information:
This work was supported by the Australian Research Council (Centre of Excellence in Exciton Science CE170100026). This program has been supported by the Australian Government through the Australian Renewable Energy Agency (ARENA). M.D. acknowledges CAAS grant no. CZ.02.1.01/0.0/0.0/16_019/0000778.

Publisher Copyright:
© 2021 American Chemical Society.

ASJC Scopus subject areas

Catalysis
Chemistry (all)
Biochemistry
Colloid and Surface Chemistry

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Dvořák, M., Prasad, S. K. K., Dover, C. B., Forest, C. R., Kaleem, A., Macqueen, R. W., Petty, A. J., Forecast, R., Beves, J. E., Anthony, J. E., Tayebjee, M. J. Y., Widmer-Cooper, A., Thordarson, P., & Schmidt, T. W. (2021). Singlet Fission in Concentrated TIPS-Pentacene Solutions: The Role of Excimers and Aggregates. Journal of the American Chemical Society, 143(34), 13749-13758. https://doi.org/10.1021/jacs.1c05767

@article{63dfe11259a747df841d79819f9db570,

title = "Singlet Fission in Concentrated TIPS-Pentacene Solutions: The Role of Excimers and Aggregates",

abstract = "The excited-state dynamics of 6,13-bis(triisopropylsilylethynyl)pentacene is investigated to determine the role of excimer and aggregate formation in singlet fission in high-concentration solutions. Photoluminescence spectra were measured by excitation with the evanescent wave in total internal reflection, in order to avoid reabsorption effects. The spectra over nearly two magnitudes of concentration were nearly identical, with no evidence for excimer emission. Time-correlated single-photon counting measurements confirm that the fluorescence lifetime shortens with concentration. The observed rate constant grows at high concentrations, and this effect is modeled in terms of the hard-sphere radial distribution function. NMR measurements confirm that aggregation takes place with a binding constant of between 0.14 and 0.43 M-1. Transient absorption measurements are consistent with a diffusive encounter mechanism for singlet fission, with hints of more rapid singlet fission in aggregates at the highest concentration measured. These data show that excimers do not play the role of an emissive intermediate in exothermic singlet fission in solution and that, while aggregation occurs at higher concentrations, the mechanism of singlet fission remains dominated by diffusive encounters.",

author = "Miroslav Dvo{\v r}{\'a}k and Prasad, {Shyamal K.K.} and Dover, {Cameron B.} and Forest, {Chelsea R.} and Akasha Kaleem and Macqueen, {Rowan W.} and Petty, {Anthony J.} and Roslyn Forecast and Beves, {Jonathon E.} and Anthony, {John E.} and Tayebjee, {Murad J.Y.} and Asaph Widmer-Cooper and Pall Thordarson and Schmidt, {Timothy W.}",

note = "Funding Information: This work was supported by the Australian Research Council (Centre of Excellence in Exciton Science CE170100026). This program has been supported by the Australian Government through the Australian Renewable Energy Agency (ARENA). M.D. acknowledges CAAS grant no. CZ.02.1.01/0.0/0.0/16_019/0000778. Publisher Copyright: {\textcopyright} 2021 American Chemical Society.",

year = "2021",

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doi = "10.1021/jacs.1c05767",

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Dvořák, M, Prasad, SKK, Dover, CB, Forest, CR, Kaleem, A, Macqueen, RW, Petty, AJ, Forecast, R, Beves, JE, Anthony, JE, Tayebjee, MJY, Widmer-Cooper, A, Thordarson, P & Schmidt, TW 2021, 'Singlet Fission in Concentrated TIPS-Pentacene Solutions: The Role of Excimers and Aggregates', Journal of the American Chemical Society, vol. 143, no. 34, pp. 13749-13758. https://doi.org/10.1021/jacs.1c05767

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T1 - Singlet Fission in Concentrated TIPS-Pentacene Solutions

T2 - The Role of Excimers and Aggregates

AU - Dvořák, Miroslav

AU - Prasad, Shyamal K.K.

AU - Dover, Cameron B.

AU - Forest, Chelsea R.

AU - Kaleem, Akasha

AU - Macqueen, Rowan W.

AU - Petty, Anthony J.

AU - Forecast, Roslyn

AU - Beves, Jonathon E.

AU - Anthony, John E.

AU - Tayebjee, Murad J.Y.

AU - Widmer-Cooper, Asaph

AU - Thordarson, Pall

AU - Schmidt, Timothy W.

N1 - Funding Information: This work was supported by the Australian Research Council (Centre of Excellence in Exciton Science CE170100026). This program has been supported by the Australian Government through the Australian Renewable Energy Agency (ARENA). M.D. acknowledges CAAS grant no. CZ.02.1.01/0.0/0.0/16_019/0000778. Publisher Copyright: © 2021 American Chemical Society.

PY - 2021/9/1

Y1 - 2021/9/1

N2 - The excited-state dynamics of 6,13-bis(triisopropylsilylethynyl)pentacene is investigated to determine the role of excimer and aggregate formation in singlet fission in high-concentration solutions. Photoluminescence spectra were measured by excitation with the evanescent wave in total internal reflection, in order to avoid reabsorption effects. The spectra over nearly two magnitudes of concentration were nearly identical, with no evidence for excimer emission. Time-correlated single-photon counting measurements confirm that the fluorescence lifetime shortens with concentration. The observed rate constant grows at high concentrations, and this effect is modeled in terms of the hard-sphere radial distribution function. NMR measurements confirm that aggregation takes place with a binding constant of between 0.14 and 0.43 M-1. Transient absorption measurements are consistent with a diffusive encounter mechanism for singlet fission, with hints of more rapid singlet fission in aggregates at the highest concentration measured. These data show that excimers do not play the role of an emissive intermediate in exothermic singlet fission in solution and that, while aggregation occurs at higher concentrations, the mechanism of singlet fission remains dominated by diffusive encounters.

AB - The excited-state dynamics of 6,13-bis(triisopropylsilylethynyl)pentacene is investigated to determine the role of excimer and aggregate formation in singlet fission in high-concentration solutions. Photoluminescence spectra were measured by excitation with the evanescent wave in total internal reflection, in order to avoid reabsorption effects. The spectra over nearly two magnitudes of concentration were nearly identical, with no evidence for excimer emission. Time-correlated single-photon counting measurements confirm that the fluorescence lifetime shortens with concentration. The observed rate constant grows at high concentrations, and this effect is modeled in terms of the hard-sphere radial distribution function. NMR measurements confirm that aggregation takes place with a binding constant of between 0.14 and 0.43 M-1. Transient absorption measurements are consistent with a diffusive encounter mechanism for singlet fission, with hints of more rapid singlet fission in aggregates at the highest concentration measured. These data show that excimers do not play the role of an emissive intermediate in exothermic singlet fission in solution and that, while aggregation occurs at higher concentrations, the mechanism of singlet fission remains dominated by diffusive encounters.

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DO - 10.1021/jacs.1c05767

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C2 - 34397219

AN - SCOPUS:85114194260

SN - 0002-7863

VL - 143

SP - 13749

EP - 13758

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

IS - 34

ER -

Singlet Fission in Concentrated TIPS-Pentacene Solutions: The Role of Excimers and Aggregates

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