Symmetry-Breaking Charge Separation in Phenylene-Bridged Perylenediimide Dimers

Joaquin M. Alzola; Nikolai A. Tcyrulnikov; Paige J. Brown; Tobin J. Marks; Michael R. Wasielewski; Ryan M. Young

doi:10.1021/acs.jpca.1c05100

Symmetry-Breaking Charge Separation in Phenylene-Bridged Perylenediimide Dimers

Joaquin M. Alzola, Nikolai A. Tcyrulnikov, Paige J. Brown, Tobin J. Marks^*, Michael R. Wasielewski^*, Ryan M. Young^*

^*Corresponding author for this work

Chemistry

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

28 Scopus citations

Abstract

Perylenediimides (PDIs) are important molecular building blocks that are being investigated for their applicability in optoelectronic technologies. Covalently linking multiple PDI acceptors at the 2,5,8,11 (headland) positions adjacent to the PDI carbonyl groups is reported to yield higher power conversion efficiencies in photovoltaic cells relative to PDI acceptors linked at the 1,6,7,12 (bay) positions. While the photophysical properties of PDIs linked via the bay positions have been investigated extensively, those linked at the headland positions have received far less attention. We showed previously that symmetry-breaking charge separation (SB-CS) in PDIs hold promise as a strategy for increasing photovoltaic efficiency. Here we use transient absorption and emission spectroscopies to investigate the competition between SB-CS, fluorescence, and internal conversion in three related PDI dimers linked at the headland positions witho-,m-, andp-phenylene moieties:o-PDI₂,m-PDI₂, andp-PDI₂, respectively. It is found thato-PDI₂supports SB-CS yielding PDI^•+-PDI^•-, which is in equilibrium with theo-PDI₂first excited state in a polar solvent (CH₂Cl₂) whilem-PDI₂andp-PDI₂exhibit accelerated internal conversion due to the motion of the linker along with subnanosecond intersystem crossing (ISC). Electronic coupling and structural dynamics are shown to play a significant role, witho-PDI₂being the only member of the series that exhibits significant through-bond interchromophore coupling. The pronouncedo-PDI₂steric congestion prevents the free internal rotation that leads to rapid deactivation of the excited state in the other dimers.

Original language	English (US)
Pages (from-to)	7633-7643
Number of pages	11
Journal	Journal of Physical Chemistry A
Volume	125
Issue number	35
DOIs	https://doi.org/10.1021/acs.jpca.1c05100
State	Published - Sep 9 2021

Funding

This work was supported as part of the Center for Light Energy Activated Redox Processes (LEAP), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Award # DE-SC0001059 (J.M.A., M.R.W., R.M.Y., synthesis and spectroscopy). N.A.T. was supported by The R. Marshall and Antonia G. Wilson Chemistry Fund. P.J.B. was supported by an NSF Graduate Research Fellowship under Award DGE-1842165. NMR and MS measurements in this work were performed at the IMSERC at Northwestern University, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF NNCI-1542205), the State of Illinois, and International Institute for Nanotechnology (IIN). We thank Dr. S. Shafaie for collecting high-resolution mass spectrometric data.

ASJC Scopus subject areas

Physical and Theoretical Chemistry

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title = "Symmetry-Breaking Charge Separation in Phenylene-Bridged Perylenediimide Dimers",

abstract = "Perylenediimides (PDIs) are important molecular building blocks that are being investigated for their applicability in optoelectronic technologies. Covalently linking multiple PDI acceptors at the 2,5,8,11 (headland) positions adjacent to the PDI carbonyl groups is reported to yield higher power conversion efficiencies in photovoltaic cells relative to PDI acceptors linked at the 1,6,7,12 (bay) positions. While the photophysical properties of PDIs linked via the bay positions have been investigated extensively, those linked at the headland positions have received far less attention. We showed previously that symmetry-breaking charge separation (SB-CS) in PDIs hold promise as a strategy for increasing photovoltaic efficiency. Here we use transient absorption and emission spectroscopies to investigate the competition between SB-CS, fluorescence, and internal conversion in three related PDI dimers linked at the headland positions witho-,m-, andp-phenylene moieties:o-PDI2,m-PDI2, andp-PDI2, respectively. It is found thato-PDI2supports SB-CS yielding PDI•+-PDI•-, which is in equilibrium with theo-PDI2first excited state in a polar solvent (CH2Cl2) whilem-PDI2andp-PDI2exhibit accelerated internal conversion due to the motion of the linker along with subnanosecond intersystem crossing (ISC). Electronic coupling and structural dynamics are shown to play a significant role, witho-PDI2being the only member of the series that exhibits significant through-bond interchromophore coupling. The pronouncedo-PDI2steric congestion prevents the free internal rotation that leads to rapid deactivation of the excited state in the other dimers.",

author = "Alzola, {Joaquin M.} and Tcyrulnikov, {Nikolai A.} and Brown, {Paige J.} and Marks, {Tobin J.} and Wasielewski, {Michael R.} and Young, {Ryan M.}",

note = "Publisher Copyright: {\textcopyright} 2021 American Chemical Society",

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AU - Alzola, Joaquin M.

AU - Tcyrulnikov, Nikolai A.

AU - Brown, Paige J.

AU - Marks, Tobin J.

AU - Wasielewski, Michael R.

AU - Young, Ryan M.

PY - 2021/9/9

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N2 - Perylenediimides (PDIs) are important molecular building blocks that are being investigated for their applicability in optoelectronic technologies. Covalently linking multiple PDI acceptors at the 2,5,8,11 (headland) positions adjacent to the PDI carbonyl groups is reported to yield higher power conversion efficiencies in photovoltaic cells relative to PDI acceptors linked at the 1,6,7,12 (bay) positions. While the photophysical properties of PDIs linked via the bay positions have been investigated extensively, those linked at the headland positions have received far less attention. We showed previously that symmetry-breaking charge separation (SB-CS) in PDIs hold promise as a strategy for increasing photovoltaic efficiency. Here we use transient absorption and emission spectroscopies to investigate the competition between SB-CS, fluorescence, and internal conversion in three related PDI dimers linked at the headland positions witho-,m-, andp-phenylene moieties:o-PDI2,m-PDI2, andp-PDI2, respectively. It is found thato-PDI2supports SB-CS yielding PDI•+-PDI•-, which is in equilibrium with theo-PDI2first excited state in a polar solvent (CH2Cl2) whilem-PDI2andp-PDI2exhibit accelerated internal conversion due to the motion of the linker along with subnanosecond intersystem crossing (ISC). Electronic coupling and structural dynamics are shown to play a significant role, witho-PDI2being the only member of the series that exhibits significant through-bond interchromophore coupling. The pronouncedo-PDI2steric congestion prevents the free internal rotation that leads to rapid deactivation of the excited state in the other dimers.

AB - Perylenediimides (PDIs) are important molecular building blocks that are being investigated for their applicability in optoelectronic technologies. Covalently linking multiple PDI acceptors at the 2,5,8,11 (headland) positions adjacent to the PDI carbonyl groups is reported to yield higher power conversion efficiencies in photovoltaic cells relative to PDI acceptors linked at the 1,6,7,12 (bay) positions. While the photophysical properties of PDIs linked via the bay positions have been investigated extensively, those linked at the headland positions have received far less attention. We showed previously that symmetry-breaking charge separation (SB-CS) in PDIs hold promise as a strategy for increasing photovoltaic efficiency. Here we use transient absorption and emission spectroscopies to investigate the competition between SB-CS, fluorescence, and internal conversion in three related PDI dimers linked at the headland positions witho-,m-, andp-phenylene moieties:o-PDI2,m-PDI2, andp-PDI2, respectively. It is found thato-PDI2supports SB-CS yielding PDI•+-PDI•-, which is in equilibrium with theo-PDI2first excited state in a polar solvent (CH2Cl2) whilem-PDI2andp-PDI2exhibit accelerated internal conversion due to the motion of the linker along with subnanosecond intersystem crossing (ISC). Electronic coupling and structural dynamics are shown to play a significant role, witho-PDI2being the only member of the series that exhibits significant through-bond interchromophore coupling. The pronouncedo-PDI2steric congestion prevents the free internal rotation that leads to rapid deactivation of the excited state in the other dimers.

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ER -

Symmetry-Breaking Charge Separation in Phenylene-Bridged Perylenediimide Dimers

Abstract

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