Long-Lived Charge Separation in Single Crystals of an Electron Donor Covalently Linked to Four Acceptor Molecules

Jeremy M. Fisher; Malik L. Williams; Jonathan R. Palmer; Natalia E. Powers-Riggs; Ryan M. Young; Michael R. Wasielewski

doi:10.1021/jacs.4c00201

Long-Lived Charge Separation in Single Crystals of an Electron Donor Covalently Linked to Four Acceptor Molecules

Jeremy M. Fisher, Malik L. Williams, Jonathan R. Palmer, Natalia E. Powers-Riggs, Ryan M. Young^*, Michael R. Wasielewski^*

^*Corresponding author for this work

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

8 Scopus citations

Abstract

Crystalline donor-acceptor (D-A) systems serve as an excellent platform for studying CT exciton creation, migration, and dissociation into free charge carriers for solar energy conversion. Donor-acceptor cocrystals have been utilized to develop an understanding of CT exciton formation in ordered organic solids; however, the strong electronic coupling of the D and A units can sometimes limit charge separation lifetimes due to their close proximity. Covalent D-A systems that preorganize specific donor-acceptor structures can assist in engineering crystal morphologies that promote long-lived charge separation to overcome this limitation. Here we investigate photogenerated CT exciton formation in a single crystal of a 2,5,8,11-tetraphenylperylene (PerPh₄) donor to which four identical naphthalene-(1,4:5,8)-bis(dicarboximide) (NDI) electron acceptors are covalently attached at the para positions of the PerPh₄ phenyl groups to yield PerPh₄-NDI₄. X-ray crystallography shows that the four NDIs pack pairwise into two distinct motifs. Two NDI acceptors of one PerPh₄-NDI₄ are positioned over the PerPh₄ donors of adjacent PerPh₄-NDI₄ molecules with the donor and acceptor π-systems having a large dihedral angle between them, while the other two NDIs of PerPh₄-NDI₄ form xylene-NDI van der Waals π-stacks with the corresponding NDIs in adjacent PerPh₄-NDI₄ molecules. Upon selective photoexcitation of PerPh₄ in the single crystal, CT exciton formation occurs in <300 fs yielding electron-hole pairs that live for more than ∼16 μs. This demonstrates the effectiveness of covalently linked D-A systems for engineering single crystal structures that promote efficient and long-lived charge separation for solar energy conversion.

Original language	English (US)
Pages (from-to)	9911-9919
Number of pages	9
Journal	Journal of the American Chemical Society
Volume	146
Issue number	14
DOIs	https://doi.org/10.1021/jacs.4c00201
State	Published - Apr 10 2024

Funding

This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award DE-FG02-99ER14999 (M.R.W.). This work made use of the crystallography facilities at Northwestern University, which have received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF Grant ECCS-2025633), the State of Illinois, the International Institute for Nanotechnology (IIN), and Northwestern University, and Northwestern’s MRSEC program (NSF Grant DMR-1720139). J.R.P. was supported by the NSF Graduate Research Fellowship Program under Grant DGE-2234667. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. This work was adapted from the Ph.D. thesis of J.M.F.

ASJC Scopus subject areas

Catalysis
General Chemistry
Biochemistry
Colloid and Surface Chemistry

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10.1021/jacs.4c00201

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title = "Long-Lived Charge Separation in Single Crystals of an Electron Donor Covalently Linked to Four Acceptor Molecules",

abstract = "Crystalline donor-acceptor (D-A) systems serve as an excellent platform for studying CT exciton creation, migration, and dissociation into free charge carriers for solar energy conversion. Donor-acceptor cocrystals have been utilized to develop an understanding of CT exciton formation in ordered organic solids; however, the strong electronic coupling of the D and A units can sometimes limit charge separation lifetimes due to their close proximity. Covalent D-A systems that preorganize specific donor-acceptor structures can assist in engineering crystal morphologies that promote long-lived charge separation to overcome this limitation. Here we investigate photogenerated CT exciton formation in a single crystal of a 2,5,8,11-tetraphenylperylene (PerPh4) donor to which four identical naphthalene-(1,4:5,8)-bis(dicarboximide) (NDI) electron acceptors are covalently attached at the para positions of the PerPh4 phenyl groups to yield PerPh4-NDI4. X-ray crystallography shows that the four NDIs pack pairwise into two distinct motifs. Two NDI acceptors of one PerPh4-NDI4 are positioned over the PerPh4 donors of adjacent PerPh4-NDI4 molecules with the donor and acceptor π-systems having a large dihedral angle between them, while the other two NDIs of PerPh4-NDI4 form xylene-NDI van der Waals π-stacks with the corresponding NDIs in adjacent PerPh4-NDI4 molecules. Upon selective photoexcitation of PerPh4 in the single crystal, CT exciton formation occurs in <300 fs yielding electron-hole pairs that live for more than ∼16 μs. This demonstrates the effectiveness of covalently linked D-A systems for engineering single crystal structures that promote efficient and long-lived charge separation for solar energy conversion.",

author = "Fisher, {Jeremy M.} and Williams, {Malik L.} and Palmer, {Jonathan R.} and Powers-Riggs, {Natalia E.} and Young, {Ryan M.} and Wasielewski, {Michael R.}",

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AU - Young, Ryan M.

AU - Wasielewski, Michael R.

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AB - Crystalline donor-acceptor (D-A) systems serve as an excellent platform for studying CT exciton creation, migration, and dissociation into free charge carriers for solar energy conversion. Donor-acceptor cocrystals have been utilized to develop an understanding of CT exciton formation in ordered organic solids; however, the strong electronic coupling of the D and A units can sometimes limit charge separation lifetimes due to their close proximity. Covalent D-A systems that preorganize specific donor-acceptor structures can assist in engineering crystal morphologies that promote long-lived charge separation to overcome this limitation. Here we investigate photogenerated CT exciton formation in a single crystal of a 2,5,8,11-tetraphenylperylene (PerPh4) donor to which four identical naphthalene-(1,4:5,8)-bis(dicarboximide) (NDI) electron acceptors are covalently attached at the para positions of the PerPh4 phenyl groups to yield PerPh4-NDI4. X-ray crystallography shows that the four NDIs pack pairwise into two distinct motifs. Two NDI acceptors of one PerPh4-NDI4 are positioned over the PerPh4 donors of adjacent PerPh4-NDI4 molecules with the donor and acceptor π-systems having a large dihedral angle between them, while the other two NDIs of PerPh4-NDI4 form xylene-NDI van der Waals π-stacks with the corresponding NDIs in adjacent PerPh4-NDI4 molecules. Upon selective photoexcitation of PerPh4 in the single crystal, CT exciton formation occurs in <300 fs yielding electron-hole pairs that live for more than ∼16 μs. This demonstrates the effectiveness of covalently linked D-A systems for engineering single crystal structures that promote efficient and long-lived charge separation for solar energy conversion.

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Long-Lived Charge Separation in Single Crystals of an Electron Donor Covalently Linked to Four Acceptor Molecules

Abstract

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CCDC 2311739: Experimental Crystal Structure Determination

CCDC 2279003: Experimental Crystal Structure Determination

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Long-Lived Charge Separation in Single Crystals of an Electron Donor Covalently Linked to Four Acceptor Molecules

Abstract

Funding

ASJC Scopus subject areas

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Datasets

CCDC 2311739: Experimental Crystal Structure Determination

CCDC 2279003: Experimental Crystal Structure Determination

Cite this