Non-fullerene acceptors with direct and indirect hexa-fluorination afford >17% efficiency in polymer solar cells

Guoping Li; Liang Wen Feng; Subhrangsu Mukherjee; Leighton O. Jones; Robert M. Jacobberger; Wei Huang; Ryan M. Young; Robert M. Pankow; Weigang Zhu; Norman Lu; Kevin L. Kohlstedt; Vinod K. Sangwan; Michael R. Wasielewski; Mark C. Hersam; George C. Schatz; Dean M. Delongchamp; Antonio Facchetti; Tobin J. Marks

doi:10.1039/d1ee03225a

Non-fullerene acceptors with direct and indirect hexa-fluorination afford >17% efficiency in polymer solar cells

Guoping Li, Liang Wen Feng, Subhrangsu Mukherjee, Leighton O. Jones, Robert M. Jacobberger, Wei Huang, Ryan M. Young^*, Robert M. Pankow, Weigang Zhu, Norman Lu, Kevin L. Kohlstedt^*, Vinod K. Sangwan^*, Michael R. Wasielewski^*, Mark C. Hersam^*, George C. Schatz^*, Dean M. Delongchamp^*, Antonio Facchetti^*, Tobin J. Marks^*

^*Corresponding author for this work

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

81 Scopus citations

Abstract

The rational molecular design of non-fullerene acceptors (NFAs) in organic solar cells (OSCs) can profoundly influence the photovoltaic (OPV) performance. To date, NFA fluorination has proven beneficial to cell performance. However, there is a lack of comprehensive understanding of how various fluorination modalities influence film morphology, carrier mobility, molecular packing, other structural properties, electronic structure, exciton separation, and charge transport, that determine ultimate cell efficiency. Here, we compare two types of end group (EG) fluorination patterns on Y6-based A-DAD-A cores, resulting in highly efficient NFAs: direct skeletal fluorination (BTF) and indirect trifluoromethyl fluorination (BTFM). These two patterns induce distinctive behaviors in the active layer blends with a chlorinated donor polymer D18-Cl and the additive, 1-chloronaphthalene, affording high PCE values of 17.30% (BTF + additive) and 17.10% (BTFM, no-additive). The BTFvs.BTFM OSC performance trends can be correlated with diffraction-derived differences in molecular packing. Density functional theory (DFT) reveals remarkably low internal reorganization energies and high electronic coupling between NFA dimers, greater and more numerous than in other NFAs reported to date, thus providing extended 3D charge transport networks in the thin film crystalline domains. Transient absorption spectroscopy reveals that hole transfer from the acceptor to the donor occurs in <300 fs and that photoexcited carriers persist for hundreds of ns in each blend film. The contrasting role of the additive in BTF and BTFM cells is further clarified by recombination dynamics analysis using in situ photocurrent and impedance spectroscopy. Overall, this work provides guidance for developing new NFAs via direct and indirect fluorination strategies for high efficiency OSCs.

Original language	English (US)
Pages (from-to)	645-659
Number of pages	15
Journal	Energy and Environmental Science
Volume	15
Issue number	2
DOIs	https://doi.org/10.1039/d1ee03225a
State	Published - Feb 2022

Funding

This work was supported by U.S. Office of Naval Research Contract #N00014-20-1-2116 (G. L.: material synthesis and characterizations; L. W. F.: photovoltaic device fabrication and measurement), by the U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design Award #-70NANB10 H005 (S. M.:GIWAXS and RSoXS analysis), and by the North-western University Materials Research Science and Engineering Center Award NSF DMR-1720139 (V. K. S.: impedance measurements). Theory development (K. L. K., L. O. J., G. C. S.) was supported by DOE grant DE-AC02-06CH11357. Transient optical spectroscopy was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award DE-FG02-99ER14999 (MRW). This work made use of the EPIC, BioCryo, Keck-II, and/or SPID facilities of Northwestern’s NUANCE Center, which received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSFECCS-1542205) and Northwestern University Materials Research Science and Engineering Center (NSF DMR-1720139). We thank the Integrated Molecular Structure Education and Research Center (IMSERC) for characterization facilities supported by Northwestern U.S. National Science Foundation (NSF) under NSF CHE1048773, Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF NNCI-1542205), the State of Illinois, and International Institute for Nanotechnology (IIN). This work was supported by the Department of Energy under contract no. DE-AC02-05CH11231 and used resources at beamline 8-ID-E of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. This research used beamlines 7-ID-1 (SST-1) and 11-BM (CMS) of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704.This work (IPDA) made use of the MatCI Facility which receives support from the MRSEC Program (NSF DMR-1720139) of the Materials Research Center at Northwestern University. W. Zhu thanks the Open Foundation of State Key Laboratory of Electronic Thin Films and Integrated Devices (KFJJ202001, Unconventional Organic Nonlinear Optical Hybrid Materials and Devices) for partial financial support. Dr Jianhua Chen, and Mr Brendan Kerwin are acknowledged for their support on some characterization techniques. The theory research was also supported in part through the computational resources and staff contributions provided for the Quest high performance computing facility at North-western University which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern University Information Technology. This work made use of the GIANTFab core facility at Northwestern University. GIANTFab is supported by the Institute for Sustainability and Energy at Northwestern and the Office of the Vice President for Research at Northwestern. Dr Ding Zheng at Department of Chemistry, Northwestern University was acknowledged for his support in some characterization studies. Note that certain commercial equipment, instruments, or materials are identified in this paper to specify the experimental procedure adequately. Such identification is neither intended to imply recommendation or endorsement by NIST, nor is it intended to imply that the materials or equipment identified are necessarily the best available for the purpose.

ASJC Scopus subject areas

Environmental Chemistry
Renewable Energy, Sustainability and the Environment
Nuclear Energy and Engineering
Pollution

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1039/d1ee03225a

Cite this

Li, G., Feng, L. W., Mukherjee, S., Jones, L. O., Jacobberger, R. M., Huang, W., Young, R. M., Pankow, R. M., Zhu, W., Lu, N., Kohlstedt, K. L., Sangwan, V. K., Wasielewski, M. R., Hersam, M. C., Schatz, G. C., Delongchamp, D. M., Facchetti, A., & Marks, T. J. (2022). Non-fullerene acceptors with direct and indirect hexa-fluorination afford >17% efficiency in polymer solar cells. Energy and Environmental Science, 15(2), 645-659. https://doi.org/10.1039/d1ee03225a

@article{714dbc3cdac347b1a37d49c79bad5c5c,

title = "Non-fullerene acceptors with direct and indirect hexa-fluorination afford >17% efficiency in polymer solar cells",

abstract = "The rational molecular design of non-fullerene acceptors (NFAs) in organic solar cells (OSCs) can profoundly influence the photovoltaic (OPV) performance. To date, NFA fluorination has proven beneficial to cell performance. However, there is a lack of comprehensive understanding of how various fluorination modalities influence film morphology, carrier mobility, molecular packing, other structural properties, electronic structure, exciton separation, and charge transport, that determine ultimate cell efficiency. Here, we compare two types of end group (EG) fluorination patterns on Y6-based A-DAD-A cores, resulting in highly efficient NFAs: direct skeletal fluorination (BTF) and indirect trifluoromethyl fluorination (BTFM). These two patterns induce distinctive behaviors in the active layer blends with a chlorinated donor polymer D18-Cl and the additive, 1-chloronaphthalene, affording high PCE values of 17.30% (BTF + additive) and 17.10% (BTFM, no-additive). The BTFvs.BTFM OSC performance trends can be correlated with diffraction-derived differences in molecular packing. Density functional theory (DFT) reveals remarkably low internal reorganization energies and high electronic coupling between NFA dimers, greater and more numerous than in other NFAs reported to date, thus providing extended 3D charge transport networks in the thin film crystalline domains. Transient absorption spectroscopy reveals that hole transfer from the acceptor to the donor occurs in <300 fs and that photoexcited carriers persist for hundreds of ns in each blend film. The contrasting role of the additive in BTF and BTFM cells is further clarified by recombination dynamics analysis using in situ photocurrent and impedance spectroscopy. Overall, this work provides guidance for developing new NFAs via direct and indirect fluorination strategies for high efficiency OSCs.",

author = "Guoping Li and Feng, {Liang Wen} and Subhrangsu Mukherjee and Jones, {Leighton O.} and Jacobberger, {Robert M.} and Wei Huang and Young, {Ryan M.} and Pankow, {Robert M.} and Weigang Zhu and Norman Lu and Kohlstedt, {Kevin L.} and Sangwan, {Vinod K.} and Wasielewski, {Michael R.} and Hersam, {Mark C.} and Schatz, {George C.} and Delongchamp, {Dean M.} and Antonio Facchetti and Marks, {Tobin J.}",

note = "Funding Information: This work was supported by U.S. Office of Naval Research Contract #N00014-20-1-2116 (G. L.: material synthesis and characterizations; L. W. F.: photovoltaic device fabrication and measurement), by the U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design Award #-70NANB10 H005 (S. M.:GIWAXS and RSoXS analysis), and by the North-western University Materials Research Science and Engineering Center Award NSF DMR-1720139 (V. K. S.: impedance measurements). Theory development (K. L. K., L. O. J., G. C. S.) was supported by DOE grant DE-AC02-06CH11357. Transient optical spectroscopy was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award DE-FG02-99ER14999 (MRW). This work made use of the EPIC, BioCryo, Keck-II, and/or SPID facilities of Northwestern{\textquoteright}s NUANCE Center, which received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSFECCS-1542205) and Northwestern University Materials Research Science and Engineering Center (NSF DMR-1720139). We thank the Integrated Molecular Structure Education and Research Center (IMSERC) for characterization facilities supported by Northwestern U.S. National Science Foundation (NSF) under NSF CHE1048773, Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF NNCI-1542205), the State of Illinois, and International Institute for Nanotechnology (IIN). This work was supported by the Department of Energy under contract no. DE-AC02-05CH11231 and used resources at beamline 8-ID-E of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. This research used beamlines 7-ID-1 (SST-1) and 11-BM (CMS) of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704.This work (IPDA) made use of the MatCI Facility which receives support from the MRSEC Program (NSF DMR-1720139) of the Materials Research Center at Northwestern University. W. Zhu thanks the Open Foundation of State Key Laboratory of Electronic Thin Films and Integrated Devices (KFJJ202001, Unconventional Organic Nonlinear Optical Hybrid Materials and Devices) for partial financial support. Dr Jianhua Chen, and Mr Brendan Kerwin are acknowledged for their support on some characterization techniques. The theory research was also supported in part through the computational resources and staff contributions provided for the Quest high performance computing facility at North-western University which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern University Information Technology. This work made use of the GIANTFab core facility at Northwestern University. GIANTFab is supported by the Institute for Sustainability and Energy at Northwestern and the Office of the Vice President for Research at Northwestern. Dr Ding Zheng at Department of Chemistry, Northwestern University was acknowledged for his support in some characterization studies. Note that certain commercial equipment, instruments, or materials are identified in this paper to specify the experimental procedure adequately. Such identification is neither intended to imply recommendation or endorsement by NIST, nor is it intended to imply that the materials or equipment identified are necessarily the best available for the purpose. Publisher Copyright: {\textcopyright} 2022 The Royal Society of Chemistry.",

year = "2022",

month = feb,

doi = "10.1039/d1ee03225a",

language = "English (US)",

volume = "15",

pages = "645--659",

journal = "Energy and Environmental Science",

issn = "1754-5692",

publisher = "Royal Society of Chemistry",

number = "2",

}

Li, G, Feng, LW, Mukherjee, S, Jones, LO, Jacobberger, RM, Huang, W, Young, RM, Pankow, RM, Zhu, W, Lu, N, Kohlstedt, KL , Sangwan, VK , Wasielewski, MR , Hersam, MC , Schatz, GC, Delongchamp, DM, Facchetti, A & Marks, TJ 2022, 'Non-fullerene acceptors with direct and indirect hexa-fluorination afford >17% efficiency in polymer solar cells', Energy and Environmental Science, vol. 15, no. 2, pp. 645-659. https://doi.org/10.1039/d1ee03225a

TY - JOUR

T1 - Non-fullerene acceptors with direct and indirect hexa-fluorination afford >17% efficiency in polymer solar cells

AU - Li, Guoping

AU - Feng, Liang Wen

AU - Mukherjee, Subhrangsu

AU - Jones, Leighton O.

AU - Jacobberger, Robert M.

AU - Huang, Wei

AU - Young, Ryan M.

AU - Pankow, Robert M.

AU - Zhu, Weigang

AU - Lu, Norman

AU - Kohlstedt, Kevin L.

AU - Sangwan, Vinod K.

AU - Wasielewski, Michael R.

AU - Hersam, Mark C.

AU - Schatz, George C.

AU - Delongchamp, Dean M.

AU - Facchetti, Antonio

AU - Marks, Tobin J.

N1 - Funding Information: This work was supported by U.S. Office of Naval Research Contract #N00014-20-1-2116 (G. L.: material synthesis and characterizations; L. W. F.: photovoltaic device fabrication and measurement), by the U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design Award #-70NANB10 H005 (S. M.:GIWAXS and RSoXS analysis), and by the North-western University Materials Research Science and Engineering Center Award NSF DMR-1720139 (V. K. S.: impedance measurements). Theory development (K. L. K., L. O. J., G. C. S.) was supported by DOE grant DE-AC02-06CH11357. Transient optical spectroscopy was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award DE-FG02-99ER14999 (MRW). This work made use of the EPIC, BioCryo, Keck-II, and/or SPID facilities of Northwestern’s NUANCE Center, which received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSFECCS-1542205) and Northwestern University Materials Research Science and Engineering Center (NSF DMR-1720139). We thank the Integrated Molecular Structure Education and Research Center (IMSERC) for characterization facilities supported by Northwestern U.S. National Science Foundation (NSF) under NSF CHE1048773, Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF NNCI-1542205), the State of Illinois, and International Institute for Nanotechnology (IIN). This work was supported by the Department of Energy under contract no. DE-AC02-05CH11231 and used resources at beamline 8-ID-E of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. This research used beamlines 7-ID-1 (SST-1) and 11-BM (CMS) of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704.This work (IPDA) made use of the MatCI Facility which receives support from the MRSEC Program (NSF DMR-1720139) of the Materials Research Center at Northwestern University. W. Zhu thanks the Open Foundation of State Key Laboratory of Electronic Thin Films and Integrated Devices (KFJJ202001, Unconventional Organic Nonlinear Optical Hybrid Materials and Devices) for partial financial support. Dr Jianhua Chen, and Mr Brendan Kerwin are acknowledged for their support on some characterization techniques. The theory research was also supported in part through the computational resources and staff contributions provided for the Quest high performance computing facility at North-western University which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern University Information Technology. This work made use of the GIANTFab core facility at Northwestern University. GIANTFab is supported by the Institute for Sustainability and Energy at Northwestern and the Office of the Vice President for Research at Northwestern. Dr Ding Zheng at Department of Chemistry, Northwestern University was acknowledged for his support in some characterization studies. Note that certain commercial equipment, instruments, or materials are identified in this paper to specify the experimental procedure adequately. Such identification is neither intended to imply recommendation or endorsement by NIST, nor is it intended to imply that the materials or equipment identified are necessarily the best available for the purpose. Publisher Copyright: © 2022 The Royal Society of Chemistry.

PY - 2022/2

Y1 - 2022/2

N2 - The rational molecular design of non-fullerene acceptors (NFAs) in organic solar cells (OSCs) can profoundly influence the photovoltaic (OPV) performance. To date, NFA fluorination has proven beneficial to cell performance. However, there is a lack of comprehensive understanding of how various fluorination modalities influence film morphology, carrier mobility, molecular packing, other structural properties, electronic structure, exciton separation, and charge transport, that determine ultimate cell efficiency. Here, we compare two types of end group (EG) fluorination patterns on Y6-based A-DAD-A cores, resulting in highly efficient NFAs: direct skeletal fluorination (BTF) and indirect trifluoromethyl fluorination (BTFM). These two patterns induce distinctive behaviors in the active layer blends with a chlorinated donor polymer D18-Cl and the additive, 1-chloronaphthalene, affording high PCE values of 17.30% (BTF + additive) and 17.10% (BTFM, no-additive). The BTFvs.BTFM OSC performance trends can be correlated with diffraction-derived differences in molecular packing. Density functional theory (DFT) reveals remarkably low internal reorganization energies and high electronic coupling between NFA dimers, greater and more numerous than in other NFAs reported to date, thus providing extended 3D charge transport networks in the thin film crystalline domains. Transient absorption spectroscopy reveals that hole transfer from the acceptor to the donor occurs in <300 fs and that photoexcited carriers persist for hundreds of ns in each blend film. The contrasting role of the additive in BTF and BTFM cells is further clarified by recombination dynamics analysis using in situ photocurrent and impedance spectroscopy. Overall, this work provides guidance for developing new NFAs via direct and indirect fluorination strategies for high efficiency OSCs.

AB - The rational molecular design of non-fullerene acceptors (NFAs) in organic solar cells (OSCs) can profoundly influence the photovoltaic (OPV) performance. To date, NFA fluorination has proven beneficial to cell performance. However, there is a lack of comprehensive understanding of how various fluorination modalities influence film morphology, carrier mobility, molecular packing, other structural properties, electronic structure, exciton separation, and charge transport, that determine ultimate cell efficiency. Here, we compare two types of end group (EG) fluorination patterns on Y6-based A-DAD-A cores, resulting in highly efficient NFAs: direct skeletal fluorination (BTF) and indirect trifluoromethyl fluorination (BTFM). These two patterns induce distinctive behaviors in the active layer blends with a chlorinated donor polymer D18-Cl and the additive, 1-chloronaphthalene, affording high PCE values of 17.30% (BTF + additive) and 17.10% (BTFM, no-additive). The BTFvs.BTFM OSC performance trends can be correlated with diffraction-derived differences in molecular packing. Density functional theory (DFT) reveals remarkably low internal reorganization energies and high electronic coupling between NFA dimers, greater and more numerous than in other NFAs reported to date, thus providing extended 3D charge transport networks in the thin film crystalline domains. Transient absorption spectroscopy reveals that hole transfer from the acceptor to the donor occurs in <300 fs and that photoexcited carriers persist for hundreds of ns in each blend film. The contrasting role of the additive in BTF and BTFM cells is further clarified by recombination dynamics analysis using in situ photocurrent and impedance spectroscopy. Overall, this work provides guidance for developing new NFAs via direct and indirect fluorination strategies for high efficiency OSCs.

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DO - 10.1039/d1ee03225a

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JO - Energy and Environmental Science

JF - Energy and Environmental Science

IS - 2

ER -

Non-fullerene acceptors with direct and indirect hexa-fluorination afford >17% efficiency in polymer solar cells

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CCDC 2109328: Experimental Crystal Structure Determination

CCDC 2109327: Experimental Crystal Structure Determination

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Non-fullerene acceptors with direct and indirect hexa-fluorination afford >17% efficiency in polymer solar cells

Abstract

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ASJC Scopus subject areas

UN SDGs

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Datasets

CCDC 2109328: Experimental Crystal Structure Determination

CCDC 2109327: Experimental Crystal Structure Determination

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