Systematically Controlling Acceptor Fluorination Optimizes Hierarchical Morphology, Vertical Phase Separation, and Efficiency in Non-Fullerene Organic Solar Cells

Xiaohua Zhang; Guoping Li; Subhrangsu Mukherjee; Wei Huang; Ding Zheng; Liang Wen Feng; Yao Chen; Jianglin Wu; Vinod K. Sangwan; Mark C. Hersam; Dean M. DeLongchamp; Junsheng Yu; Antonio Facchetti; Tobin J. Marks

doi:10.1002/aenm.202102172

Systematically Controlling Acceptor Fluorination Optimizes Hierarchical Morphology, Vertical Phase Separation, and Efficiency in Non-Fullerene Organic Solar Cells

Xiaohua Zhang, Guoping Li, Subhrangsu Mukherjee, Wei Huang, Ding Zheng, Liang Wen Feng, Yao Chen, Jianglin Wu, Vinod K. Sangwan^*, Mark C. Hersam^*, Dean M. DeLongchamp^*, Junsheng Yu^*, Antonio Facchetti^*, Tobin J. Marks^*

^*Corresponding author for this work

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

51 Scopus citations

Abstract

Non-fullerene acceptor (NFA) end group (EG) functionalization, especially by fluorination, affects not only the energetics but also the morphology of bulk-heterojunction (BHJ) organic solar cell (OSC) active layers, thereby influencing the power conversion efficiency (PCE) and other metrics of NFA-based OSCs. However, a quantitative understanding of how varying the degrees of NFA fluorination influence the blend morphological and photovoltaic properties remains elusive. Here a series of three A-DAD-A type NFAs (D = π-donor group and A = π-acceptor EG) which systematically increase the degree of EG fluorination and comprehensively investigate the resulting blends with the polymer donor PM6 in terms of optical properties, electronic structure, film crystallinity, charge carrier transport, and OSC performance is reported. The results indicate that the most highly fluorinated NFA, BT-BO-L4F, achieves an optimal BHJ hierarchical morphology where enhanced NFA molecule intermolecular π–π stacking and optimal vertical phase gradation are achieved in the BHJ blend. These factors also promote optimum NFA-cathode contact, more balanced electron and hole mobility, and suppress both monomolecular and bimolecular recombination. As a result, both the short-circuit current density and fill factor in this OSC series progressively increase with increasing EG fluorine density, and the resulting PCEs increase from 9 to 16.8%.

Original language	English (US)
Article number	2102172
Journal	Advanced Energy Materials
Volume	12
Issue number	1
DOIs	https://doi.org/10.1002/aenm.202102172
State	Published - Jan 6 2022

Funding

X.Z. and G.L. contributed equally to this work. This work was supported by the US Office of Naval Research Contract N00014‐20‐1‐2116; US Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design Award 70NANB19H005; the Qatar National Research Foundation grant NPRP12S‐0304‐190227/02‐484761; and the P.R.C. Sichuan Province Key Laboratory of Display Science and Technology. The IPDA measurements were supported by the National Science Foundation Materials Research Science and Engineering Center (MRSEC) at Northwestern University (NSF DMR‐1720139). The authors thank the Integrated Molecular Structure Education and Research Center (IMSERC) for characterization facilities supported by Northwestern University, National Science Foundation under NSF CHE‐1048773, Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF NNCI‐1542205), the State of Illinois, and International Institute for Nanotechnology (IIN). 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, Department of Energy under contract no. DE‐AC02‐05CH11231, and at beamline 8‐ID‐E of the Advanced Photon Source, a US 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 work was also sponsored by Sichuan Province Key Laboratory of Display Science and Technology. X.Z. gratefully acknowledges the China Scholarship Council (No. 201906070056) for partial support of this work. Note that certain commercial equipment, instruments, or materials are identified in this paper to specify the experimental procedure adequately. Such identification is not 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

Renewable Energy, Sustainability and the Environment
General Materials Science

UN SDGs

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

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10.1002/aenm.202102172

Cite this

Zhang, X., Li, G., Mukherjee, S., Huang, W., Zheng, D., Feng, L. W., Chen, Y., Wu, J., Sangwan, V. K., Hersam, M. C., DeLongchamp, D. M., Yu, J., Facchetti, A., & Marks, T. J. (2022). Systematically Controlling Acceptor Fluorination Optimizes Hierarchical Morphology, Vertical Phase Separation, and Efficiency in Non-Fullerene Organic Solar Cells. Advanced Energy Materials, 12(1), Article 2102172. https://doi.org/10.1002/aenm.202102172

@article{1d290cf1b2d94826b54d955a07dec1cb,

title = "Systematically Controlling Acceptor Fluorination Optimizes Hierarchical Morphology, Vertical Phase Separation, and Efficiency in Non-Fullerene Organic Solar Cells",

abstract = "Non-fullerene acceptor (NFA) end group (EG) functionalization, especially by fluorination, affects not only the energetics but also the morphology of bulk-heterojunction (BHJ) organic solar cell (OSC) active layers, thereby influencing the power conversion efficiency (PCE) and other metrics of NFA-based OSCs. However, a quantitative understanding of how varying the degrees of NFA fluorination influence the blend morphological and photovoltaic properties remains elusive. Here a series of three A-DAD-A type NFAs (D = π-donor group and A = π-acceptor EG) which systematically increase the degree of EG fluorination and comprehensively investigate the resulting blends with the polymer donor PM6 in terms of optical properties, electronic structure, film crystallinity, charge carrier transport, and OSC performance is reported. The results indicate that the most highly fluorinated NFA, BT-BO-L4F, achieves an optimal BHJ hierarchical morphology where enhanced NFA molecule intermolecular π–π stacking and optimal vertical phase gradation are achieved in the BHJ blend. These factors also promote optimum NFA-cathode contact, more balanced electron and hole mobility, and suppress both monomolecular and bimolecular recombination. As a result, both the short-circuit current density and fill factor in this OSC series progressively increase with increasing EG fluorine density, and the resulting PCEs increase from 9 to 16.8%.",

author = "Xiaohua Zhang and Guoping Li and Subhrangsu Mukherjee and Wei Huang and Ding Zheng and Feng, {Liang Wen} and Yao Chen and Jianglin Wu and Sangwan, {Vinod K.} and Hersam, {Mark C.} and DeLongchamp, {Dean M.} and Junsheng Yu and Antonio Facchetti and Marks, {Tobin J.}",

note = "Funding Information: X.Z. and G.L. contributed equally to this work. This work was supported by the US Office of Naval Research Contract N00014‐20‐1‐2116; US Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design Award 70NANB19H005; the Qatar National Research Foundation grant NPRP12S‐0304‐190227/02‐484761; and the P.R.C. Sichuan Province Key Laboratory of Display Science and Technology. The IPDA measurements were supported by the National Science Foundation Materials Research Science and Engineering Center (MRSEC) at Northwestern University (NSF DMR‐1720139). The authors thank the Integrated Molecular Structure Education and Research Center (IMSERC) for characterization facilities supported by Northwestern University, National Science Foundation under NSF CHE‐1048773, Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF NNCI‐1542205), the State of Illinois, and International Institute for Nanotechnology (IIN). 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, Department of Energy under contract no. DE‐AC02‐05CH11231, and at beamline 8‐ID‐E of the Advanced Photon Source, a US 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 work was also sponsored by Sichuan Province Key Laboratory of Display Science and Technology. X.Z. gratefully acknowledges the China Scholarship Council (No. 201906070056) for partial support of this work. Note that certain commercial equipment, instruments, or materials are identified in this paper to specify the experimental procedure adequately. Such identification is not 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} 2021 Wiley-VCH GmbH.",

year = "2022",

month = jan,

day = "6",

doi = "10.1002/aenm.202102172",

language = "English (US)",

volume = "12",

journal = "Advanced Energy Materials",

issn = "1614-6832",

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Zhang, X, Li, G, Mukherjee, S, Huang, W, Zheng, D, Feng, LW, Chen, Y, Wu, J, Sangwan, VK , Hersam, MC, DeLongchamp, DM, Yu, J, Facchetti, A & Marks, TJ 2022, 'Systematically Controlling Acceptor Fluorination Optimizes Hierarchical Morphology, Vertical Phase Separation, and Efficiency in Non-Fullerene Organic Solar Cells', Advanced Energy Materials, vol. 12, no. 1, 2102172. https://doi.org/10.1002/aenm.202102172

TY - JOUR

T1 - Systematically Controlling Acceptor Fluorination Optimizes Hierarchical Morphology, Vertical Phase Separation, and Efficiency in Non-Fullerene Organic Solar Cells

AU - Zhang, Xiaohua

AU - Li, Guoping

AU - Mukherjee, Subhrangsu

AU - Huang, Wei

AU - Zheng, Ding

AU - Feng, Liang Wen

AU - Chen, Yao

AU - Wu, Jianglin

AU - Sangwan, Vinod K.

AU - Hersam, Mark C.

AU - DeLongchamp, Dean M.

AU - Yu, Junsheng

AU - Facchetti, Antonio

AU - Marks, Tobin J.

N1 - Funding Information: X.Z. and G.L. contributed equally to this work. This work was supported by the US Office of Naval Research Contract N00014‐20‐1‐2116; US Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design Award 70NANB19H005; the Qatar National Research Foundation grant NPRP12S‐0304‐190227/02‐484761; and the P.R.C. Sichuan Province Key Laboratory of Display Science and Technology. The IPDA measurements were supported by the National Science Foundation Materials Research Science and Engineering Center (MRSEC) at Northwestern University (NSF DMR‐1720139). The authors thank the Integrated Molecular Structure Education and Research Center (IMSERC) for characterization facilities supported by Northwestern University, National Science Foundation under NSF CHE‐1048773, Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF NNCI‐1542205), the State of Illinois, and International Institute for Nanotechnology (IIN). 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, Department of Energy under contract no. DE‐AC02‐05CH11231, and at beamline 8‐ID‐E of the Advanced Photon Source, a US 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 work was also sponsored by Sichuan Province Key Laboratory of Display Science and Technology. X.Z. gratefully acknowledges the China Scholarship Council (No. 201906070056) for partial support of this work. Note that certain commercial equipment, instruments, or materials are identified in this paper to specify the experimental procedure adequately. Such identification is not 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: © 2021 Wiley-VCH GmbH.

PY - 2022/1/6

Y1 - 2022/1/6

N2 - Non-fullerene acceptor (NFA) end group (EG) functionalization, especially by fluorination, affects not only the energetics but also the morphology of bulk-heterojunction (BHJ) organic solar cell (OSC) active layers, thereby influencing the power conversion efficiency (PCE) and other metrics of NFA-based OSCs. However, a quantitative understanding of how varying the degrees of NFA fluorination influence the blend morphological and photovoltaic properties remains elusive. Here a series of three A-DAD-A type NFAs (D = π-donor group and A = π-acceptor EG) which systematically increase the degree of EG fluorination and comprehensively investigate the resulting blends with the polymer donor PM6 in terms of optical properties, electronic structure, film crystallinity, charge carrier transport, and OSC performance is reported. The results indicate that the most highly fluorinated NFA, BT-BO-L4F, achieves an optimal BHJ hierarchical morphology where enhanced NFA molecule intermolecular π–π stacking and optimal vertical phase gradation are achieved in the BHJ blend. These factors also promote optimum NFA-cathode contact, more balanced electron and hole mobility, and suppress both monomolecular and bimolecular recombination. As a result, both the short-circuit current density and fill factor in this OSC series progressively increase with increasing EG fluorine density, and the resulting PCEs increase from 9 to 16.8%.

AB - Non-fullerene acceptor (NFA) end group (EG) functionalization, especially by fluorination, affects not only the energetics but also the morphology of bulk-heterojunction (BHJ) organic solar cell (OSC) active layers, thereby influencing the power conversion efficiency (PCE) and other metrics of NFA-based OSCs. However, a quantitative understanding of how varying the degrees of NFA fluorination influence the blend morphological and photovoltaic properties remains elusive. Here a series of three A-DAD-A type NFAs (D = π-donor group and A = π-acceptor EG) which systematically increase the degree of EG fluorination and comprehensively investigate the resulting blends with the polymer donor PM6 in terms of optical properties, electronic structure, film crystallinity, charge carrier transport, and OSC performance is reported. The results indicate that the most highly fluorinated NFA, BT-BO-L4F, achieves an optimal BHJ hierarchical morphology where enhanced NFA molecule intermolecular π–π stacking and optimal vertical phase gradation are achieved in the BHJ blend. These factors also promote optimum NFA-cathode contact, more balanced electron and hole mobility, and suppress both monomolecular and bimolecular recombination. As a result, both the short-circuit current density and fill factor in this OSC series progressively increase with increasing EG fluorine density, and the resulting PCEs increase from 9 to 16.8%.

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Systematically Controlling Acceptor Fluorination Optimizes Hierarchical Morphology, Vertical Phase Separation, and Efficiency in Non-Fullerene Organic Solar Cells

Abstract

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UN SDGs

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CCDC 2068889: Experimental Crystal Structure Determination

CCDC 2068890: Experimental Crystal Structure Determination

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Systematically Controlling Acceptor Fluorination Optimizes Hierarchical Morphology, Vertical Phase Separation, and Efficiency in Non-Fullerene Organic Solar Cells

Abstract

Funding

ASJC Scopus subject areas

UN SDGs

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CCDC 2068889: Experimental Crystal Structure Determination

CCDC 2068890: Experimental Crystal Structure Determination

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