Abstract
The synthesis and characterization of new semiconducting materials is essential for developing high-efficiency organic solar cells. Here, the synthesis, physiochemical properties, thin film morphology, and photovoltaic response of ITN-F4 and ITzN-F4, the first indacenodithienothiophene nonfullerene acceptors that combine π-extension and fluorination, are reported. The neat acceptors and bulk-heterojunction blend films with fluorinated donor polymer poly{[4,8-bis[5-(2-ethylhexyl)-4-fluoro-2-thienyl]benzo[1,2-b:4,5-b′]-dithiophene-2,6-diyl]-alt-[2,5-thiophenediyl[5,7-bis(2-ethylhexyl)-4,8-dioxo-4H,8H-benzo[1,2-c:4,5-c′]dithiophene-1,3-diyl]]} (PBDB-TF, also known as PM6) are investigated using a battery of techniques, including single crystal X-ray diffraction, fs transient absorption spectroscopy (fsTA), photovoltaic response, space-charge-limited current transport, impedance spectroscopy, grazing incidence wide angle X-ray scattering, and density functional theory level computation. ITN-F4 and ITzN-F4 are found to provide power conversion efficiencies greater and internal reorganization energies less than their non-π-extended and nonfluorinated counterparts when paired with PBDB-TF. Additionally, ITN-F4 and ITzN-F4 exhibit favorable bulk-heterojunction relevant single crystal packing architectures. fsTA reveals that both ITN-F4 and ITzN-F4 undergo ultrafast hole transfer (<300 fs) in films with PBDB-TF, despite excimer state formation in both the neat and blend films. Taken together and in comparison to related structures, these results demonstrate that combined fluorination and π-extension synergistically promote crystallographic π-face-to-face packing, increase crystallinity, reduce internal reorganization energies, increase interplanar π–π electronic coupling, and increase power conversion efficiency.
Original language | English (US) |
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Article number | 2000635 |
Journal | Advanced Energy Materials |
Volume | 10 |
Issue number | 23 |
DOIs | |
State | Published - Jun 1 2020 |
Funding
This research was supported by 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 No. DE‐SC0001059. S.M.S. thanks the NSF for a Predoctoral Fellowship. This research was supported by 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 No. DE-SC0001059. S.M.S. thanks the NSF for a Predoctoral Fellowship.
Keywords
- computational chemistry
- crystal structures
- femtosecond transient absorption spectroscopy
- impedance spectroscopy
- organic solar cells
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- General Materials Science
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CCDC 1980790: Experimental Crystal Structure Determination
Swick, S. M. (Contributor), Alzola, J. M. (Contributor), Sangwan, V. K. (Contributor), Amsterdam, S. H. (Contributor), Zhu, W. (Contributor), Jones, L. O. (Contributor), Powers-Riggs, N. (Contributor), Facchetti, A. (Contributor), Kohlstedt, K. L. (Contributor), Schatz, G. C. (Contributor), Hersam, M. C. (Contributor), Wasielewski, M. R. (Contributor) & Marks, T. J. (Contributor), Cambridge Crystallographic Data Centre, 2021
DOI: 10.5517/ccdc.csd.cc24h5g9, http://www.ccdc.cam.ac.uk/services/structure_request?id=doi:10.5517/ccdc.csd.cc24h5g9&sid=DataCite
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CCDC 1980791: Experimental Crystal Structure Determination
Swick, S. M. (Contributor), Alzola, J. M. (Contributor), Sangwan, V. K. (Contributor), Amsterdam, S. H. (Contributor), Zhu, W. (Contributor), Jones, L. O. (Contributor), Powers-Riggs, N. (Contributor), Facchetti, A. (Contributor), Kohlstedt, K. L. (Contributor), Schatz, G. C. (Contributor), Hersam, M. C. (Contributor), Wasielewski, M. R. (Contributor) & Marks, T. J. (Contributor), Cambridge Crystallographic Data Centre, 2021
DOI: 10.5517/ccdc.csd.cc24h5hb, http://www.ccdc.cam.ac.uk/services/structure_request?id=doi:10.5517/ccdc.csd.cc24h5hb&sid=DataCite
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