Closely packed, low reorganization energy π-extended postfullerene acceptors for efficient polymer solar cells

Steven M. Swick, Weigang Zhu, Micaela Matta, Thomas J. Aldrich, Alexandra Harbuzaru, J. Teodomiro Lopez Navarrete, Rocio Ponce Ortiz, Kevin L. Kohlstedt, George C Schatz, Antonio Facchetti, Ferdinand S. Melkonyan, Tobin J Marks

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

New organic semiconductors are essential for developing inexpensive, high-efficiency, solution-processable polymer solar cells (PSCs). PSC photoactive layers are typically fabricated by film-casting a donor polymer and a fullerene acceptor blend, with ensuing solvent evaporation and phase separation creating discrete conduits for photogenerated holes and electrons. Until recently, n-type fullerene acceptors dominated the PSC literature; however, indacenodithienothiophene (IDTT)-based acceptors have recently enabled remarkable PSC performance metrics, for reasons that are not entirely obvious. We report two isomeric IDTT-based acceptors 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-benz-(5, 6)indanone))-5,5,11,11-tetrakis(4-nonylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]di-thiophene (ITN-C9) and 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-benz(6,7)indanone))-5,5,11,11-tetrakis (4-nonylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithio-phene (ITzN-C9) that shed light on the exceptional IDTT properties vis-à-vis fullerenes. The neat acceptors and blends with fluoropolymer donor poly{[4,8-bis[5-(2- ethylhexyl)-4-fluoro-2-thienyl]benzo[1,2-b:4,5-b′]dithiophene2,6-diyl]-alt-[2,5-thiophenediyl[5,7-bis(2-ethylhexyl)-4,8-dioxo4H,8H-benzo[1,2-c:4,5-c′]dithiophene-1,3-diyl]]} (PBDB-TF) are investigated by optical spectroscopy, cyclic voltammetry, thermogravimetric analysis, differential scanning calorimetry, single-crystal X-ray diffraction, photovoltaic response, space-charge-limited current transport, atomic force microscopy, grazing incidence wide-angle X-ray scattering, and density functional theory-level quantum chemical analysis. The data reveal that ITN-C9 and ITzN-C9 organize such that the lowest unoccupied molecular orbital-rich end groups have intermolecular π−π distances as close as 3.31(1) Å, with electronic coupling integrals as large as 38 meV, and internal reorganization energies as small as 0.133 eV, comparable to or superior to those in fullerenes. ITN-C9 and ITzN-C9 have broad solar-relevant optical absorption, and, when blended with PBDB-TF, afford devices with power conversion efficiencies near 10%. Performance differences between ITN-C9 and ITzN-C9 are understandable in terms of molecular and electronic structure distinctions via the influences on molecular packing and orientation with respect to the electrode.

Original languageEnglish
Pages (from-to)E8341-E8348
JournalProceedings of the National Academy of Sciences of the United States of America
Volume115
Issue number36
DOIs
Publication statusPublished - Sep 4 2018

Fingerprint

Fullerenes
Thiophenes
Fluorine containing polymers
Semiconducting organic compounds
Molecular orbitals
X ray scattering
Electric space charge
Phase separation
Light absorption
Molecular structure
Conversion efficiency
Cyclic voltammetry
Electronic structure
Density functional theory
Thermogravimetric analysis
Differential scanning calorimetry
Atomic force microscopy
Polymers
Casting
Evaporation

Keywords

  • Molecular modeling
  • Or anic hotovoltaic
  • Single crystal
  • Small molecule acceptor
  • Solar energy

ASJC Scopus subject areas

  • General

Cite this

Closely packed, low reorganization energy π-extended postfullerene acceptors for efficient polymer solar cells. / Swick, Steven M.; Zhu, Weigang; Matta, Micaela; Aldrich, Thomas J.; Harbuzaru, Alexandra; Navarrete, J. Teodomiro Lopez; Ortiz, Rocio Ponce; Kohlstedt, Kevin L.; Schatz, George C; Facchetti, Antonio; Melkonyan, Ferdinand S.; Marks, Tobin J.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 115, No. 36, 04.09.2018, p. E8341-E8348.

Research output: Contribution to journalArticle

Swick, SM, Zhu, W, Matta, M, Aldrich, TJ, Harbuzaru, A, Navarrete, JTL, Ortiz, RP, Kohlstedt, KL, Schatz, GC, Facchetti, A, Melkonyan, FS & Marks, TJ 2018, 'Closely packed, low reorganization energy π-extended postfullerene acceptors for efficient polymer solar cells', Proceedings of the National Academy of Sciences of the United States of America, vol. 115, no. 36, pp. E8341-E8348. https://doi.org/10.1073/pnas.1807535115
Swick, Steven M. ; Zhu, Weigang ; Matta, Micaela ; Aldrich, Thomas J. ; Harbuzaru, Alexandra ; Navarrete, J. Teodomiro Lopez ; Ortiz, Rocio Ponce ; Kohlstedt, Kevin L. ; Schatz, George C ; Facchetti, Antonio ; Melkonyan, Ferdinand S. ; Marks, Tobin J. / Closely packed, low reorganization energy π-extended postfullerene acceptors for efficient polymer solar cells. In: Proceedings of the National Academy of Sciences of the United States of America. 2018 ; Vol. 115, No. 36. pp. E8341-E8348.
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T1 - Closely packed, low reorganization energy π-extended postfullerene acceptors for efficient polymer solar cells

AU - Swick, Steven M.

AU - Zhu, Weigang

AU - Matta, Micaela

AU - Aldrich, Thomas J.

AU - Harbuzaru, Alexandra

AU - Navarrete, J. Teodomiro Lopez

AU - Ortiz, Rocio Ponce

AU - Kohlstedt, Kevin L.

AU - Schatz, George C

AU - Facchetti, Antonio

AU - Melkonyan, Ferdinand S.

AU - Marks, Tobin J

PY - 2018/9/4

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N2 - New organic semiconductors are essential for developing inexpensive, high-efficiency, solution-processable polymer solar cells (PSCs). PSC photoactive layers are typically fabricated by film-casting a donor polymer and a fullerene acceptor blend, with ensuing solvent evaporation and phase separation creating discrete conduits for photogenerated holes and electrons. Until recently, n-type fullerene acceptors dominated the PSC literature; however, indacenodithienothiophene (IDTT)-based acceptors have recently enabled remarkable PSC performance metrics, for reasons that are not entirely obvious. We report two isomeric IDTT-based acceptors 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-benz-(5, 6)indanone))-5,5,11,11-tetrakis(4-nonylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]di-thiophene (ITN-C9) and 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-benz(6,7)indanone))-5,5,11,11-tetrakis (4-nonylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithio-phene (ITzN-C9) that shed light on the exceptional IDTT properties vis-à-vis fullerenes. The neat acceptors and blends with fluoropolymer donor poly{[4,8-bis[5-(2- ethylhexyl)-4-fluoro-2-thienyl]benzo[1,2-b:4,5-b′]dithiophene2,6-diyl]-alt-[2,5-thiophenediyl[5,7-bis(2-ethylhexyl)-4,8-dioxo4H,8H-benzo[1,2-c:4,5-c′]dithiophene-1,3-diyl]]} (PBDB-TF) are investigated by optical spectroscopy, cyclic voltammetry, thermogravimetric analysis, differential scanning calorimetry, single-crystal X-ray diffraction, photovoltaic response, space-charge-limited current transport, atomic force microscopy, grazing incidence wide-angle X-ray scattering, and density functional theory-level quantum chemical analysis. The data reveal that ITN-C9 and ITzN-C9 organize such that the lowest unoccupied molecular orbital-rich end groups have intermolecular π−π distances as close as 3.31(1) Å, with electronic coupling integrals as large as 38 meV, and internal reorganization energies as small as 0.133 eV, comparable to or superior to those in fullerenes. ITN-C9 and ITzN-C9 have broad solar-relevant optical absorption, and, when blended with PBDB-TF, afford devices with power conversion efficiencies near 10%. Performance differences between ITN-C9 and ITzN-C9 are understandable in terms of molecular and electronic structure distinctions via the influences on molecular packing and orientation with respect to the electrode.

AB - New organic semiconductors are essential for developing inexpensive, high-efficiency, solution-processable polymer solar cells (PSCs). PSC photoactive layers are typically fabricated by film-casting a donor polymer and a fullerene acceptor blend, with ensuing solvent evaporation and phase separation creating discrete conduits for photogenerated holes and electrons. Until recently, n-type fullerene acceptors dominated the PSC literature; however, indacenodithienothiophene (IDTT)-based acceptors have recently enabled remarkable PSC performance metrics, for reasons that are not entirely obvious. We report two isomeric IDTT-based acceptors 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-benz-(5, 6)indanone))-5,5,11,11-tetrakis(4-nonylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]di-thiophene (ITN-C9) and 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-benz(6,7)indanone))-5,5,11,11-tetrakis (4-nonylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithio-phene (ITzN-C9) that shed light on the exceptional IDTT properties vis-à-vis fullerenes. The neat acceptors and blends with fluoropolymer donor poly{[4,8-bis[5-(2- ethylhexyl)-4-fluoro-2-thienyl]benzo[1,2-b:4,5-b′]dithiophene2,6-diyl]-alt-[2,5-thiophenediyl[5,7-bis(2-ethylhexyl)-4,8-dioxo4H,8H-benzo[1,2-c:4,5-c′]dithiophene-1,3-diyl]]} (PBDB-TF) are investigated by optical spectroscopy, cyclic voltammetry, thermogravimetric analysis, differential scanning calorimetry, single-crystal X-ray diffraction, photovoltaic response, space-charge-limited current transport, atomic force microscopy, grazing incidence wide-angle X-ray scattering, and density functional theory-level quantum chemical analysis. The data reveal that ITN-C9 and ITzN-C9 organize such that the lowest unoccupied molecular orbital-rich end groups have intermolecular π−π distances as close as 3.31(1) Å, with electronic coupling integrals as large as 38 meV, and internal reorganization energies as small as 0.133 eV, comparable to or superior to those in fullerenes. ITN-C9 and ITzN-C9 have broad solar-relevant optical absorption, and, when blended with PBDB-TF, afford devices with power conversion efficiencies near 10%. Performance differences between ITN-C9 and ITzN-C9 are understandable in terms of molecular and electronic structure distinctions via the influences on molecular packing and orientation with respect to the electrode.

KW - Molecular modeling

KW - Or anic hotovoltaic

KW - Single crystal

KW - Small molecule acceptor

KW - Solar energy

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