Improved photovoltaic performance of a nonfullerene acceptor based on a benzo[b]thiophene fused end group with extended π-conjugation

Kun Yang, Qiaogan Liao, Chang Woo Koh, Jianhua Chen, Mengyao Su, Xin Zhou, Yumin Tang, Yang Wang, Youming Zhang, Han Young Woo, Xugang Guo

Research output: Contribution to journalArticle

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Abstract

A new indacenodithiophene-based acceptor-donor-acceptor (A-D-A) type nonfullerene acceptor material ITBTC, featuring a conjugation-extended benzo[b]thiophene-fused end group, was designed and synthesized. Compared to the well known phenyl-fused ITIC acceptor containing a 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile (IC) end group, incorporation of an additional electron-rich thiophene into the IC moiety decreased the electron-accepting strength of the end group and increased the intermolecular interactions of ITBTC molecules. As a result, ITBTC exhibited an elevated lowest unoccupied molecular orbital, an improved electron mobility, and a more favorable blend film morphology. Despite its slightly blue-shifted absorption, the photocurrent of ITBTC-based devices was well-maintained due to the extra absorption band in the short wavelength range, which is induced by its conjugation-extended end group. Benefitting from these characteristics, the ITBTC-based solar cells achieved an enhanced power conversion efficiency (PCE) of 10.99% with a simultaneously improved open-circuit voltage (V oc , 0.94 V) and fill factor (FF, 71.3%) and well-maintained short-circuit current density (J sc , 16.37 mA cm −2 ), compared to those of the ITIC-based devices (PCE of 9.53%). These results suggest that extending the π-conjugation of end group through thiophene incorporation is an efficient approach for optimizing both the energy level alignment and intermolecular interaction of the acceptor materials while maintaining their efficient light-harvesting ability. Our study also demonstrates the great potential of the new benzo[b]thiophene-fused end group for constructing high-performance nonfullerene acceptors and provided insight into overcoming the trade-off between J sc and V oc to realize simultaneously enhanced photovoltaic parameters.

Original languageEnglish
Pages (from-to)9822-9830
Number of pages9
JournalJournal of Materials Chemistry A
Volume7
Issue number16
DOIs
Publication statusPublished - 2019 Jan 1

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Thiophenes
Thiophene
Conversion efficiency
Electrons
Electron mobility
Molecular orbitals
Open circuit voltage
Photocurrents
Short circuit currents
Electron energy levels
Absorption spectra
Solar cells
Current density
Wavelength
Molecules
benzothiophene
dicyanmethane

ASJC Scopus subject areas

  • Chemistry(all)
  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

Cite this

Improved photovoltaic performance of a nonfullerene acceptor based on a benzo[b]thiophene fused end group with extended π-conjugation. / Yang, Kun; Liao, Qiaogan; Koh, Chang Woo; Chen, Jianhua; Su, Mengyao; Zhou, Xin; Tang, Yumin; Wang, Yang; Zhang, Youming; Woo, Han Young; Guo, Xugang.

In: Journal of Materials Chemistry A, Vol. 7, No. 16, 01.01.2019, p. 9822-9830.

Research output: Contribution to journalArticle

Yang, Kun ; Liao, Qiaogan ; Koh, Chang Woo ; Chen, Jianhua ; Su, Mengyao ; Zhou, Xin ; Tang, Yumin ; Wang, Yang ; Zhang, Youming ; Woo, Han Young ; Guo, Xugang. / Improved photovoltaic performance of a nonfullerene acceptor based on a benzo[b]thiophene fused end group with extended π-conjugation. In: Journal of Materials Chemistry A. 2019 ; Vol. 7, No. 16. pp. 9822-9830.
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abstract = "A new indacenodithiophene-based acceptor-donor-acceptor (A-D-A) type nonfullerene acceptor material ITBTC, featuring a conjugation-extended benzo[b]thiophene-fused end group, was designed and synthesized. Compared to the well known phenyl-fused ITIC acceptor containing a 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile (IC) end group, incorporation of an additional electron-rich thiophene into the IC moiety decreased the electron-accepting strength of the end group and increased the intermolecular interactions of ITBTC molecules. As a result, ITBTC exhibited an elevated lowest unoccupied molecular orbital, an improved electron mobility, and a more favorable blend film morphology. Despite its slightly blue-shifted absorption, the photocurrent of ITBTC-based devices was well-maintained due to the extra absorption band in the short wavelength range, which is induced by its conjugation-extended end group. Benefitting from these characteristics, the ITBTC-based solar cells achieved an enhanced power conversion efficiency (PCE) of 10.99{\%} with a simultaneously improved open-circuit voltage (V oc , 0.94 V) and fill factor (FF, 71.3{\%}) and well-maintained short-circuit current density (J sc , 16.37 mA cm −2 ), compared to those of the ITIC-based devices (PCE of 9.53{\%}). These results suggest that extending the π-conjugation of end group through thiophene incorporation is an efficient approach for optimizing both the energy level alignment and intermolecular interaction of the acceptor materials while maintaining their efficient light-harvesting ability. Our study also demonstrates the great potential of the new benzo[b]thiophene-fused end group for constructing high-performance nonfullerene acceptors and provided insight into overcoming the trade-off between J sc and V oc to realize simultaneously enhanced photovoltaic parameters.",
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AU - Su, Mengyao

AU - Zhou, Xin

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AU - Wang, Yang

AU - Zhang, Youming

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