Quinoxaline-Based Wide Band Gap Polymers for Efficient Nonfullerene Organic Solar Cells with Large Open-Circuit Voltages

Jie Yang, Mohammad Afsar Uddin, Yumin Tang, Yulun Wang, Yang Wang, Huimin Su, Rutian Gao, Zhi Kuan Chen, Junfeng Dai, Han Young Woo, Xugang Guo

Research output: Contribution to journalArticle

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Abstract

We present here a series of wide-band-gap (E g : >1.8 eV) polymer donors by incorporating thiophene-flanked phenylene as an electron-donating unit and quinoxaline as an electron-Accepting co-unit to attain large open-circuit voltages (V oc s) and short-circuit currents (J sc s) in nonfullerene organic solar cells (OSCs). Fluorination was utilized to fine-Tailor the energetics of polymer frontier molecular orbitals (FMOs) by replacing a variable number of H atoms on the phenylene moiety with F. It was found that fluorination can effectively modulate the polymer backbone planarity through intramolecular noncovalent S···F and/or H···F interactions. Polymers (P2-P4) show an improved molecular packing with a favorable face-on orientation compared to their nonfluorinated analogue (P1), which is critical to charge carrier transport and collection. When mixed with IDIC, a nonfullerene acceptor, P3 with two F atoms, achieves a remarkable V oc of 1.00 V and a large J sc of 15.99 mA/cm 2 , simultaneously, yielding a power-conversion efficiency (PCE) of 9.7%. Notably, the 1.00 V V oc is among the largest values in the IDIC-based OSCs, leading to a small energy loss (E loss : 0.62 eV) while maintaining a large PCE. The P3:IDIC blend shows an efficient exciton dissociation through hole transfer even under a small energy offset of 0.16 eV. Further fluorination leads to the polymer P4 with increased chain-Twisting and mismatched FMO levels with IDIC, showing the lowest PCE of 2.93%. The results demonstrate that quinoxaline-based copolymers are promising donors for efficient OSCs and the fluorination needs to be fine-Adjusted to optimize the interchain packing and physicochemical properties of polymers. Additionally, the structure-property correlations from this work provide useful insights for developing wide-band-gap polymers with low-lying highest occupied molecular orbitals to minimize E loss and maximize V oc in nonfullerene OSCs for efficient power conversion.

Original languageEnglish
Pages (from-to)23235-23246
Number of pages12
JournalACS Applied Materials and Interfaces
Volume10
Issue number27
DOIs
Publication statusPublished - 2018 Jul 11

Fingerprint

Quinoxalines
Open circuit voltage
Polymers
Energy gap
Fluorination
Molecular orbitals
Conversion efficiency
Thiophenes
Atoms
Carrier transport
Electrons
Thiophene
Organic solar cells
Charge carriers
Excitons
Short circuit currents
Energy dissipation
Copolymers

Keywords

  • energy losses
  • fluorination
  • nonfullerene organic solar cells
  • open-circuit voltages
  • polymer semiconductors

ASJC Scopus subject areas

  • Materials Science(all)

Cite this

Quinoxaline-Based Wide Band Gap Polymers for Efficient Nonfullerene Organic Solar Cells with Large Open-Circuit Voltages. / Yang, Jie; Uddin, Mohammad Afsar; Tang, Yumin; Wang, Yulun; Wang, Yang; Su, Huimin; Gao, Rutian; Chen, Zhi Kuan; Dai, Junfeng; Woo, Han Young; Guo, Xugang.

In: ACS Applied Materials and Interfaces, Vol. 10, No. 27, 11.07.2018, p. 23235-23246.

Research output: Contribution to journalArticle

Yang, Jie ; Uddin, Mohammad Afsar ; Tang, Yumin ; Wang, Yulun ; Wang, Yang ; Su, Huimin ; Gao, Rutian ; Chen, Zhi Kuan ; Dai, Junfeng ; Woo, Han Young ; Guo, Xugang. / Quinoxaline-Based Wide Band Gap Polymers for Efficient Nonfullerene Organic Solar Cells with Large Open-Circuit Voltages. In: ACS Applied Materials and Interfaces. 2018 ; Vol. 10, No. 27. pp. 23235-23246.
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abstract = "We present here a series of wide-band-gap (E g : >1.8 eV) polymer donors by incorporating thiophene-flanked phenylene as an electron-donating unit and quinoxaline as an electron-Accepting co-unit to attain large open-circuit voltages (V oc s) and short-circuit currents (J sc s) in nonfullerene organic solar cells (OSCs). Fluorination was utilized to fine-Tailor the energetics of polymer frontier molecular orbitals (FMOs) by replacing a variable number of H atoms on the phenylene moiety with F. It was found that fluorination can effectively modulate the polymer backbone planarity through intramolecular noncovalent S···F and/or H···F interactions. Polymers (P2-P4) show an improved molecular packing with a favorable face-on orientation compared to their nonfluorinated analogue (P1), which is critical to charge carrier transport and collection. When mixed with IDIC, a nonfullerene acceptor, P3 with two F atoms, achieves a remarkable V oc of 1.00 V and a large J sc of 15.99 mA/cm 2 , simultaneously, yielding a power-conversion efficiency (PCE) of 9.7{\%}. Notably, the 1.00 V V oc is among the largest values in the IDIC-based OSCs, leading to a small energy loss (E loss : 0.62 eV) while maintaining a large PCE. The P3:IDIC blend shows an efficient exciton dissociation through hole transfer even under a small energy offset of 0.16 eV. Further fluorination leads to the polymer P4 with increased chain-Twisting and mismatched FMO levels with IDIC, showing the lowest PCE of 2.93{\%}. The results demonstrate that quinoxaline-based copolymers are promising donors for efficient OSCs and the fluorination needs to be fine-Adjusted to optimize the interchain packing and physicochemical properties of polymers. Additionally, the structure-property correlations from this work provide useful insights for developing wide-band-gap polymers with low-lying highest occupied molecular orbitals to minimize E loss and maximize V oc in nonfullerene OSCs for efficient power conversion.",
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AU - Tang, Yumin

AU - Wang, Yulun

AU - Wang, Yang

AU - Su, Huimin

AU - Gao, Rutian

AU - Chen, Zhi Kuan

AU - Dai, Junfeng

AU - Woo, Han Young

AU - Guo, Xugang

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N2 - We present here a series of wide-band-gap (E g : >1.8 eV) polymer donors by incorporating thiophene-flanked phenylene as an electron-donating unit and quinoxaline as an electron-Accepting co-unit to attain large open-circuit voltages (V oc s) and short-circuit currents (J sc s) in nonfullerene organic solar cells (OSCs). Fluorination was utilized to fine-Tailor the energetics of polymer frontier molecular orbitals (FMOs) by replacing a variable number of H atoms on the phenylene moiety with F. It was found that fluorination can effectively modulate the polymer backbone planarity through intramolecular noncovalent S···F and/or H···F interactions. Polymers (P2-P4) show an improved molecular packing with a favorable face-on orientation compared to their nonfluorinated analogue (P1), which is critical to charge carrier transport and collection. When mixed with IDIC, a nonfullerene acceptor, P3 with two F atoms, achieves a remarkable V oc of 1.00 V and a large J sc of 15.99 mA/cm 2 , simultaneously, yielding a power-conversion efficiency (PCE) of 9.7%. Notably, the 1.00 V V oc is among the largest values in the IDIC-based OSCs, leading to a small energy loss (E loss : 0.62 eV) while maintaining a large PCE. The P3:IDIC blend shows an efficient exciton dissociation through hole transfer even under a small energy offset of 0.16 eV. Further fluorination leads to the polymer P4 with increased chain-Twisting and mismatched FMO levels with IDIC, showing the lowest PCE of 2.93%. The results demonstrate that quinoxaline-based copolymers are promising donors for efficient OSCs and the fluorination needs to be fine-Adjusted to optimize the interchain packing and physicochemical properties of polymers. Additionally, the structure-property correlations from this work provide useful insights for developing wide-band-gap polymers with low-lying highest occupied molecular orbitals to minimize E loss and maximize V oc in nonfullerene OSCs for efficient power conversion.

AB - We present here a series of wide-band-gap (E g : >1.8 eV) polymer donors by incorporating thiophene-flanked phenylene as an electron-donating unit and quinoxaline as an electron-Accepting co-unit to attain large open-circuit voltages (V oc s) and short-circuit currents (J sc s) in nonfullerene organic solar cells (OSCs). Fluorination was utilized to fine-Tailor the energetics of polymer frontier molecular orbitals (FMOs) by replacing a variable number of H atoms on the phenylene moiety with F. It was found that fluorination can effectively modulate the polymer backbone planarity through intramolecular noncovalent S···F and/or H···F interactions. Polymers (P2-P4) show an improved molecular packing with a favorable face-on orientation compared to their nonfluorinated analogue (P1), which is critical to charge carrier transport and collection. When mixed with IDIC, a nonfullerene acceptor, P3 with two F atoms, achieves a remarkable V oc of 1.00 V and a large J sc of 15.99 mA/cm 2 , simultaneously, yielding a power-conversion efficiency (PCE) of 9.7%. Notably, the 1.00 V V oc is among the largest values in the IDIC-based OSCs, leading to a small energy loss (E loss : 0.62 eV) while maintaining a large PCE. The P3:IDIC blend shows an efficient exciton dissociation through hole transfer even under a small energy offset of 0.16 eV. Further fluorination leads to the polymer P4 with increased chain-Twisting and mismatched FMO levels with IDIC, showing the lowest PCE of 2.93%. The results demonstrate that quinoxaline-based copolymers are promising donors for efficient OSCs and the fluorination needs to be fine-Adjusted to optimize the interchain packing and physicochemical properties of polymers. Additionally, the structure-property correlations from this work provide useful insights for developing wide-band-gap polymers with low-lying highest occupied molecular orbitals to minimize E loss and maximize V oc in nonfullerene OSCs for efficient power conversion.

KW - energy losses

KW - fluorination

KW - nonfullerene organic solar cells

KW - open-circuit voltages

KW - polymer semiconductors

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