Incorporating Fluorine Substitution into Conjugated Polymers for Solar Cells

Three Different Means, Same Results

Mary Allison Kelly, Steffen Roland, Qianqian Zhang, Youngmin Lee, Bernd C. Kabius, Qing Wang, Enrique Daniel Gomez, Dieter Neher, Wei You

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Fluorinating conjugated polymers is a proven strategy for creating high performance materials in polymer solar cells, yet few studies have investigated the importance of the fluorination method. We compare the performance of three fluorinated systems: a poly(benzodithieno-dithienyltriazole) (PBnDT-XTAZ) random copolymer where 50% of the acceptor units are difluorinated, PBnDT-mFTAZ where every acceptor unit is monofluorinated, and a 1:1 physical blend of the difluorinated and nonfluorinated polymer. All systems have the same degree of fluorination (50%) yet via different methods (chemically vs physically, random vs regular). We show that these three systems have equivalent photovoltaic behavior: ∼5.2% efficiency with a short-circuit current (Jsc) at ∼11 mA cm-2, an open-circuit voltage (Voc) at 0.77 V, and a fill factor (FF) of ∼60%. Further investigation of these three systems demonstrates that the charge generation, charge extraction, and charge transfer state are essentially identical for the three studied systems. Transmission electron microscopy shows no significant differences in the morphologies. All these data illustrate that it is possible to improve performance not only via regular or random fluorination but also by physical addition via a ternary blend. Thus, our results demonstrate the versatility of incorporating fluorine in the active layer of polymer solar cells to enhance device performance. (Graph Presented).

Original languageEnglish (US)
Pages (from-to)2059-2068
Number of pages10
JournalJournal of Physical Chemistry C
Volume121
Issue number4
DOIs
StatePublished - Feb 2 2017

Fingerprint

Fluorination
Fluorine
Conjugated polymers
fluorination
fluorine
Solar cells
Substitution reactions
solar cells
substitutes
polymers
Open circuit voltage
Short circuit currents
Charge transfer
Polymers
versatility
short circuit currents
Copolymers
open circuit voltage
Transmission electron microscopy
copolymers

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

Cite this

Kelly, Mary Allison ; Roland, Steffen ; Zhang, Qianqian ; Lee, Youngmin ; Kabius, Bernd C. ; Wang, Qing ; Gomez, Enrique Daniel ; Neher, Dieter ; You, Wei. / Incorporating Fluorine Substitution into Conjugated Polymers for Solar Cells : Three Different Means, Same Results. In: Journal of Physical Chemistry C. 2017 ; Vol. 121, No. 4. pp. 2059-2068.
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abstract = "Fluorinating conjugated polymers is a proven strategy for creating high performance materials in polymer solar cells, yet few studies have investigated the importance of the fluorination method. We compare the performance of three fluorinated systems: a poly(benzodithieno-dithienyltriazole) (PBnDT-XTAZ) random copolymer where 50{\%} of the acceptor units are difluorinated, PBnDT-mFTAZ where every acceptor unit is monofluorinated, and a 1:1 physical blend of the difluorinated and nonfluorinated polymer. All systems have the same degree of fluorination (50{\%}) yet via different methods (chemically vs physically, random vs regular). We show that these three systems have equivalent photovoltaic behavior: ∼5.2{\%} efficiency with a short-circuit current (Jsc) at ∼11 mA cm-2, an open-circuit voltage (Voc) at 0.77 V, and a fill factor (FF) of ∼60{\%}. Further investigation of these three systems demonstrates that the charge generation, charge extraction, and charge transfer state are essentially identical for the three studied systems. Transmission electron microscopy shows no significant differences in the morphologies. All these data illustrate that it is possible to improve performance not only via regular or random fluorination but also by physical addition via a ternary blend. Thus, our results demonstrate the versatility of incorporating fluorine in the active layer of polymer solar cells to enhance device performance. (Graph Presented).",
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Incorporating Fluorine Substitution into Conjugated Polymers for Solar Cells : Three Different Means, Same Results. / Kelly, Mary Allison; Roland, Steffen; Zhang, Qianqian; Lee, Youngmin; Kabius, Bernd C.; Wang, Qing; Gomez, Enrique Daniel; Neher, Dieter; You, Wei.

In: Journal of Physical Chemistry C, Vol. 121, No. 4, 02.02.2017, p. 2059-2068.

Research output: Contribution to journalArticle

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AU - Kelly, Mary Allison

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AB - Fluorinating conjugated polymers is a proven strategy for creating high performance materials in polymer solar cells, yet few studies have investigated the importance of the fluorination method. We compare the performance of three fluorinated systems: a poly(benzodithieno-dithienyltriazole) (PBnDT-XTAZ) random copolymer where 50% of the acceptor units are difluorinated, PBnDT-mFTAZ where every acceptor unit is monofluorinated, and a 1:1 physical blend of the difluorinated and nonfluorinated polymer. All systems have the same degree of fluorination (50%) yet via different methods (chemically vs physically, random vs regular). We show that these three systems have equivalent photovoltaic behavior: ∼5.2% efficiency with a short-circuit current (Jsc) at ∼11 mA cm-2, an open-circuit voltage (Voc) at 0.77 V, and a fill factor (FF) of ∼60%. Further investigation of these three systems demonstrates that the charge generation, charge extraction, and charge transfer state are essentially identical for the three studied systems. Transmission electron microscopy shows no significant differences in the morphologies. All these data illustrate that it is possible to improve performance not only via regular or random fluorination but also by physical addition via a ternary blend. Thus, our results demonstrate the versatility of incorporating fluorine in the active layer of polymer solar cells to enhance device performance. (Graph Presented).

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