Journal of Energy Chemistry ›› 2022, Vol. 64 ›› Issue (1): 236-245.DOI: 10.1016/j.jechem.2021.04.032

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High-efficiency single and tandem fullerene solar cells with asymmetric monofluorinated diketopyrrolopyrrole-based polymer

Shafket Rasoola,b,1, Quoc Viet Hoanga,c,1, Doan Van Vua, Chang Eun Songa,b,*, Hang Ken Leea, Sang Kyu Leea,b, Jong-Cheol Leea,b, Sang-Jin Moona,b, Won Suk Shina,b,*   

  1. aEnergy Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong, Daejeon 34114, Republic of Korea;
    bAdvanced Materials and Chemical Engineering, University of Science and Technology (UST), 217 Gajeongro, Yuseong, Daejeon 34113, Republic of Korea;
    cVietnam Standards and Quality Institute (VSQI), Directorate for Standards, Metrology and Quality (STAMEQ), No.8, Hoang Quoc Viet, Cau Giay, Hanoi, Viet Nam
  • Received:2021-02-07 Revised:2021-04-14 Accepted:2021-04-16 Online:2022-01-15 Published:2022-10-28
  • Contact: *E-mail addresses: songce@krict.re.kr (C.E. Song), shinws@krict.re.kr (W.S. Shin).
  • About author:1 These authors contributed equally to this work.

Abstract: Design and synthesis of low bandgap (LBG) polymer donors is inevitably challenging and their process-ability from a non-halogenated solvent system remains a hurdle to overcome in the area of high-performance polymer solar cells (PSCs). Due to a high aggregation tendency of LBG polymers, especially diketopyrrolopyrrole (DPP) -based polymers coupled with bithiophenes in the polymer backbones, their widespread adoption in non-halogenated solvent-processed PSCs has been limited. Herein, a novel LBG DPP-based polymer, called PDPP4T-1F with asymmetric arrangement of fluorine atom, has been success-fully synthesized and showed an outstanding power conversion efficiency (PCE) of 10.10% in a single-junction fullerene-based PSCs. Furthermore, an impressive PCE of 13.21% has been achieved in a tandem device from a fully non-halogenated solvent system, which integrates a wide bandgap PDTBTBz-2F poly-mer in the bottom cell and LBG PDPP4T-1F polymer in the top cell. The achieved efficiency is the highest value reported in the literature to date in fullerene-based tandem PSCs. We found that a uniformly dis-tributed interpenetrating fibril network with nano-scale phase separation and anisotropy of the polymer backbone orientation for efficient charge transfer/transport and suppressed charge recombination in PDPP4T-1F-based PSCs led to outstanding PCEs in single and tandem-junction PSCs.

Key words: Low bandgap polymers, Diketopyrrolopyrrole, Tandem polymer solar cells, Non-halogenated solvent, Monofluoro-bithiophene