Molecular engineering of conjugated polymers for solar cells and field-effect transistors: Side-chain versus main-chain electron acceptors

Authors

  • Dong Wook Chang,

    1. Interdisciplinary School of Green Energy/Institute of Advanced Materials and Devices, Ulsan National Institute of Science and Technology, Banyeon, Ulsan 689-798, South Korea
    Search for more papers by this author
  • Seo-Jin Ko,

    1. Interdisciplinary School of Green Energy/Institute of Advanced Materials and Devices, Ulsan National Institute of Science and Technology, Banyeon, Ulsan 689-798, South Korea
    Search for more papers by this author
  • Gi-Hwan Kim,

    1. Interdisciplinary School of Green Energy/Institute of Advanced Materials and Devices, Ulsan National Institute of Science and Technology, Banyeon, Ulsan 689-798, South Korea
    Search for more papers by this author
  • Seo-Yoon Bae,

    1. Interdisciplinary School of Green Energy/Institute of Advanced Materials and Devices, Ulsan National Institute of Science and Technology, Banyeon, Ulsan 689-798, South Korea
    Search for more papers by this author
  • Jin Young Kim,

    Corresponding author
    1. Interdisciplinary School of Green Energy/Institute of Advanced Materials and Devices, Ulsan National Institute of Science and Technology, Banyeon, Ulsan 689-798, South Korea
    • Interdisciplinary School of Green Energy/Institute of Advanced Materials and Devices, Ulsan National Institute of Science and Technology, Banyeon, Ulsan 689-798, South Korea
    Search for more papers by this author
  • Liming Dai,

    Corresponding author
    1. Interdisciplinary School of Green Energy/Institute of Advanced Materials and Devices, Ulsan National Institute of Science and Technology, Banyeon, Ulsan 689-798, South Korea
    2. Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106
    • Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106
    Search for more papers by this author
  • Jong-Beom Baek

    Corresponding author
    1. Interdisciplinary School of Green Energy/Institute of Advanced Materials and Devices, Ulsan National Institute of Science and Technology, Banyeon, Ulsan 689-798, South Korea
    • Interdisciplinary School of Green Energy/Institute of Advanced Materials and Devices, Ulsan National Institute of Science and Technology, Banyeon, Ulsan 689-798, South Korea
    Search for more papers by this author

Abstract

Two model polymers, containing fluorene as an electron-donating moiety and benzothiadiazole (BT) as an electron-accepting moiety, have been synthesized by Suzuki coupling reaction. Both polymers are composed of the same chemical composition, but the BT acceptor can be either at a side-chain (i.e., S-polymer) or along the polymer main chain (i.e., M-polymer). Their optical, electrochemical, and photovoltaic properties, together with the field-effect transistor (FET) characteristics, have been investigated experimentally and theoretically. The FET carrier mobilities were estimated to be 5.20 × 10−5 and 3.12 × 10−4 cm2 V−1 s−1 for the S-polymer and M-polymer, respectively. Furthermore, polymeric solar cells (PSCs) with the ITO/PEDOT:PSS/S-polymer or M-polymer:PC71BM(1:4)/Al structure were constructed and demonstrated to show a power conversion efficiency of 0.82 and 1.24% for the S-polymer and M-polymer, respectively. The observed superior device performances for the M-polymer in both FET and PSCs are attributable to its relatively low band-gap and close molecular packing for efficient solar light harvesting and charge transport. This study provides important insights into the design of ideal structure–property relationships for conjugate polymers in FETs and PSCs. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Ancillary