Abrupt Morphology Change upon Thermal Annealing in Poly(3-Hexylthiophene)/Soluble Fullerene Blend Films for Polymer Solar Cells

Authors

  • Minjung Shin,

    1. Organic Nanoelectronics Laboratory Department of Chemical Engineering Kyungpook National University Daegu 702-701 (Republic of Korea)
    Search for more papers by this author
  • Hwajeong Kim,

    1. Organic Nanoelectronics Laboratory Department of Chemical Engineering Kyungpook National University Daegu 702-701 (Republic of Korea)
    2. Former address: Institute of Biomedical Engineering, Imperial College London, London SW7 2AZ (UK)
    Search for more papers by this author
  • Jiho Park,

    1. Organic Nanoelectronics Laboratory Department of Chemical Engineering Kyungpook National University Daegu 702-701 (Republic of Korea)
    Search for more papers by this author
  • Sungho Nam,

    1. Organic Nanoelectronics Laboratory Department of Chemical Engineering Kyungpook National University Daegu 702-701 (Republic of Korea)
    Search for more papers by this author
  • Kyuyoung Heo,

    1. Department of Chemistry National Research Laboratory for Polymer Synthesis and Physics Center for Electro-Photo Behaviors in Advanced Molecular Systems Division of Advanced Materials Science, Polymer Research Institute BK School of Molecular Science Pohang University of Science & Technology Pohang 790-784 (Republic of Korea)
    Search for more papers by this author
  • Moonhor Ree,

    1. Department of Chemistry National Research Laboratory for Polymer Synthesis and Physics Center for Electro-Photo Behaviors in Advanced Molecular Systems Division of Advanced Materials Science, Polymer Research Institute BK School of Molecular Science Pohang University of Science & Technology Pohang 790-784 (Republic of Korea)
    Search for more papers by this author
  • Chang-Sik Ha,

    1. Department of Polymer Science and Engineering Pusan National University Busan 609-735 (Republic of Korea)
    Search for more papers by this author
  • Youngkyoo Kim

    Corresponding author
    1. Organic Nanoelectronics Laboratory Department of Chemical Engineering Kyungpook National University Daegu 702-701 (Republic of Korea)
    2. Former address: Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2AZ (UK)
    • Organic Nanoelectronics Laboratory Department of Chemical Engineering Kyungpook National University Daegu 702-701 (Republic of Korea).
    Search for more papers by this author

Abstract

The in situ morphology change upon thermal annealing in bulk heterojunction blend films of regioregular poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 (PCBM) is measured by a grazing incidence X-ray diffraction (GIXD) method using a synchrotron radiation source. The results show that the film morphology—including the size and population of P3HT crystallites—abruptly changes at 140 °C between 5 and 30 min and is then stable up to 120 min. This trend is almost in good agreement with the performance change of polymer solar cells fabricated under the same conditions. The certain morphology change after 5 min annealing at 140 °C is assigned to the on-going thermal transition of P3HT molecules in the presence of PCBM transition. Field-emission scanning electron microscopy measurements show that the crack-like surface of blend films becomes smaller after a very short annealing time, but does not change further with increasing annealing time. These findings indicate that the stability of P3HT:PCBM solar cells cannot be secured by short-time annealing owing to the unsettled morphology, even though the resulting efficiency is high.

Ancillary