Cross-sectional nanoscale morphology and interfacial band alignment of phase-separated polymer/fullerene by scanning tunneling microscopy and spectroscopy

ORAL

Abstract

The efficiency of organic films based on poly(3-hexylthiophene) (P3HT) and methanofullerene derivative (PCBM) was shown to be strongly dependent on the crystalline order inside. Through the suitable annealing process, the well-crystallized organic P3HT:PCBM films can be fabricated to enhance their charge transport. To further improve the efficiency of photo-induced charge separation and transport as well as the corresponding photocurrent, more detailed electronic information at both interfaces of the donors/accepters and photoactive-layer/electrode will be essential. In this work, cross-sectional scanning tunneling microscopy and spectroscopy were employed to investigate the interfacial properties of P3HT:PCBM films. The vertical phase distribution and local electronic structures across the interfaces of substrate/organic film and P3HT/PCBM are obtained at the atomic resolution. These electronic structures also provide direct observations of the interfacial band alignments, suggesting the possible carrier transport mechanism of P3HT:PCBM organic films.

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Authors

  • M.C. Shih

    • Department of Physics, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan

  • Y.P. Chiu

    • Department of Physics, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan

  • B.C. Huang

    • Department of Physics, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan

  • C.C. Lin

    • Department of Materials Science and Engineering, National Taiwan University, Taipei, 10617 Taiwan

  • S.S. Li

    • Department of Materials Science and Engineering, National Taiwan University, Taipei, 10617 Taiwan

  • C.S. Chang

    • Institute of Physics, Academia Sinica, Taipei 11529, Taiwan

  • C.W. Chen

    • Department of Materials Science and Engineering, National Taiwan University, Taipei, 10617 Taiwan