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RIKEN Center for Emergent Matter Science Emergent Functional Polymers Research Team

Team Leader: Keisuke Tajima (Ph.D.)

Research Summary

Keisuke  Tajima(Ph.D.)

We work on the development of new organic semiconducting polymer materials and their application to organic electronic devices. Specifically, we seek the methodology and the molecular design to control the precise structures in molecular- and nano-scale at our will, and try to find breakthroughs to drastically enhance the performance of the organic electronic devices. Targets of our research are not only the conventional organic solar cells and field-effect transistors, but also the organic electronic devices with new functions based on the structure controls.

Main Research Fields

  • Chemistry

Related Research Fields

  • Engineering


  • Organic solar cells
  • Semiconducting organic polymers
  • Thin films
  • Nanostructures
  • Interfacial science

Selected Publications

  • 1. Wang, W.-C., Chen, S.-Y., Yang, Y.-W., Hsu, C. S., and Tajima, K.:
    "Face-on Reorientation of π-Conjugated Polymers in Thin Films by Surface-Segregated Monolayers"
    J. Mater. Chem. A 4, 2070013 (2020).
  • 2. Nakano, K., Chen, Y., and Tajima, K.:
    "Quantifying Charge Carrier Density in Organic Solar Cells by Differential Charging Techniques"
    AIP Adv. 9, 125205 (2019).
  • 3. Tajima, K.:
    "Look Beyond the Surface: Recent Progress in Applications of Surface-segregated Monolayers for Organic Electronics"
    Polym. J. 51, 1117 (2019).
  • 4. Nakano, K., Chen, Y., Xiao, B., Han, W., Huang, J., Yoshida, H., Zhou, E. J., and Tajima, K.:
    "Anatomy of the Energetic Driving Force for Charge Generation in Organic Solar Cells"
    Nat. Comm. 10, 2520 (2019).
  • 5. Wang, F., Nakano, K., Segawa, H., and Tajima, K.:
    "Phytol-derived Alkyl Side-chains for ¬π-Conjugated Semiconducting Polymers"
    Chem. Mater. 31, 2097 (2019).
  • 6. Wang, F., Nakano, K., Yoshida, H., Hashimoto, K., Segawa, H., Hsu, C.-S., and Tajima, K.:
    "Effects of End-On Oriented Polymer Chains at the Donor/Acceptor Interface in Organic Solar Cells"
    J. Mater. Chem. A 6, 22880 (2018)
  • 7. Wang, F., Hashimoto, K., Segawa, H., and Tajima, K.:
    "Synthesis of Poly(3-butylthiophene) with Trisiloxane End Group and Its Surface Segregation Behavior inThin Films"
    J. Photopolym. Sci. Tech. 31, 151 (2018)
  • 8. Wang, C., Nakano, K., Lee, H. F., Chen, Y., Hong, Y.-L., Nishiyama, Y., and Tajima, K.:
    "Intermolecular Arrangement of Fullerene Acceptors around Semiconducting Polymers in Mixed Bulk Heterojunctions"
    Angew. Chem. Int. Ed 57, 7034 (2018)
  • 9. Wang, F., Hashimoto, K., Segawa, H., and Tajima, K.:
    "Effects of Chain Orientation in Self-Organized Buffer Layers Based on Poly(3-alkylthiophene)s for Organic Photovoltaics"
    ACS Appl. Mater. Interfaces 10, 8901 (2018)
  • 10. Ohnishi, I., Hashimoto, K., and Tajima K.:
    "Synthesis of Diketopyrrolopyrrole-based Polymers with Polydimethylsiloxane Side Chains And Their Application in Organic Field-effect Transistors"
    R. Soc. open sci. 5, 172025 (2018)

Recent Research Results

Related Links

Lab Members

Principal investigator

Keisuke Tajima
Team Leader

Core members

Kyohei Nakano
Research Scientist
Chao Wang
Special Postdoctoral Researcher
Hitoshi Saito
Special Postdoctoral Researcher
Yuto Ochiai
Postdoctoral Researcher
Takaho Yokoyama
Postdoctoral Researcher
Yumiko Kaji
Technical Staff II
Masamichi Fujihira
Senior Visiting Scientist
Akira Ohno
Visiting Scientist
Wei-Chih Wang
International Program Associate

Contact Information

N301-1, Chemistry and Materials Physics Building,
2-1 Hirosawa, Wako,
Saitama 351-0198, Japan
Email: keisuke.tajima [at] riken.jp