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RIKEN Center for Emergent Matter Science Emergent Molecular Function Research Group

Group Director: Kazuo Takimiya (D.Eng.)

Research Summary

Kazuo  Takimiya(D.Eng.)

The Research Group engages in the development and application of new functional organic molecules. Organic molecules can be designed and synthesized as they should have appropriate molecular and electronic structures for certain functionalities, and such functional molecules are utilized in fabricating optoelectronic devices such as organic field-effect transistors (OFETs) and organic solar cells (organic photovoltaics, OPVs). Recent our achievements are 1) development of high-performance molecular semiconductors applicable to OFETs with the highest mobilities, and 2) development of versatile semiconducting polymers that can be utilized to high performance solution-processed OTFTs and OPVs.

Main Research Fields

  • Chemistry

Related Research Fields

  • Engineering


  • Organic Semiconductors
  • Organic Field-Effect Transistors
  • Organic Solar Cells
  • Supramolecular Chemistry

Selected Publications

  • 1.Nakano, M., Osaka, I., Takimiya, K.:
    "Control of major carriers in ambipolar polymer semiconductor by self-assembled monolayers"
    Adv. Mater., 29, 1602893 (2017).
  • 2.Wang, Y., Nakano, M., Michinobu, T., Kiyota, Y., Mori, T., Takimiya, K.:
    "Naphthodithiophenediimide-Benzobisthiadiazole-Based Polymers: Versatile n-Type Materials for Field-Effect Transistors and Thermoelectric Devices"
    Macromolecules, 50, 857-864 (2017).
  • 3.Zafra, J. L., Qiu, L., Yanai, N., Mori, T., Nakano, M., Alvarez, M. P., Lopez Navarrete, J. T., Gomez-Garcia, C. J., Kertesz, M., Takimiya, K., Casado, J.:
    "Reversible Dimerization & Polymerization of a Janus Diradical Producing Labile CC Bonds and Giant Chromism"
    Angew. Chem. Int. Ed., 55, 14563-14568 (2016).
  • 4.Kawabata, K., Saito, M., Osaka, I., Takimiya, K.:
    "Very Small Bandgap π-Conjugated Polymers with Extended Thienoquinoids"
    J. Am. Chem. Soc., 138, 7725-7732 (2016).
  • 5.Nakano, M., Sawamoto, M., Yuki, M., Takimiya, K.:
    "N,N'-Unsubstituted Naphthodithiophene Diimide (NDTI): Synthesis and Derivatization via N-Alkylation and –Arylation"
    Org. Lett., 18, 3770-3773 (2016).
  • 6.Vohra, V., Kawashima, K., Kakara, T., Koganezawa, T., Osaka, I., Takimiya, K., Murata, H.:
    “Efficient inverted polymer solar cells employing favourable molecular orientation”
    Nat. Photon. 9, 403–408 (2015).
  • 7.Nakano, M., Osaka, I., Hashizume, D., Takimiya, K.:
    “α-Modified Naphthodithiophene Diimides-Molecular Design Strategy for Air-Stable n-Channel Organic Semiconductors”
    Chem. Mater. 27, 6418–6425 (2015).
  • 8.Takimiya, K., Osaka, I., Mori, T., and Nakano, M.:
    "Organic Semiconductors Based on [1]Benzothieno[3,2-b][1]benzothiophene Substructure"
    Acc. Chem. Res., 47, 1493–1502 (2014).
  • 9.Osaka, I., Kakara, T., Takemura, N., Koganezawa, T., and Takimiya, K.:
    "Naphthodithiophene–Naphthobisthiadiazole Copolymers for Solar Cells: Alkylation Drives the Polymer Backbone Flat and Promotes Efficiency"
    J. Am. Chem. Soc., 135, 8834–8837 (2013).
  • 10.Fukutomi, Y., Nakano, M., Hu, J.-Y., Osaka, I. and Takimiya, K.:
    "Naphthodithiophenediimide (NDTI): Synthesis, Structure, and Applications"
    J. Am .Chem. Soc., 135, 11445–11448 (2013)

Recent Research Results

Related Links

Lab Members

Principal investigator

Kazuo Takimiya
Group Director

Core members

Chengyuan Wang
Postdoctoral Researcher
Takuya Ogaki
Postdoctoral Researcher
Maitisidike Rukeyamu
Postdoctoral Researcher
Masahiro Nakano
Special Postdoctoral Researcher
Naoya Suzuki
Special Postdoctoral Researcher
Johan Jean-Claude Maurice Hamonnet
Technical Staff I
Kohsuke Kawabata
Visiting Scientist
Nobuhiko Ohtsuka
Junior Research Associate

Contact Information

504 Main Research Building,
2-1 Hirosawa,
Wako, Saitama
351-0198, Japan
Email: takimiya [at] riken.jp