Centers & Labs

RIKEN Center for Emergent Matter Science

Emergent Functional Polymers Research Team

Team Leader: Keisuke Tajima (Ph.D.)
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 Field


Related Research Fields

Engineering / Materials Sciences

Research Subjects

  • Development of new semiconducting polymers with low bandgaps
  • Nanostructure control in thin films by self-organization of semiconducting polymers
  • Search for the ideal molecular interfaces in organic solar cells

Selected Publications

  1. Wang, F., Hashimoto, K. and Tajima, K.:
    “Optical Anisotropy and Strong H-Aggregation of Poly(3-Alkylthiophene) in a Surface Monolayer”
    Adv. Mater. 27, 6014-6020 (2015).
  2. Izawa, S., Nakano, K., Suzuki, K., Hashimoto, K. and Tajima, K.:
    “Dominant Effects of First Monolayer Energetics at Donor/Acceptor Interfaces on Organic Photovoltaics”
    Adv. Mater. 27, 3025-3031 (2015).
  3. Zhong, Y. F., Izawa, S., Hashimoto, K., Tajima, K., Koganezawa, T. and Yoshida H.:
    “Crystallization-Induced Energy Level Change of [6,6]-Phenyl-C61-Butyric Acid Methyl Ester (PCBM) Film: Impact of Electronic Polarization Energy”
    J. Phys. Chem. C 119, 23-28 (2015).
  4. Zhou, E.J., Nakano, M., Izawa, S., Cong, J.Z., Osaka, I., Takimiya, K. and Tajima, K.:
    “All-Polymer Solar Cell with High Near-infrared Response Based on A Naphthodithiophene Diimide (NDTI) Copolymer”
    ACS Macro Lett. 3, 872-875 (2014).
  5. Izawa, S., Hashimoto, K. and Tajima, K.:
    “Surface Functionalization of Organic Semiconductor Films by Segregated Monolayers”
    Phys. Chem. Chem. Phys. 16, 16383-16387 (2014).
  6. Ma, J.S., Hashimoto, K., Koganezawa, T. and Tajima, K.:
    “Enhanced Vertical Carrier Mobility in Poly(3-alkylthiophene) Thin Films Sandwiched with Self-assembled Monolayer and Surface-segregated Layer”
    Chem. Commun. 50, 3627-3630 (2014).
  7. Zhong, Y.F., Tada, A., Izawa, S., Hashimoto, K. and Tajima, K.:
    “Enhancement of VOC without Loss of JSC in Organic Solar Cells by Modification of Donor/Acceptor Interfaces”
    Adv. Energy Mater. 4, 1301332 (2013).
  8. Zhou, E.J., Cong, J.Z., Hashimoto, K. and Tajima, K.:
    “Control of Miscibility and Aggregation via Material Design and Coating Process for High-Performance Polymer Blend Solar Cell”
    Adv. Mater. 25, 6991–6996 (2013).
  9. Ma, J.S., Hashimoto, K., Koganezawa, T. and Tajima, K.:
    “End-On Orientation of Semiconducting Polymers in Thin Films Induced by Surface Segregation of Fluoroalkyl Chains”
    J. Am. Chem. Soc. 135, 9644-9647 (2013).
  10. Zhong, Y.F., Ma, J.S., Hashimoto, K. and Tajima, K.:
    “Electric Field-Induced Dipole Switching at the Donor/Acceptor Interface in Organic Solar Cells”
    Adv. Mater. 25, 1071-1075 (2013).

Lab Members

Principal Investigator

Keisuke Tajima
Team Leader

Core Members

Kyohei Nakano
Postdoctoral Researcher
Jianming Huang
Postdoctoral Researcher
Soo Won Heo
Postdoctoral Researcher
Chao Wang
Postdoctoral Researcher
Kouki Akaike
Visiting Scientist
Tomohiro Mayumi
Student Trainee
Kaori Suzuki
Technical Staff II
Yujiao Chen
Technical Staff II

Contact information

N301-1, Chemistry and Materials Physics Building, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan

Email: keisuke.tajima [at]

Related links

Recent research results

November 6, 2015: RIKEN RESEARCH
Light-absorbing polymers stand to attention