Faculty
Akihiko Fujiwara
Major research activity
Materials Science, Energy-Related Materials, Synchrotron Radiation Analysis
High-performance energy-related materials are vital for reduction of energy consumption. We aim to develop new materials for this purpose. Current research topics are development of materials for high-capacity lithium ion batteries and low-power electronics. The former is development of organosulfur polymers for cathode materials of lithium ion batteries. The advantages of these polymers are light weight and wide range of valence of sulfur for high capacity. High electric conductivity and high stability are expected by designing appropriate polymer structures. Mechanism of the redox reaction is now investigated for further improvement. The latter is development of an amorphous oxide semiconductor of silicon doped In2O3(In-Si-O) system. Doping of silicon is essential for stabilization of amorphous structure, directly connected to robustness as a device material. Detailed mechanism of high performance and high stability is now under investigation. Our distinctive approach is utilization of cutting-edge synchrotron radiation analysis, such as nano-beam diffraction and spectroscopy, which provide guideline for the designing novel materials.
Major relevant publications
- N. Mitoma, S. Aikawa, W. Ou-Yang, X. Gao, T. Kizu, M. F. Lin, A. Fujiwara, T. Nabatame and K. Tsukagoshi: “Dopant selection for control of charge carrier density and mobility in amorphous indium oxide thin-film transistors: Comparison between Si- and W-dopants”, Appl. Phys. Lett. 106(2015) 042106.
- S. Kohara, J. Akola, L. Patrikeev, M. Ropo, K. Ohara, M. Itou, A. Fujiwara, J. Yahiro, J. T. Okada, T. Ishikawa, A. Mizuno, A. Masuno, Y. Watanabe, T. Usuki: “Atomic and electronic structure of an extremely fragile liquid”, Nat. Commun. 5(2014) 5892.
- K. Sugimoto, H. Uemachi, M. Maekawa and A. Fujiwara: “Air-Stable Cyclohexasulfur as Cocrystal”, Cryst. Growth Des. 13(2013) 433 – 436.
- T. Takano, H. Masunaga, A. Fujiwara, H. Okuzaki,T. Sasaki: “PEDOT Nanocrystal in Highly Conductive PEDOT:PSS Polymer Films”, Macromolecules 45(2012) 3859 - 3865.
- A. Fujiwara, K. Sugimoto, C. H. Shih, H. Tanaka, J. Tang, Y. Tanabe, J. Xu, S. Heguri, K. Tanigaki, M. Takata: “Quantitative relation between structure and thermal conductivity in type-I clathrates X8Ga16Ge30 (X = Sr, Ba) based on electrostatic-potential analysis”, Phys. Rev. B 85(2012) 144305.