Prof.
Kyoto University/ Department of Molecular Engineering/ Nishikyo-ku, Kyoto 615-8510, JAPAN
Organic conjugated molecular materials have been the center of materials chemistry on electronic functional materials since the end of last century. Even without referring to the functionals of graphene-based system, spatial arrangement of electronic conjugated molecules confined into 2D-3D structures have been the key to tune electronic density of states, effective mass of electrons, electron mobility and conductivity. The structures are, however, realized and stabilized by “weak” and/or “medium” inter-molecular force fields which has been discussed sophisticatedly by thermodynamics and statistical mechanics. The assessment technique of charge carrier mobility in condensed phases of molecular materials allow us to overlook simple and clear interplays between the structural fluctuation of the molecular condensates and electronic properties, as well some exceptional structures giving unique electronic property in terms of classical thermodynamics/statistical mechanics on “fluctuation”. We show such quantitative interplays, pointing out the exceptional structures in terms of molecular asymmetry/chirality. The future design of conjugated molecular condensates for electronics and spintronics is also discussed according to our hypothesis to violate Wallach’s rule: how to realise asymmetric molecular condensates with high enough electronic density of states, a requisite for efficient translational motion of charges and pins.
CURRICULUM VITAE (CV)
| Name | Shu SEKI |
| Date of Birth | October 23rd, 1968 |
| Research Institution, Academic Unit (School, Faculty, etc.) & Position | Department of Molecular Engineering, Kyoto University Professor |
| Academic Degree | Dr. of Engineering, Osaka University (2002) |
Research Achievements of the PI: Prof. Shu SEKI
Prof. Shu Seki has worked on the electronic, optical, and spintronic materials chemistry and physics of conjugated molecular materials. The candidate PI has tried to measure, quantitate, and analyse physical properties of molecular substances in terms of charge carrier mobility, electronic conductivity, intermediates, electron spin momentum, etc. with unique spectroscopic techniques of time-resolved microwave conductivity, dielectric-loss spectroscopy, and transient optical spectroscopy techniques. The targets of molecular materials with electronic conjugated systems have been also of his interest developing a variety of low-dimensional organic conjugated molecules including conjugated macromolecular systems, covalent organic frameworks, and supramolecular architectures.
In the early carrier of his research, he worked on the radiation chemistry of organic systems: polysilanes as s-conjugated polymers. Charged spices of the conjugated backbones were produced quantitatively with radiation chemical processes, enabling to elucidate electronic coupling of the charges with vibronic state of the backbones via transient spectroscopy. The polaronic interaction leads precise design of conjugated backbones with confined helical structures, which demonstrated the helical pitches as well as persistence length of the backbone are the prime factors for the band-like transport of electrons (S. Seki, et al., J. Am. Chem. Soc. 2004, 126, 3521; Adv. Mater. 2002, 14, 228).
A variety of polymeric materials have been also applied a powerful platform for organic nanomaterials fabrication in his research. Electronic functional 1-dimensional nanostructures have been seamlessly fabricated and demonstrated as materials exhibiting wide range of functionality of optical, electronic, mechanical, enzymatic, and sensing applications (Adv. Mater. 2001, 13, 1663; Nature Commun., 2014, 5, 1; 2019, 10, 102; 2021, 12, 1, etc.).
Throughout the above research activities, his works have been sorely on the fundamental understanding as well as device application of electronic properties of conjugated molecular materials. Transient spectroscopies of the materials provide deep insights on the electronic structure of the molecules simulating charges transporting in the media, and he has been developed not only transient optical spectroscopies but also microwave-based electronic conductivity assessment techniques: Time-Resolved Microwave Conductivity (TRMC) measurements. According to the non-invasive(non-contact) nature of TRMC measurements, the technique has been applied for the assessment of electronic conductivity/mobility of charge carriers for an extremely wide range of molecular materials, elucidating the inherent nature of the molecules (S. Seki, et al., Nature Chem. 2016, 9, 493; 2014, 6, 690; Nature Commun. 2013, 4, 1691; 2013, 4, 1969; 2013, 4, 2694; 2015, 6, 8215; 2019, 10, 4217; 2020, 11, 1149; 2023, 14, 2741; J. Am. Chem. Soc. 2008, 130, 8886; 2008, 130, 13812; 2008, 130, 14772; 2009, 131, 408; 2009, 131, 7287; 2009, 131, 17722; 2009, 131, 18046; 2009, 131, 18030; 2010, 132, 6628; 2010, 132, 8866; 2010, 132, 14754; 2011, 133, 2766; 2011, 133, 6537; 2011, 133, 8896; 2011, 133, 10736; 2011, 133, 17746; 2011, 133, 18614; 2012, 134, 2524; 2012, 134, 7983; 2012, 134, 11681; 2012, 134, 19035; 2013, 135, 870; 2013, 135, 1284; 2013, 135, 8185; 2013, 135, 14797; 2013, 135, 18268; 2014, 136, 1742; 2014, 136, 13818; 2014, 136, 14589; 2015, 137, 893; 2015, 137, 5231; 2016, 138, 11727; 2017, 139, 18616; 2018, 140, 7152; 2020, 142, 12596; 2021, 143, 1046; 2024, 146, 8557; 2024, 146, 17084; 2024, 146, 17428; 2024, 146, 22642; Science 2006, 314, 1761; 2011, 334, 340.)
Condensed phases of conjugated molecular materials have, however, a lower gravitational density which is also a prime factor for tuning the electronic density of states and hence the effective mass of electrons governing the translational motion of charges/spins in the systems. In particular asymmetric systems with chirality are disadvantageous for the tuning because of the well-established Wallach’s rule in the gravitational density of molecular condensates. According to his findings on the low dimensional asymmetric systems violating the rule: anti-Wallach rule (S. Seki, et al.,Acc. Chem Res. 2024, 57, 2665), he has been working on the optoelectronic and spintronic properties of conjugated molecular systems. The key molecular platforms are 2D conjugated polymeric materials including covalent organic frameworks (S. Seki, et al., Nature Mater. 2018, 17, 625; 2023, 22, 807; Nature Synthesis 2023, 2, 848; Nature Commun. 2016, 4, 2736; 2015, 6, 7786; 2018, 99, 1660; 2022, 13, 6317; J. Am. Chem. Soc. 2010, 132, 6742; 2011, 133, 14510; 2012, 134, 12932; 2012, 134, 8360; 2020, 142, 9752; 2024, 146, 23497).
PI’s experience as a representative of a large international collaboration
Prof. Shu SEKI has played a key role as a representative of several large international collaboration programs.
- MEXT Grant-in-Aid for Transformative Research Areas “Condensed Conjugation” 2020-2025 (https://x-con.jp/en) Role: The Leader. This research program provided by MEXT, Japan has been conducted to invent the new concept of electronic conjugation with more than 40 PIs in Japan with 6 overseas advisors. The program will be accomplished in March 2025, providing the stiff base of this research project “Asymmetric Electronic Conjugation”. Throughout the project, we have published more than 100 papers via international collaborative research works.
- EU Horizon 2020 project “UHMob” (https://www.uhmob.eu/) Role: Partner PI. This is the international collaborative research project for the design of functional molecular systems exhibiting ultra-high charge carrier mobility competitive to Si/Oxide semiconductor materials. The project has been designed to pursue the aim with ~15 Ph.D candidates and pos-docs from 2018-2023, funded by EU governments. Prof. Shu SEKI co-supervised 5 Ph.D. candidates in the project from University of Cambridge, Free University of Brussels, Max-Planck Institute, Universite de Strasbourg, Universite de Mons, and TU Graz.
More than the above projects, Prof. Shu SEKI has been served for 5 JSPS bilateral international collaborative researches, as well as visiting professor positions in 4 overseas universities.
Research Career and Experience
Educational Background
2002 Dr. of Engineering, Osaka University
Thesis Title: Electronic Properties and Reaction Mechanisms of Polysilanes”
1993 Master of Engineering, The University of Tokyo
1991 Bachelor of Engineering, The University of Tokyo
Professional Career
2024 Visiting Professor of Fudan University, China
2021 Fellow of the University of Strasbourg, France
2019 Visiting Professor of Tianjin University, China
2019 Visiting Professor of Amity University, India
2015 Visiting Professor of Massachusetts Institute of Technology
2015 Professor of Chemistry, Department of Molecular Engineering, Kyoto University
2008 Professor of Chemistry, Department of Applied Chemistry Osaka University
2001 Associate Professor, Institute of Scientific and Industrial Research, Osaka University
2000 Research Associate, Delft University of Technology
1995 Assistant Professor, Institute of Scientific and Industrial Research, Osaka University
Scientific Activities
Organizing Committee and Chair of Physical Chemistry, PACIFICHEM2025; Organizing Committee and Program Chair, PACIFICHEM2020(2021); Associate Editor of “Material Chemistry Frontier”, Royal Society of Chemistry; Associate Editor of Scientific Reports”, Nature Publishing Group; Editorial Board member of >5 International Journals published by American Physical Society, Royal Society of Chemistry, Wiley, Cell Press, and Elsevier.
Award and Honors
2020 USIAS Fellow of University of Strassburg
2015 Fellow of the Royal Society of Chemistry
Research Summary
The PI: Prof. Shu Seki has pursued fundamental understanding of intrinsic electronic, optical, and spintronic properties of conjugated molecular materials. The interplay of the physical properties and steady state (static) structure of conjugated molecular materials has been always the center of the research works, and rapid and efficient screening techniques of the property measures have been realized by a series of unique spectroscopy techniques developed by the PI. Electronic conductivity of the molecular materials with the measure of m: mobility of charge carriers is the major theme since the last decade, and the quantitative estimates of m by Time-Resolved Microwave Conductivity (TRMC) measurements have been collected for more than 1000 molecules. According to the statistical analysis of the measures over the molecules and their structures in the condensed phases, we have approached the ground-breaking concepts of “Anti-Wallach” rule which has been verified over 100 years: this is the case giving the idea of the present international joint research project. Starting from static structure of molecular condensates represented by well ordered crystalline structures, the statistical analysis inspires us on the key role of the dynamic structural perturbation in the optimization of electronic/spintronic properties of molecular materials. Now we are tackling on the interplay of structural dynamics/asymmetry and electronic/spintronic/magnetoptical properties in the molecular materials.
Citation Metrics
Original Papers Published: >650 papers at Feb.1st, 2025.
Number of Citations: 29000 at Feb. 1st, 2025.
h-index: 84 at Feb. 1st, 2025.
Representative Scientific Publication
- “Rolling Two-Dimensional Covalent Organic Framework (COF) Sheets into One-Dimensional Electronic and Proton Conductive Nanotubes”, Z. Li, R. P. Paitandi, Y. Tsutsui, W. Matsuda, M. Nobuoka, B. Chen, S. Ghosh, T. Tanaka, M. Suda, T. Zhu, H. Kageyama, Y. Miyake, H. Shinokubo, S. Seki
- “Electron Transport over 2D Molecular Materials and Assemblies” S. Seki, R. P. Paitandi, W. Choi, S. Ghosh, T. Tanaka, Acc. Chem. Res. 2024, 57, 2665-2677.
- “Electrons lighter than ever”, S. Seki, Z. Li, Nature Materials 2023, 22, 807-808.
- “Ubiquitous organic molecule-based free-standing nanowires with ultra-high aspect ratios”, K. Kamiya, K. Kayama, M. Nobuoka, S. Sakaguchi, T. Sakurai, M. Kawata, Y. Tsutsui, M. Suda, A. Idesaki, H. Koshikawa, M. Sugimoto, G.B.V.S. Lakshmi, D.K. Avasthi, S. Seki, Nature Communications, 2021, 12, 4025.
- “Excited-state intramolecular proton-transfer (ESIPT)-inspired solid state emitters”, V. S. Padalkar, S Seki, Chem. Soc. Rev. 2016, 45, 169-202.
- “Identification of prime factors to maximize the photocatalytic hydrogen evolution of covalent organic frameworks”, S. Ghosh, A. Nakada, M. A Springer, T. Kawaguchi, K. Suzuki, H. Kaji, I. Baburin, A. Kuc, T. Heine, H. Suzuki, R. Abe, S. Seki, J. Am Chem Soc. 2020, 142, 9752-9762.
