Hiroyuki Ishii, Ph.D.

Recent Topics

The objective of my research is to analyze and to understand the electron transport properties of various materials for the applications to novel high-performance electron devices, such as transistors, solar cells and others. Therefore, I have developed a large-scale quantum transport simulation method, called as "Time-dependent Wave-packet diffusion (TD-WPD) method".

TD-WPD method is based on the full treatment of quantum theory and computes the quantum transport properties for various huge systems with up to 10^8 atoms, which enables me to treat electron transport problems from classical diffusion regime to quantum ballistic regime. In this methodology, I calulcate the time-evolution of electron wavepackets and evaluate the conductivity, the mobility and the mean free path within the Kubo formula.

• Development of Order-N transport calculation methodology based on quatum theory for electric transport, Hall effects, and thermoelectric effects.
  
• Transport of carrier couplied with inter- and intra-molecular vibrations of Organic single crystals
  
• Charge transport properties from ballistic to diffusive regime of Carbon nanotubes (Graphenes)
  

[Introduction of my research] (3pages article)

Other Topics

• Relaxation process of transient current throgh nano-contact systems
                                      using the Liouville equation of density matrix.
• Novel quatum transport and exciton properties of kagome quantum-wire system with flat-band.

• Doctor thesis
  "Quantum transport and Optical properties of Nanostructure network systems"
• Master thesis
  "Optical properties of the Kagome quantum-wire systems" (in Japanese)

Publications, Invited Talks, Oral presentations

• Publication list

Grants (Principal investigator)

• 2018-2021
  Grant-in-Aid for Scientific Research (B)
  Title: 第一原理に基づく熱電変換計算理論の開発と有機材料への応用 (18H01856)
  Principal investigator: Hiroyuki Ishii, Co-investigator: Toshihiro Okamoto
• 2015-2017
  Grant-in-Aid for Young Scientists (A)
  Title: Large-scale electron-transport theory for organic low and high molecular weight semiconductors (15H05418)
  Principal investigator: Hiroyuki Ishii
• 2012-2016
  JST-PRESTO, Research area "Molecular technology and creation of new functions"
  Title: Establishment of large-scale quantum transport simulation method for creation of high performance organic materials (JPMJPR12K2)
  Principal investigator: Hiroyuki Ishii
• 2012-2013
  Grant-in-Aid for Young Scientists (B)
  Title: Theoretical study on polaron transport mechanism of organic semiconductors using wave-packet dynamics (24760024)
  Principal investigator: Hiroyuki Ishii
• 2010-2011
  Grant-in-Aid for Research Activity start up
  Title: Development of large-scale quantum transport simulation method and Application to nano-carbon materials and organic thin films (22810003)
  Principal investigator: Hiroyuki Ishii

Grants (Co-investigator)

• 2017-2019
  Grant-in-Aid for Scientific Research (B)
  Title: 分子間振動の抑制を基軸とした次世代有機半導体材料の創製 (17H03104)
  Principal investigator: Toshihiro Okamoto, Co-investigator: Daisuke Hashizume, Hiroyuki Ishii
• 2011-2014
  Grant-in-Aid for Scientific Research (B)
  Title: Study of carrier mechanism of organic semiconductor by large scale transport calculation (23360018)
  Principal investigator: Nobuhiko Kobayashi, Co-investigator: Hiroyuki Ishii

Curriculum Vitae

[Education]

• B.S. in Physics, Chiba University, 1997.3 - 2001.3
• Ph.D. in Physics, Chiba University, 2001.4-2006.3
• Dissertation "Quantum transport and Optical properties of Nanostructure network systems"
  Advisor; Prof. T. Nakayama

[Employment]

• 2006.4 - 2007.3; Postdoctral Researcher,
  CREST-JST, Japan
• 2007.4 - 2009.3; Postdoctral Researcher,
  National Institute of Advanced Industrial Science and Technology (AIST), Japan
• 2009.4 - 2010.3; Postdoctral Researcher,
  School of Science, the University of Tokyo, Japan
• 2010.4.1 - 2013.6.15 ; Assistant Professor,
  Graduate School of Pure and Applied Sciences, University of Tsukuba, Japan
  (2012.8- ; NIMS Visiting Researcher)
  (2012.10.1 - 2013.6.15 ; JST-PRESTO Researcher)
  
• 2013.6.16 - 2016.3.31 ; JST-PRESTO Researcher
  (2013.6.16 - 2016.3.31 ; Visiting Associate Professor, Faculty of Pure and Applied Sciences, University of Tsukuba, Japan)
  
• 2016.4.1-2016.10.15 ; Senior Researcher, Faculty of Pure and Applied Sciences, University of Tsukuba, Japan
  
• 2016.10.16-2020.12.31 ; Assistant Professor, Faculty of Pure and Applied Sciences, University of Tsukuba, Japan)
  (Lecture:"Quantum mechanics A","Quantum theory for applied physics")
• 2021.1.1-2021.10.31 ; Senior Researcher, Pi-Material design Co., Japan
• 2021.6.1-2021.10.31 ; Project Researcher, Graduate School of Frontier Sciences, The University of Tokyo, Japan
• 2021.11.1- Associate Proffessor, Faculty of Pure and Applied Sciences, University of Tsukuba, Japan

Society Membership

• The Physical Society of Japan (JPS)
• The Japan Society of Applied Physics (JSAP)
• The Surface Science Society of Japan (SSSJ)
• American Physical Society (APS)
• The Chemical Society of Japan (CSJ)