''First-principles investigation on the electronic states of the organic single-crystals and the organic-metal interfaces: importance of accurate prediction of the crystal and the interface structures'' Prof. Susumu Yanagisawa

Speaker:

Prof. Susumu Yanagisawa
Department of Physics and Earth Sciences, Faculty of Science,
University of the Ryukyus

Title:

First-principles investigation on the electronic states of the organic single-crystals and the organic-metal interfaces: importance of accurate prediction of the crystal and the interface structures

Abstract:

These years, there has been enormous attention paid to development of organic semiconductor materials for next-generation flexible electronics.
To enhance the performances and the functions of the materials, more understanding on the materials properties at the nano-scale size is required.
There have been more and more efforts made to understand the electronic properties of the organic materials both experimentally and theoretically.

In this talk, I will present my recent theoretical works on the electronic properties of the organic solids.
I focus on the two topics:
i)  Interface dipole dominating the energy level alignment at the organic-metal interface: pentacene-metal and Alq3-metal interfaces as examples
ii) Band structure and its dispersion of organic single crystals and its origin: cases of rubrene and metal-phthalocyanine

The former topic is related to the formation of the charge injection barrier right at the organic-electrode interface, and the latter one is to the recently proposed band-like carrier transport in organic semiconductor single crystals.
For theoretical calculations, I employ the density functional theory (DFT) to predict the structural and electronic properties of the materials. I also use recently proposed variants of DFT to take into account the van der Waals (vdW) interaction dominating the intermolecular and the molecule-substrate interactions.

The importance of the accurately predicted crystal and interface structures will be highlighted, and I will discuss the effects of the structures on the electronic properties.

References
[1] S. Yanagisawa, K. Lee and Y. Morikawa, J. Chem. Phys. 128, 244704 (_2008_).
[2] K. Toyoda, I. Hamada, K. Lee, S. Yanagisawa, and Y. Morikawa, J. Chem. Phys. 132, 134703 (2010).
[3] S. Yanagisawa, Y. Morikawa, and A. Schindlmayr, Phys. Rev. B 88, 115438 (2013).
[4] S. Yanagisawa, K. Yamauchi, T. Inaoka, T. Oguchi, and I. Hamada, Phys. Rev. B 90, 245141 (2014).

Biography:

Education record
PhD, Department of Applied Chemistry, School of Engineering, University of Tokyo, Japan, 2004; Supervisor: Professor Dr. Kimihiko Hirao

Work Experience
October 2003-March 2004
Postdoctoral fellow, Intelligent Modeling Laboratory, University of Tokyo
April 2004-September 2009
Postdoctoral fellow, Institute of Scientific and Industrial Research, Osaka University
October 2009-March 2011
Postdoctoral fellow, Department of Precision Science and Technology, Osaka University
April 2011-March 2014
Assistant Professor, Department of Physics and Earth Sciences, Faculty of Science University of the Ryukyus
April 2014-Present
Associate Professor, Department of Physics and Earth Sciences,

Host:
Prof. Yabing Qi