Chapter 4
Nanoscale First-Principles Electronic
Structure Simulations of Materials
Relevant to Organic Electronics
Susumu Yanagisawa and Ikutaro Hamada
Abstract Organic molecular materials have attracted considerable attention as a
candidate for next-generation flexible electronics in the near future. However, there
still remain open questions on fundamental electronic properties such as mechanisms of the carrier transport and barriers for carrier injection at organic-inorganic
heterojunctions. In this review, we illustrate the progresses in first-principles
electronic structure calculations of the materials for investigation of the atomicor molecular-scale electronic properties of organic semiconductor materials, which
are in general difficult to observe even with present-day experimental techniques.
The theoretical studies not only help elucidate the mechanism of the experimental
measurement but also may allow us to gain insights into the essences of the
materials properties in terms of the electronic structure. Specifically, in this article,
we focus on the first-principles theoretical treatment of the geometric configurations
of organic semiconductors and their electronic structure at the level beyond the
approximation to the density functional theory (DFT) such as the local density
(LDA) and generalized gradient approximations (GGA), i.e., the van der Waalsinclusive methods for describing the weak intermolecular interaction in organic
solids and the many-body perturbation theory within the GW approximation for
treatment of the charged excitation (quasiparticle) and thus the fundamental gap
and the band dispersion of the crystals. Here, we illustrate the recent studies on
(i) the effect of the molecular configuration on the quasiparticle energy in organic
semiconductors, (ii) the energy level alignment at organic-metal interfaces, and
(iii) prediction of the charge injection levels at a surface of organic thin film, i.e.,
the ionization energy and the electron affinity. Further progresses in theoretical
S. Yanagisawa ()
Faculty of Science, Department of Physics and Earth Sciences, University of the Ryukyus,
Nishihara, Okinawa, Japan
e-mail: shou@sci.u-ryukyu.ac.jp
I. Hamada
Department of Precision Science and Technology, Graduate School of Engineering,
Osaka University, Suita, Osaka, Japan
e-mail: ihamada@prec.eng.osaka-u.ac.jp
© Springer Nature Singapore Pte Ltd. 2020
T. Onishi (ed.), Theoretical Chemistry for Advanced Nanomaterials,
https://doi.org/10.1007/978-981-15-0006-0_4
89
Nanoscale First-Principles Electronic
Structure Simulations of Materials
Relevant to Organic Electronics
Susumu Yanagisawa and Ikutaro Hamada
Abstract Organic molecular materials have attracted considerable attention as a
candidate for next-generation flexible electronics in the near future. However, there
still remain open questions on fundamental electronic properties such as mechanisms of the carrier transport and barriers for carrier injection at organic-inorganic
heterojunctions. In this review, we illustrate the progresses in first-principles
electronic structure calculations of the materials for investigation of the atomicor molecular-scale electronic properties of organic semiconductor materials, which
are in general difficult to observe even with present-day experimental techniques.
The theoretical studies not only help elucidate the mechanism of the experimental
measurement but also may allow us to gain insights into the essences of the
materials properties in terms of the electronic structure. Specifically, in this article,
we focus on the first-principles theoretical treatment of the geometric configurations
of organic semiconductors and their electronic structure at the level beyond the
approximation to the density functional theory (DFT) such as the local density
(LDA) and generalized gradient approximations (GGA), i.e., the van der Waalsinclusive methods for describing the weak intermolecular interaction in organic
solids and the many-body perturbation theory within the GW approximation for
treatment of the charged excitation (quasiparticle) and thus the fundamental gap
and the band dispersion of the crystals. Here, we illustrate the recent studies on
(i) the effect of the molecular configuration on the quasiparticle energy in organic
semiconductors, (ii) the energy level alignment at organic-metal interfaces, and
(iii) prediction of the charge injection levels at a surface of organic thin film, i.e.,
the ionization energy and the electron affinity. Further progresses in theoretical
S. Yanagisawa ()
Faculty of Science, Department of Physics and Earth Sciences, University of the Ryukyus,
Nishihara, Okinawa, Japan
e-mail: shou@sci.u-ryukyu.ac.jp
I. Hamada
Department of Precision Science and Technology, Graduate School of Engineering,
Osaka University, Suita, Osaka, Japan
e-mail: ihamada@prec.eng.osaka-u.ac.jp
© Springer Nature Singapore Pte Ltd. 2020
T. Onishi (ed.), Theoretical Chemistry for Advanced Nanomaterials,
https://doi.org/10.1007/978-981-15-0006-0_4
89