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Your search keyword '"Takimiya, Kazuo"' showing total 1,269 results
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1,269 results on '"Takimiya, Kazuo"'

1. Tuning Spin Current Injection at Ferromagnet/Non-Magnet Interfaces by Molecular Design

Author

Wittmann, Angela, Schweicher, Guillaume, Broch, Katharina, Novak, Jiri, Lami, Vincent, Cornil, David, McNellis, Erik R., Zadvorna, Olia, Venkateshvaran, Deepak, Takimiya, Kazuo, Geerts, Yves H., Cornil, Jerome, Vaynzof, Yana, Sinova, Jairo, Watanabe, Shun, and Sirringhaus, Henning

Subjects
Physics - Applied Physics
Abstract

There is a growing interest in utilizing the distinctive material properties of organic semiconductors for spintronic applications. Here, we explore injection of pure spin current from Permalloy into a small molecule system based on dinaphtho[2,3-b:2,3-f]thieno[3,2-b]thiophene (DNTT) at ferromagnetic resonance. The unique tunability of organic materials by molecular design allows us to study the impact of interfacial properties on the spin injection efficiency systematically. We show that both, spin injection efficiency at the interface as well as the spin diffusion length can be tuned sensitively by the interfacial molecular structure and side chain substitution of the molecule.

Published
2020
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2. Chasing the killer phonon mode for the rational design of low disorder, high mobility molecular semiconductors

Author

Schweicher, Guillaume, D'Avino, Gabriele, Ruggiero, Michael T., Harkin, David J., Broch, Katharina, Venkateshvaran, Deepak, Liu, Guoming, Richard, Audrey, Ruzie, Christian, Armstrong, Jeff, Kennedy, Alan R., Shankland, Kenneth, Takimiya, Kazuo, Geerts, Yves H., Zeitler, J. Axel, Fratini, Simone, and Sirringhaus, Henning

Subjects
Condensed Matter - Materials Science
Abstract

Molecular vibrations play a critical role in the charge transport properties of weakly van der Waals bonded organic semiconductors. To understand which specific phonon modes contribute most strongly to the electron-phonon coupling and ensuing thermal energetic disorder in some of the most widely studied high mobility molecular semiconductors, state-of-the-art quantum mechanical simulations of the vibrational modes and the ensuing electron phonon coupling constants are combined with experimental measurements of the low-frequency vibrations using inelastic neutron scattering and terahertz time-domain spectroscopy. In this way, the long-axis sliding motion is identified as a killer phonon mode, which in some molecules contributes more than 80% to the total thermal disorder. Based on this insight, a way to rationalize mobility trends between different materials and derive important molecular design guidelines for new high mobility molecular semiconductors is suggested., Comment: 10 pages, 5 figures

Published
2019
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3. Tuning the effective spin-orbit coupling in molecular semiconductors

Author

Schott, Sam, McNellis, Erik R., Nielsen, Christian B., Chen, Hung-Yang, Watanabe, Shun, Tanaka, Hisaaki, McCulloch, Iain, Takimiya, Kazuo, Sinova, Jairo, and Sirringhaus, Henning

Subjects
Condensed Matter - Materials Science
Abstract

The control of spins and spin to charge conversion in organics requires understanding the molecular spin-orbit coupling (SOC), and a means to tune its strength. However, quantifying SOC strengths indirectly through spin relaxation effects has proven diffi- cult due to competing relaxation mechanisms. Here we present a systematic study of the g-tensor shift in molecular semiconductors and link it directly to the SOC strength in a series of high mobility molecular semiconductors with strong potential for future devices. The results demonstrate a rich variability of the molecular g-shifts with the effective SOC, depending on subtle aspects of molecular composition and structure. We correlate the above g -shifts to spin-lattice relaxation times over four orders of magnitude, from 200 {\mu}s to 0.15 {\mu}s, for isolated molecules in solution and relate our findings for isolated molecules in solution to the spin relaxation mechanisms that are likely to be relevant in solid state systems., Comment: Accepted for publication in Nature Communications

Published
2017
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27. Contrasted behaviours of methylthiolated perylene and pyrene as organic semiconductors: implications of molecular electronic structure and crystal structure.

Author

Takimiya, Kazuo, Bulgarevich, Kirill, and Horiuchi, Singo

Abstract

Following the ultrahigh mobility of 1,3,6,8-tetrakis(methylthio)pyrene (MT-pyrene)-based single-crystal transistors (SC-FETs), we have synthesized and characterized its closely related compound, 2,5,8,11-tetrakis(methythio)perylene (MT-perylene). Like parent pyrene and perylene with similar sandwich herringbone structures, MT-perylene crystallizes into a brickwork structure as MT-pyrene does. However, the transport properties of MT-perylene evaluated by SC-FETs were far inferior to those of MT-pyrene: about 0.2 cm2 V−1 s−1 for the former, whereas 32 cm2 V−1 s−1 for the latter. Such marked differences can be ascribed to the solid-state electronic structures, which are the outcome of both the molecular electronic structure and crystal structure in the solid state. This indicates the importance of choosing molecules that can realize an appropriate combination of molecular orbitals and solid-state structure so that the solid-state electronic structure is suitable for efficient carrier transport. [ABSTRACT FROM AUTHOR]

Published
2023
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45. Organic Semiconductors for Optoelectronics

Author

Naito, Hiroyoshi, Tanaka, Kazuyoshi, Singh, Jai, Narayan, Monishka Rita, Ompong, David, Kobayashi, Takashi, Nagase, Takashi, Funahashi, Masahiro, Saeki, Akinori, Mishchenko, A. S., Manaka, Takaaki, Iwamoto, Mitsumasa, Matsui, Hiroyuki, Noguchi, Yutaka, Ishii, Hisao, Jäger, Lars, Schmidt, Tobias D., Brütting, Wolfgang, Zhao, Li, Kim, DaeHyeon, Ribierre, Jean-Charles, Komino, Takeshi, Adachi, Chihaya, Uno, Mayumi, Osaka, Itaru, Takimiya, Kazuo, and Okamoto, Koichi

Subjects
Organic Semiconductors, Optoelectronics, Organic Electronics
Published
2021

50. What Defines a Crystal Structure? Effects of Chalcogen Atoms in 3,7‐Bis(methylchalcogeno)benzo[1,2‐b:4,5‐b′]dichalcogenophene‐Based Organic Semiconductors†.

Author

Takimiya, Kazuo, Bulgarevich, Kirill, Sahara, Kamon, Kanazawa, Kiseki, Takenaka, Hiroyuki, and Kawabata, Kohsuke

Subjects
*CRYSTAL structure, *ATOMS, *ORGANIC semiconductors, *INTERMOLECULAR interactions, *CRYSTAL growth, *ELECTRONIC structure
Abstract

Comprehensive Summary: To understand the effects of chalcogen atoms on the crystal structure of the series of 3,7‐bis(methylchalcogeno)benzo[1,2‐b:4,5‐b′]dichalcogenophene‐based organic semiconductors, three benzodifuran derivatives (1—3) and dimethoxy derivatives of benzodithiophene and benzodiselenophene (4 and 7) were newly synthesized to complete the "3 × 3 matrix" of the oxygen‐, sulfur‐, and selenium‐derivatives (1—9). The crystal structures of 1—9 were classified into four classes, sandwich pitched π‐stack (1), dimeric (2 and 3), pitched π‐stack (4, 5, 7, 8, 9), and brickwork structure (6 and 9). The causes for the different crystal structures depending on the chalcogen atoms were investigated by the theoretical calculations, indicating that the chalcogen atoms in the core and substituents primarily affected the packing structures. Although the crystal growth in the vapor phase afforded different polymorphs, the relationship between the crystal structure and the carrier transport property was carefully investigated. With these comprehensive evaluations, we conclude that; i) methylchalcogenolation is a powerful tool to alter the packing structure, ii) each methylchalcogeno group has its features that largely influence the intermolecular interaction and electronic structure in the solid state, and iii) organic semiconductors being crystallizable into appropriate pitched π‐stack structures are promising as high‐performance active materials for FET applications. [ABSTRACT FROM AUTHOR]

Published
2022
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