RIKEN Center for Emergent Matter Science Emergent Molecular Function Research Group

Group Director: Kazuo Takimiya (D.Eng.)

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Research Summary

Our research activity is based upon organic synthesis that can afford new organic materials utilized in optoelectronic devices, such as organic field-effect transistors (OFETs), organic solar cells (organic photovoltaics, OPVs), and organic thermoelectric devices (OTE). To this end, our team develops new organic materials, which can be designed and synthesized in order to have appropriate molecular and electronic structures for target functionalities. Our recent achievements are 1) high-performance molecular semiconductors applicable to OFETs with high mobilities, 2) new non-fullerene acceptors and their OPVs showing high power conversion efficiencies, and 3) new molecular design strategies to control packing structures of organic semiconductors.

Main Research Fields

Chemistry

Related Research Fields

Engineering

Keywords

Organic Semiconductors
Pi-electronic compound
Organic Synthesis
Organic field-effect transistor
Organic thermoelectric materials

Selected Publications

1. K, Takimiya., K, Bulgarevich., K. Kawabata.:
"Crystal-structure control of molecular semiconductors by methylthiolation: towards ultrahigh mobility",
Acc. Chem. Res., 34, 884 (2024).
2. T, Matsuo., K, Kawabata., K, Takimiya.:
"A novel n-type molecular dopant with a closed-shell electronic structure applicable to the vacuum-deposition process",
Adv. Mater. 36, 2311047 (2024).
3. K, Bulgarevich., S, Horiuchi., K, Takimiya.:
"Crystal-structure simulation of methylthiolated peri-condensed polycyclic aromatic hydrocarbons for identifying promising molecular semiconductors: discovery of 1,3,8,10-tetrakis(methylthio)peropyrene showing ultrahigh mobility",
Adv. Mater. 355, 2305548 (2023).
4. K, Bulgarevich., K, Takimiya.:
"Crystal-structure simulation of molecular semiconductors: brickwork-related crystal structures of methylthiolated peri-condensed polycyclic aromatic hydrocarbons",
Mater. Horiz., 10, 5492-5499 (2023).
5. K, Kawabata., K. Takimiya.:
"Quinoidal Acenedichalcogenophenediones for Near-infrared-absorbing Organic Semiconductors: Effects of Chalcogen Atom Substitution on The Physicochemical and Carrier Transport Properties",
Chem. Mater., 35, 7628–7642 (2023).
6. K, Sumitomo., Y, Sudo., K, Kanazawa., K.,Kawabata., K, Takimiya.:
"Enantiopure 2-(2-ethylhexyl)dinaphtho[2,3-b:2’,3’-f]thieno[3,2-b]thiophenes: synthesis, single crystal structure and surprising lack of influence of stereoisomerism on thin-film structure and electronic properties,"
Mater. Horiz., 9, 444-451 (2022).
7. K, Takimiya., Kirill Bulgarevich., M, Abbas., S, Horiuchi., T, Ogaki., K, Kawabata., A, Ablat.:
""Manipulation" of crystal structure by methylthiolation enabling ultrahigh mobility in a pyrene-based molecular semiconductor" ,
Adv. Mater., 33, 2102914 (2021).
8. K, Kawabata., K, Takimiya.:
"Quinoid-aromatic Resonance for Very Small Optical Energy Gaps in Small-molecule Organic Semiconductors: a Naphthodithiophenedione-oligothiophene triad system",
Chem. Eur. J., 27, 15660-15670 (2021).
9. Y, Wang., K, Takimiya.:
"Naphthodithiophenediimide–Bithiopheneimide Copolymers for High-Performance n-Type Organic Thermoelectrics: Significant Impact of Backbone Orientation on Conductivity and Thermoelectric Performance",
Adv. Mater., 32, 2002060 (2020).
10. C, Wang., D, Hashizume., M, Nakano., T, Ogaki., H, Tekenaka., K, Kawabata., K, Takimiya.:
""Disrupt and induce" intermolecular interactions to rationally design organic semiconductor crystals: from herringbone to rubrene- like pitched π-stacking",
Chem. Sci., 11, 1573-1580 (2020).