Faculty Profiles - MATSUO Yutaka

Papers - MATSUO Yutaka

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Structure of [60]fullerene with a mobile lithium cation inside Reviewed

Aoyagi Shinobu, Miwa Kazuhira, Ueno Hiroshi, Okada Hiroshi, Matsuo Yutaka, Kokubo Ken

ROYAL SOCIETY OPEN SCIENCE Vol. 5 ( 7 ) 2018.7

Polymeric Acid-doped Transparent Carbon Nanotube Electrodes for Organic Solar Cells with the Longest Doping Durability Reviewed International coauthorship

Il Jeon, Clement Delacou, Hiroshi Okada, Graham E. Morse, Tae-Hee Han, Yuta Sato, Anton Anisimov, Kazu Suenaga, Esko I. Kauppinen, Shigeo Maruyama, Yutaka Matsuo

Journal of Materials Chemistry A Vol. 6 ( 30 ) page： 14553 - 14559 2018.6

Fullerene-Cation-Mediated Noble-Metal-Free Direct Introduction of Functionalized Aryl Groups onto [60]Fullerene Reviewed

Xiao-Yu Yang, Hao-Sheng Lin, Il Jeon, Yutaka Matsuo

Organic Letters Vol. 20 ( 11 ) page： 3372 - 3376 2018.6

Language：English Publishing type：Research paper (scientific journal) Publisher：American Chemical Society

Aryl[60]fullerenyl cations (ArC60 +), which were generated by heating aryl[60]fullerenyl dimers (ArC60-C60Ar) to generate aryl[60]fullerenyl radicals (ArC60 •) followed by oxidation using Cu(II) salts (Cu(BF4)2(aq)), were reacted with various functionalized aryl boronic acids to produce functionalized 1,4-diaryl[60]fullerenes. This protocol tolerated various functional groups, such as OH, NH2, COCH3, and Cl substituents, with yields reaching 93%. C60Ar1Ar2 (Ar2 = p-NH2C6H4) was used as a dopant in a photoactive CH3NH3PbI3 layer of a perovskite solar cell.

DOI： 10.1021/acs.orglett.8b01295

Lithium-Ion Endohedral Fullerene (Li+@C-60) Dopants in Stable Perovskite Solar Cells Induce Instant Doping and Anti-Oxidation

Jeon Il, Ueno Hiroshi, Seo Seungju, Aitola Kerttu, Nishikubo Ryosuke, Saeki Akinori, Okada Hiroshi, Boschloo Gerrit, Maruyama Shigeo, Matsuo Yutaka

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Vol. 57 ( 17 ) page： 4607 - 4611 2018.4

Engineering High-performance and Air-stable PBTZT-stat-BDTT-8:PC61BM/PC71BM Organic Solar Cells Reviewed International coauthorship

Il Jeon, Ryohei Sakai, Seungju Seo, Graham E. Morse, Hiroshi Ueno, Takafumi Nakagawa, Yang Qian, Shigeo Maruyama, Yutaka Matsuo

Journal of Materials Chemistry A Vol. 6 ( 14 ) page： 5746 - 5751 2018.4

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry

High-performance air-stable PBTZT-stat-BDTT-8 organic solar cells were fabricated using mixed C60/C70 fullerene acceptors. Normal-architecture devices using PBTZT-stat-BDTT-8 with PC71BM produced a power conversion efficiency (PCE) of 9.38%. An inverted-architecture, which possesses higher stability, was fabricated using a more economical PC61BM and PC71BM mixture with solution-processed PEDOT:PSS on top and produced a PCE of 8.15%. Exploiting the viscous nature of PBTZT-stat-BDTT-8, the slow evaporation effect was utilised to achieve an even higher efficiency of 8.73%. A stability test was conducted under operating conditions and our devices showed remarkably higher stability compared with PTB7-based devices.

DOI： 10.1039/c7ta11095b

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Anthracene-Based Organic Small-Molecule Electron-Injecting Material for Inverted Organic Light-Emitting Diodes Reviewed

Yutaka Matsuo, Hiroshi Okada, Yasuhiro Kondo, Il Jeon, Huan Wang, Yun Yu, Takeshi Matsushita, Motoki Yanai, Toshiaki Ikuta

ACS Applied Materials and Interfaces Vol. 10 ( 14 ) page： 11810 - 11817 2018.4

Language：English Publishing type：Research paper (scientific journal) Publisher：American Chemical Society

A diphenylanthracene dimethylamine derivative (9-{3,5-di(N,N-dimethylaminoethoxy)phenyl}-10-phenyl-anthracene, DPAMA) was synthesized by the Suzuki-Miyaura cross-coupling reaction. Its ammonium salt, 9-{3,5-di(trimethylammonium ethoxy)phenyl}-10-phenyl-anthracene dichloride (DPAMA-Cl), was also synthesized as a reference material. DPAMA was characterized by UV-vis and fluorescence spectroscopy, cyclic voltammetry, photoelectron yield spectroscopy, and X-ray photoelectron spectroscopy to evaluate the work function-modifying ability of DPAMA on indium tin oxide (ITO) and ZnO. The work functions of ITO and ZnO changed from 4.4 and 4.0 eV (pristine) to 3.8 and 3.9 eV, respectively. Using this surface modification effect of DPAMA, inverted organic light-emitting diodes were fabricated with device structures of ITO/DPAMA/Alq3/NPD/MoO3/Al (Alq3 = tris(8-hydroxyquinolinato)aluminum
NPD = N,N′-di-[(1-naphthyl)-N,N′-diphenyl]-1,1′-(biphenyl)-4,4′-diamine) and ITO/ZnO/DPAMA/Alq3/NPD/MoO3/Al. Both devices showed good performance at the range of current density, 1-300 mA/cm2. The best inverted organic light-emitting diodes device showed luminance of 7720 cd/m2, current efficiency of 4.51 cd/A, and external quantum efficiency of 1.45%. Also, poly(3-hexylthiophene):mixed phenyl-C61 and C71 butyric acid methyl ester-based organic solar cells using DPAMA and DPAMA-Cl as electron-transporting materials showed power conversion efficiencies of 3.3 and 3.4%, respectively.

DOI： 10.1021/acsami.8b00603

Lithium-Ion Endohedral Fullerene (Li+@C60) Dopants in Stable Perovskite Solar Cells Induce Instant Doping and Anti-Oxidation Reviewed International coauthorship

Il Jeon, Hiroshi Ueno, Seungju Seo, Kerttu Aitola, Ryosuke Nishikubo, Akinori Saeki, Hiroshi Okada, Gerrit Boschloo, Shigeo Maruyama, Yutaka Matsuo

Angewandte Chemie International Edition Vol. 130 ( 17 ) page： 4697 2018.3

Carbon-sandwiched perovskite solar cell Reviewed

Namyoung Ahn, Il Jeon, Jungjin Yoon, Esko I. Kauppinen, Yutaka Matsuo, Shigeo Maruyama, Mansoo Choi

Journal of Materials Chemistry A Vol. 6 ( 4 ) page： 1382 - 1389 2018.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry

Promising perovskite solar cell technology with soaring power conversion efficiencies has the common problems of low stability and high cost. This work provides a solution to these problems by employing a carbon sandwich structure, in which the fullerene bottom layer solves the stability issue and the carbon nanotube top electrode layer offers the merits of having high stability and being low-cost. Devices fabricated using different hole-transporting materials infiltrated into carbon nanotube networks were examined for their performance and stability under constant illumination in air. Polymeric hole-transporting layers show much higher stability when combined with carbon nanotubes due to their compact nature and stronger interaction with the carbon network. As a result, the encapsulated device showed high stability both in air and under light illumination, maintaining up to 80% of the initial efficiency after 2200 hours under actual operation conditions. Cost analysis also shows that using the polymeric hole-transporting materials in carbon nanotube films brings the fabrication cost down to less than 5.5% that of conventional devices. Our study proposes a promising cell structure toward highly stable and low-cost perovskite photovoltaic technologies for the future.

DOI： 10.1039/c7ta09174e

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A Helically-Twisted Ladder Based on 9,9'-Bifluorenylidene: Synthesis, Characterization, and Charge Transport Properties Reviewed

Jinjia Xu, Atsuro Takai, Alisa Bannaron, Takafumi Nakagawa, Yutaka Matsuo, Manabu Sugimoto, Yoshitaka Matsushita, Masayuki Takeuchi

Materials Chemistry Frontiers Vol. 2 page： 780 - 784 2018.1

A fluorenylidene-acridane that becomes dark in color upon grinding-ground state mechanochromism by conformational change Reviewed

Tsuyoshi Suzuki, Hiroshi Okada, Takafumi Nakagawa, Kazuki Komatsu, Chikako Fujimoto, Hiroyuki Kagi, Yutaka Matsuo

Chemical Science Vol. 9 ( 2 ) page： 475 - 482 2018.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry

We report mechanochromic color change controlled by conformational change (between folded and twisted conformers) of fluorenylidene-acridanes (FAs). FAs with four N-alkyl groups (methyl, ethyl, n-butyl and n-octyl) were synthesized via the Barton-Kellogg reaction of diazofluorene and electrophilic N-tert-butoxy carbonyl thioacridone, deprotection of the tert-butoxy carbonyl group gives fluorenylacridine, and alkylation on the nitrogen atom is done using alkyl tosylate or triflate. FAs were characterized by NMR, UV-vis absorption and photoluminescence spectroscopy, theoretical calculation, cyclic voltammetry, and powder and single-crystal X-ray analyses. The color and folded/twisted conformation of the FAs were changed by the choice of substituent on the nitrogen atom, physical state (solution or solid), and morphology (crystalline or amorphous). Grinding of N-methyl FA solids, using an agate mortar, caused the morphology to change from a crystalline to amorphous state, which induced a conformational change from the folded to the twisted conformer, and a mechanochromic color change from yellow to dark green. The reverse color change, along with a morphological and conformational change to the folded conformer, was performed by solvent vapor exposure (chloroform). The twisted and folded conformers showed ambipolar (hole/electron) and hole-only transport properties, respectively.

DOI： 10.1039/c7sc03567e

Non-doped and unsorted single-walled carbon nanotubes as carrier-selective, transparent, and conductive electrode for perovskite solar cells Reviewed International coauthorship

Takahiro Sakaguchi, Il Jeon, Takaaki Chiba, Ahmed Shawky, Rong Xiang, Shohei Chiashi, Esko I. Kauppinen, Nam-Gyu Park, Yutaka Matsuo, Shigeo Maruyama

MRS Communications Vol. 8 ( 3 ) page： 1058 - 1063 2018

Substituent effects in magnesium tetraethynylporphyrin with two diketopyrrolopyrrole units for bulk heterojunction organic solar cells Reviewed

Ogumi Keisuke, Nakagawa Takafumi, Okada Hiroshi, Sakai Ryohei, Wang Huan, Matsuo Yutaka

JOURNAL OF MATERIALS CHEMISTRY A Vol. 5 ( 44 ) page： 23067 - 23077 2017.11

Comparative density functional theory-density functional tight binding study of fullerene derivatives: effects due to fullerene size, addends, and crystallinity on band structure, charge transport and optical properties Reviewed

Amrita Pal, Lai Kai Wen, Chia Yao Jun, Il Jeon, Yutaka Matsuo, Sergei Manzhos

PHYSICAL CHEMISTRY CHEMICAL PHYSICS Vol. 19 ( 41 ) page： 28330 - 28343 2017.11

Language：English Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY

We present a systematic comparative density functional theory-density functional tight binding study of multiple derivatives of C60 and C70 with different addends, in molecular as well as solid state. In particular, effects due to fullerene size, type and number of addends, and of crystallinity on band structure, charge transport, and optical properties are investigated. These are important, in particular, for rational selection of fullerene derivatives as acceptor and electron transport layers in organic as well as planar inverted perovskite solar cells. We find that by the choice of type and number of addends, one can modulate the LUMO within 0.4 eV. Changes in the HOMO can reach 0.7 eV. Substituting C70 for C60 results in destabilization of the HOMO by about 0.1 eV for indene and quinodimethane addends and by a less significant amount for PCBM addends. The effect of C70-C60 substitution on the LUMO is of similar magnitude. A more significant change in HOMO-LUMO energy is seen for the aryl addends. On the other hand, all C70 based molecules have strong visible absorption. For most addends, the crystal packing leads to a stabilization of both the LUMO and HOMO by about similar to 0.2 and similar to 0.1 eV, respectively, vs. single molecules. When using bis-addends, it is also possible to enhance the visible absorption. Electron and hole transport rates are computed to vary vastly depending on the addends chosen; specifically, we compute that indene and quimodimethane addends can enhance charge transport rates while the aryl addend is predicted to result in substantially smaller mobilities of electrons and holes, vs. PC60BM. Furthermore, the -CH2 and bisaddend addition can significantly enhance the charge transfer rates for the PCBM addend.

DOI： 10.1039/c7cp05290a

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Carbon Nanotubes versus Graphene as Flexible Transparent Electrodes in Inverted Perovskite Solar Cells Reviewed International coauthorship

Il Jeon, Jungjin Yoon, Namyoung Ahn, Mohamed Atwa, Clement Delacou, Anton Anisimov, Esko I. Kauppinen, Mansoo Choi, Shigeo Maruyama, Yutaka Matsuo

Journal of Physical Chemistry Letters Vol. 8 ( 21 ) page： 5395 - 5401 2017.11

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

Transparent carbon electrodes, carbon nanotubes, and graphene were used as the bottom electrode in flexible inverted perovskite solar cells. Their photovoltaic performance and mechanical resilience were compared and analyzed using various techniques. Whereas a conventional inverted perovskite solar cells using indium tin oxide showed a power conversion efficiency of 17.8%, the carbon nanotube- and graphene-based cells showed efficiencies of 12.8% and 14.2%, respectively. An established MoO3 doping was used for carbon electrode-based devices. The difference in the photovoltaic performance between the carbon nanotube- and graphene-based cells was due to the difference in morphology and transmittance. Raman spectroscopy, and cyclic flexural testing revealed that the graphene-based cells were more susceptible to strain than the carbon nanotube-based cells, though the difference was marginal. Overall, despite higher performance, the transfer step for graphene has lower reproducibility. Thus, the development of better graphene transfer methods would help maximize the current capacity of graphene-based cells.

DOI： 10.1021/acs.jpclett.7b02229

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Perovskite Solar Cells Using Carbon Nanotubes Both as Cathode and as Anode Reviewed International coauthorship

Il Jeon, Seungju Seo, Yuta Sato, Clement Delacou, Anton Anisimov, Kazu Suenaga, Esko I. Kauppinen, Shigeo Maruyama, Yutaka Matsuo

JOURNAL OF PHYSICAL CHEMISTRY C Vol. 121 ( 46 ) page： 25743 - 25749 2017.11

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

Organic-inorganic halide perovskite solar cells have received much attention because they achieve high power conversion efficiencies while providing the advantages of thin-film solar cells, namely, solution processability and potentially low fabrication costs. However, at the current level of halide perovskite solar cell technology, these advantages cannot be maximized because of structural and material limitations. Here, we provide a solution to these problems by replacing conventional metal and metal oxide electrodes with carbon nanotube electrodes. We also simplified the structure to achieve entirely solution-processable perovskite solar cells. Through this study, we demonstrate the function of carbon nanotubes as both the anode and the cathode in perovskite solar cells. Economic modeling suggests that this novel architecture reduces costs dramatically. This work realizes innovations in the materials, costs, and processing of inverted-type perovskite solar cells.

DOI： 10.1021/acs.jpcc.7b10334

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Synthesis and Crystal Structure of Li+@Fluoreno[60]fullerene: Effect of Encapsulated Lithium Ion on Electrochemistry of Spiroannelated Fullerene Reviewed International coauthorship

Hiroshi Ueno, Hiroshi Okada, Shinobu Aoyagi, Yutaka Matsuo

Journal of Organic Chemistry Vol. 82 page： 11631 - 11635 2017.10

Highly Conductive and Transparent Large-Area Bilayer Graphene Realized by MoCl5 Intercalation Reviewed

Hiroki Kinoshita, Il Jeon, Mina Maruyama, Kenji Kawahara, Yuri Terao, Dong Ding, Rika Matsumoto, Yutaka Matsuo, Susumu Okada, Hiroki Ago

Advanced Materials Vol. 29 ( 41 ) page： 1702141 2017.9

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

Bilayer graphene (BLG) comprises a 2D nanospace sandwiched by two parallel graphene sheets that can be used to intercalate molecules or ions for attaining novel functionalities. However, intercalation is mostly demonstrated with small, exfoliated graphene flakes. This study demonstrates intercalation of molybdenum chloride (MoCl5 ) into a large-area, uniform BLG sheet, which is grown by chemical vapor deposition (CVD). This study reveals that the degree of MoCl5 intercalation strongly depends on the stacking order of the graphene; twist-stacked graphene shows a much higher degree of intercalation than AB-stacked. Density functional theory calculations suggest that weak interlayer coupling in the twist-stacked graphene contributes to the effective intercalation. By selectively synthesizing twist-rich BLG films through control of the CVD conditions, low sheet resistance (83 Ω ▫(-1) ) is realized after MoCl5 intercalation, while maintaining high optical transmittance (≈95%). The low sheet resistance state is relatively stable in air for more than three months. Furthermore, the intercalated BLG film is applied to organic solar cells, realizing a high power conversion efficiency.

DOI： 10.1002/adma.201702141

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Regiocontrolled Electrosynthesis of [60]Fullerene Bisadducts: Photovoltaic Performance and Crystal Structures of C-60 o-Quinodimethane Bisadducts Reviewed International coauthorship

Zong-Jun Li, Sisi Wang, Shu-Hui Li, Tao Sun, Wei-Wei Yang, Kazutaka Shoyama, Takafumi Nakagawa, Il Jeon, Xiaoniu Yang, Yutaka Matsuo, Xiang Gao

JOURNAL OF ORGANIC CHEMISTRY Vol. 82 ( 16 ) page： 8676 - 8685 2017.8

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

C-60 o-quinodimethane bisadducts [C-60(QM)(2)] are promising electron acceptors for bulk heterojuction (BHJ) organic solar cells (OSCs). However, previous production of C-60(QM)(2) often resulted in excessive regioisomers, which were difficult to purify and might consequently obscure the structure performance study of the organofullerene acceptors. Herein, the electrosynthesis of C-60(QM)(2) is reported. The reaction exhibits a strong regiocontrol with generation of fewer regioisomers. Pure regioisomers of cis-2, trans-3, and e C-60(QM)(2) are obtained, and the structures are solved with single-crystal X-ray diffraction. Interestingly, the cis-2 and trans-3 regioisomers exhibit better photovoltaic performance than the e regioisomer in the OSCs based on poly(3-hexylthiophene) (P3HT), which can be correlated with their structural difference.

DOI： 10.1021/acs.joc.7b01732

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Crystallographic Structure Determination of Both [5,6]- and [6,6] Isomers of Lithium-Ion-Containing Diphenylmethano[60]fullerene Reviewed

Hiroshi Okada, Hiroki Kawakami, Shinobu Aoyagi, Yutaka Matsuo

JOURNAL OF ORGANIC CHEMISTRY Vol. 82 ( 11 ) page： 5868 - 5872 2017.6

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

Organic functionalization of lithium-ion-containing [60]fullerene, Li+@C-60, was performed by using diphenyl(diazo)methane as a stable, readily available diazo compound to obtain lithium-ion-containing [5,6]- and [6,6]-diphenylmethano[60]fullerenes, Li+@C61Ph2. The bis(trifluoromethanesulfonyl)imide (TFSI) salts of [5,6]- and [6,6]-Li+@C61Ph2 were successfully separated by using a cation exchange column with eluent containing LiTFSI. Improved separation protocol and high crystallinity of ionic components in less polar solvents enabled separate crystallization of each isomer. Both [5,6]-open and [6,6]-closed structures of Li+@C61Ph2 were determined by synchrotron radiation X-ray crystallography. Elucidating the [5,6] -open methano[60]fullerene (fulleroid) structure will contribute to materials research on fulleroids.

DOI： 10.1021/acs.joc.7b00730

Scalable and Solid-state Redox Functionalization of Transparent Single-walled Carbon Nanotube Films for Highly Efficient and Stable Solar Cells Reviewed International coauthorship

Kehang Cui, Yang Qian, Il Jeon, Anton Anisimov, Yutaka Matsuo, Esko I. Kauppinen, Shigeo Maruyama

Advanced Energy Materials Vol. 7 page： 1700449 2017.5

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Papers - MATSUO Yutaka