Institute for Molecular Science

Papers

2022-

• Spatial distribution of triplet excitons formed from charge transfer states at donor/acceptor interface
  Seiichiro Izawa, Masahiro Morimoto, Shigeki Naka  and  Masahiro Hiramoto  
  J. Mater. Chem. A, DOI: https://doi.org/10.1039/D2TA02068H

• Efficient interfacial upconversion enabling bright emission at an extremely low driving voltage in organic light-emitting diodes
  Seiichiro Izawa, Masahiro Morimoto, Shigeki Naka , Masahiro Hiramoto  
  Adv. Opt. Mater., 10, 2101710 (2022), Selected as Front Cover

• Simultaneous Measurement of Photocurrent and Recombination Emission in Organic Solar Cell
  Ji-Hyun Lee , Masahiro Hiramoto and Seiichiro Izawa
  Jpn. J. Appl. Phys., 61, 011001 (2022)

-2021-

• Efficient Solid-State Photon Upconversion Enabled by Triplet Formation at Organic Semiconductor Interface
  Seiichiro Izawa, and Masahiro Hiramoto
  Nat. Photon., 15, 895 (2021)

• Quasi-homoepitaxial Junction of Organic Semiconductors: A Structurally Seamless but Electronically Abrupt Interface between Rubrene and Bis(trifluoromethyl)-dimethyl-rubrene
  Kana Takahashi, Seiichiro Izawa, Naoya Ohtsuka, Atsuto Izumiseki, Ryohei Tsuruta, Riku Takeuchi, Yuki Gunjo, Yuki Nakanishi, Kazuhiko Mase, Tomoyuki Koganezawa, Norie Momiyama, Masahiro Hiramoto, and Yasuo Nakayama
  J. Phys. Chem. Lett, 12, 11430 (2021)

• Lateral-tandem organic photovoltaic cells with carrier transport and generation layers
  Jaseela Palassery Ithikkal, Yusuke Yabara, Shoko Uto, Seiichiro Izawa, Masahiro Hiramoto
  Appl. Phys. Express, 14 101003 (2021)

• Influence of N-Substituents on Photovoltaic Properties of Singly Bay-Linked Dimeric Perylene Diimides
  Seiichiro Izawa, Kentaro Uchida, Mayuko Nakamura, Keisuke Fujimoto, Jérémy Roudin, Ji-Hyun Lee, Toshiyasu Inuzuka, Takumi Nakamura, Masami Sakamoto, Yasuo Nakayama, Masahiro Hiramoto, Masaki Takahashi
  Chem. Eur. J. 27, 14081 (2021)

• Photovoltaic behavior of centimeter-long lateral organic junctions
  Jaseela Palassery Ithikkal, Adrien Girault, Mitsuru Kikuchi, Yusuke Yabara, Seiichiro Izawa, Masahiro Hiramoto
  Appl. Phys. Express, 14 094001 (2021)

• Morphology control and synthesis of afterglow materials with a SrAl2O4 framework synthesized by Surfactant-Template and hydrothermal methods
  Motoshi Sera, Mika Yamamoto, Koji Tomita, Yusuke Yabara, Seiichiro Izawa, Masahiro Hiramoto, Takayuki Nakanishi, Koji Yoshida, Katsura Nishiyama
  Chem. Phys. Lett. 780, 138916 (2021)

• Curved Perylene Diimides Fused with Seven‐Membered Rings
  Keisuke Fujimoto, Seiichiro Izawa, Ayumu Takahashi, Toshiyasu Inuzuka, Kazutaka Sanada, Masami Sakamoto, Yasuo Nakayama, Masahiro Hiramoto, Masaki Takahashi
  Chem. Asian J. 16, 690-695 (2021)

• Experimental observation of the anisotropic of valence band dispersion in the dinaphtho[2,3-b:2’,3’-f]thieno[3,2-b]thiophene (DNTT) single crystal
  Riku Takeuchi, Seiichiro Izawa, Yuri Hasegawa, Ryohei Tsuruta, Takuma Yamaguchi, Matthias Meissner, Shin-ichiro Ideta, Kiyohisa Tanaka, Satoshi Kera, Masahiro Hiramoto, and Yasuo Nakayama
  J. Phys. Chem. C, 125, 2938-2943 (2021)

-2020-

• Development of Perylene-Based Non-Fullerene Acceptors through Bay-Functionalization Strategy
  Keisuke Fujimoto, Masaki Takahashi, Seiichiro Izawa, Masahiro Hiramoto
  Materials, 13, 2148 (2020)

• Donor/Acceptor Photovoltaic Cells Fabricated on p-Doped Organic Single-Crystal Substrates
  Yusuke Yabara, Seiichiro Izawa, Masahiro Hiramoto
  Materials, 13, 2068 (2020)

• Electronic and Crystallographic Examinations of the Homoepitaxially Grown Rubrene Single Crystals
  Yasuo Nakayama, Masaki Iwashita, Mitsuru Kikuchi, Ryohei Tsuruta, Koki Yoshida, Yuki Gunjo, Yusuke Yabara, Takuya Hosokai, Tomoyuki Koganezawa, Seiichiro Izawa, Masahiro Hiramoto
  Materials, 13, 1978 (2020)

• Photoconversion Mechanism at the pn-Homojunction Interface in Single Organic Semiconductor
  Ji-Hyun Lee, Armand Perrot, Masahiro Hiramoto, Seiichiro Izawa
  Materials, 13, 1727 (2020)

• Ultra-Thick Organic Pigment Layer Up to 10 μm Activated by Crystallization in Organic Photovoltaic Cells
  Mikimasa Katayama, Toshihiko Kaji, Satoru Nakao and Masahiro Hiramoto
  Front. Energy Res., 8, 4 (2020)

• Regioselective Bay‐Functionalization of Perylenes Toward Tailor‐Made Synthesis of Acceptor Materials for Organic Photovoltaics
  Keisuke Fujimoto, Seiichiro Izawa, Yusaku Arikai, Shinya Sugimoto, Hirona Oue, Toshiyasu Inuzuka, Naohiro Uemura, Masami Sakamoto, Masahiro Hiramoto, Masaki Takahashi
  ChemPlusChem 85, 285–293 (2020)

-2019-

• Importance of Interfacial Crystallinity to Reduce Open-Circuit Voltage Loss in Organic Solar Cells
  Seiichiro Izawa, Naoto Shintaku, Mitsuru Kikuchi, Masahiro Hiramoto
  Appl. Phys. Lett. 115, 153301 (2019)

• Li@C60 endohedral fullerene as a supraatomic dopant for C60 electron-transporting layers promoting the efficiency of perovskite solar cells
  Hiroshi Ueno, Il Jeon, Hao-sheng Lin, Abhishek Thote, Takafumi Nakagawa, Hiroshi Okada,  Seiichiro Izawa, Masahiro Hiramoto, Hirofumi Daiguji, Shigeo Maruyama, Yutaka Matsuo
  Chem. Commun., 55, 11837-11839 (2019)

• Very low activation energy for carrier generation of surface doped organic single crystals observed by Hall effects
  Mitsuru Kikuchi, Seiichiro Izawa, Nitish Rai, Masahiro Hiramoto
  Appl. Phys. Lett. 115, 113301 (2019)

• Organic pn homojunction solar cell
  Seiichiro Izawa, Armand Perrot, Ji-Hyun Lee, Masahiro Hiramoto
  Org. Electron., 71, 45-49 (2019)

• Doping for Controlling Donor/Acceptor Interfacial Structure in Organic Solar Cells
  Seiichiro Izawa, Masahiro Hiramoto
  Rev. Laser Eng., 47, 151-155 (2019)

• Lateral Alternating Donor/Acceptor Multilayered Junction for Organic Solar Cells
  Mitsuru Kikuchi, Masaki Hirota, Thidarat Kunawong, Yusuke Shinmura, Masahiro Abe, Yuichi Sadamitsu, Aye Myint Moh, Seiichiro Izawa, Masanobu Izaki, Hiroyoshi Naito, Masahiro Hiramoto
  ACS Appl. Energy Mater., 2, 2087–2093 (2019)

• Doped organic single-crystal photovoltaic cells
  Mitsuru Kikuchi, Sureerat Makmuang, Seiichiro Izawa, Kanet Wongravee, Masahiro Hiramoto
  Org. Electron., 64, 92-96 (2019)

-2018-

• Effect of Band Bending and Energy Level Alignment at the Donor/Acceptor Interface on Open-Circuit Voltage in Organic Solar Cells
  Seiichiro Izawa, Naoto Shintaku, Masahiro Hiramoto
  J. Phys. Chem. Lett., 9, 2914–2918 (2018)

• Dawn of Organic Single Crystal Electronics-Hall Effect in Doped Organic Single Crystals
  Masahiro Hiramoto
  Eng. Technol. Open. Acc., 1, 555558 (2018)

• Doping for Controlling Open-Circuit Voltage in Organic Solar Cells
  Naoto Shintaku, Masahiro Hiramoto, Seiichiro Izawa
  J. Phys. Chem. C, 122, 5248–5253 (2018)

• Effect of trap-assisted recombination on open-circuit voltage loss in phthalocyanine/fullerene solar cells.
  Naoto Shintaku, Masahiro Hiramoto, Seiichiro Izawa
  Org. Electron., 55, 69-74 (2018)

-2017-

• Hole- and electron-only transport in ratio-controlled organic co-deposited films observed by impedance spectroscopy
  Naoto Shintaku, Seiichiro Izawa, Kenichiro Takagi, Hiroyoshi Naito, Masahiro Hiramoto
  Org. Electron., 50, 515-520 (2017)

• Hall Effect in Bulk-Doped Organic Single Crystals
  Chika Ohashi, Seiichiro Izawa, Yusuke Shinmura, Mitsuru Kikuchi, Seiji Watase, Masanobu Izaki, Hiroyoshi Naito, and Masahiro Hiramoto
  Adv. Mater., 29, 1605619 (2017)
  

• Single crystal organic photovoltaic cells using lateral electron transport
  Mitsuru Kikuchi, Kenichiro Takagi, Hiroyoshi Naito, and Masahiro Hiramoto
  Org. Electron., 41, 118-121(2017)

-2015-

• Enhancing the photocurrent in high-photovoltage organic solar cells by doping
  Mitsuru Kikuchi, Yusuke Shinmura, Toshihiko Kaji, Takahiro Kono, Yuji Yoshida, and Masahiro Hiramoto
  Jpn. J. Appl. Phys., 54, 111601(2015)

• Effects of doping at the ppm level in Simple n+p-homojunction organic photovoltaic cells
  Chika Ohashi, Yusuke Shinmura, Masayuki Kubo, and Masahiro Hiramoto
  Org. Electron., 27, 151-154 (2015)

• Mapping of band-bending in organic pn-homojunctions
  Yohei Yamashina, Yusuke Shinmura, Norihiro Ishiyama, Toshihiko Kaji, and Masahiro Hiramoto
  J. Appl. Phys., 117, 125501 (2015)

-2014-

• Ionization Sensitization of Doping in Co-deposited Organic Semiconductor Films
  Yusuke Shinmura, Yohei Yamashina, Toshihiko Kaji, and Masahiro Hiramoto
  Appl. Phys. Lett., 105, 183306 (2014)

• Mapping of Band-Bending for Doped C60 Films
  Yusuke Shinmura, Tadashi Yoshioka, Toshihiko Kaji, and Masahiro Hiramoto
  Appl. Phys. Express, 7, 071601 (2014)

• Bandgap Science for Organic Solar Cells
  Masahiro Hiramoto, Masayuki Kubo, Yusuke Shinmura, Norihiro Ishiyama, Toshihiko Kaji, Kazuya Sakai, Toshinobu Ohno, and Masanobu Izaki
  Electronics, 3, 351 (2014)

-2013-

• pn-homojunction organic solar cells formed in phase-separated co-deposited films
  Masayuki Kubo, Toshihiko Kaji, and Masahiro Hiramoto
  Appl. Phys. Lett., 103, 263303 (2013)

• Evaluation of Barrier Width by Low-Frequency Capacitance Measurements for MoO3-doped p-Type C60 Films
  Tadashi Yoshioka, Masayuki Kubo, Norihiro Ishiyama, Toshihiko Kaji, and Masahiro Hiramoto
  Mol. Cryst. Liq. Cryst., 579, 1 (2013)

• Effect of Co-evaporant Induced Crystallization on Needle Growth of Phthalocyanine Thin Films
  Toshihiko Kaji, Satoru Nakao, and Masahiro Hiramoto
  Mol. Cryst. Liq. Cryst., 578, 63 (2013)

• Junction Formation by Doping in H2Pc:C60 Co-Evaporated Films for Solar Cell Application
  Masayuki Kubo, Yusuke Shinmura, Norihiro Ishiyama, Toshihiko Kaji, and Masahiro Hiramoto
  Mol. Cryst. Liq. Cryst., 581, 13 (2013)

• Tandem Organic Solar Cells Formed in Co-deposited Films by Doping
  Norihiro Ishiyama, Masayuki Kubo, Toshihiko Kaji, and Masahiro Hiramoto
  Org. Electron., 14, 1793 (2013)

• Tuning of Barrier Parameters of n-Type Schottky Junctions in Photovoltaic Co-Deposited Films by Doping
  Norihiro Ishiyama, Tadashi Yoshioka, Toshihiko Kaji, and Masahiro Hiramoto
  Appl. Phys. Express, 6, 012301 (2013)

• Improved Photovoltaic Characteristics by MoO3-doping to Thick Hole Transporting Films
  Yusuke Shinmura, Masayuki Kubo, Toshihiko Kaji, and Masahiro Hiramoto
  Jpn. J. Appl. Phys., 52, 04CR12 (2013)

• Double Co-deposited Layered Organic Photovoltaic Cells with Sensitivity Through the Visible to Near-Infrared Regions
  Kazuya Yokoyama, Toshihiko Kaji, and Masahiro Hiramoto
  Jpn. J. Appl. Phys., 52, 04CR06 (2013)

-2012-

• Tandem photovoltaic cells formed in single fullerene films by impurity doping
  Norihiro Ishiyama, Masayuki Kubo, Toshihiko Kaji, and Masahiro Hiramoto
  Appl. Phys. Lett. 101, 233303 (2012)

•  pn-control and pn-homojunction formation of matal-free phthalocyanine by doping
  Yusuke Shinmura, Masayuki Kubo, Norihiro Ishiyama, Toshihiko Kaji, and Masahiro Hiramoto
  AIP Advances 2, 032145 (2012)

• Invertible Organic Photovoltaic Cells with Heavily Doped Organic/Metal Ohmic Contacts
  Masayuki Kubo, Yusuke Shinmura, Norihiro Ishiyama, Toshihiko Kaji, and Masahiro Hiramoto
  Appl. Phys. Express 5, 092302 (2012)

-2011-

• pn-homojunction formation in single fullerene films
  Masayuki Kubo, Toshihiko Kaji, and Masahiro Hiramoto
  AIP Advances 1(3), 032177 (2011)

• Doping-based control of the energetic structure of photovoltaic co-deposited films
  Norihiro Ishiyama, Masayuki Kubo, Toshihiko Kaji, and Masahiro Hiramoto
  Appl. Phys. Lett. 99(13), 133301 (2011)

• Co-evaporant Induced Crystalline Donor: Acceptor Blends in Organic Solar Cells
  Toshihiko Kaji,* Minlu Zhang , Satoru Nakao , Kai Iketaki , Kazuya Yokoyama , Ching W. Tang , and Masahiro Hiramoto
  Adv. Mater. 23(29), 3320-3325 (2011)

• Conduction-type control of fullerene films from n- to p-type by molybdenum oxide doping
  Masayuki Kubo, Kai Iketaki, Toshihiko Kaji, and Masahiro Hiramoto
  Appl. Phys. Lett. 98(7), 073311 (2011)

• Near infrared light driven organic p-i-n solar cells incorporating phthalocyanine J-aggregate
  Masahiro Hiramoto, Keitaro Kitada, Kai Iketaki, and Toshihiko Kaji
  Appl. Phys. Lett. 98(2), 023302 (2011)

• Structural Studies of the Codeposited i-Layer of ZnPc:C₆₀ p-i-n Solar Cells
  Kai Iketaki, Toshihiko Kaji, Satoru Nakao, and Masahiro Hiramoto
  Physica Status Solidi C, 8 (No. 2), 637-639 (2011)

-2010-

• Morphology of Rare-Earth (Y, Sm) Nanostructures Synthesized by the Surfactant-Assenbled Method
  Katsura Nishiyama, Takashi Hanamoto, Hirotake Shigematsu, Keitaro Kitada, Kai Iketaki, Toshihiko Kaji, and Masahiro Hiramoto
  Chem. Lett., 39(9), 974-976 (2010)

• One Month Continuous Operation of Organic p-i-n Solar Cells Covered with a Zinc Oxide Protection Layer
  Masahiro Hiramoto and Hiroki Shiokawa
  Appl. Phys. Express, 3, 082301 (2010)

-2008-

• Efficient organic p-i-n solar cells having very thick codeposited i-layer composed of highly purified organic semiconductors
  M. Hiramoto
  Proceedings of SPIE Vol. 7052, Organic photovoltaics IX, pp 70520H-1-6 , San Diego, CA, USA, 12-14 Augst (2008). [Invited]

• Nanostructure control by interlaminated fullerene/phthalocyanine ultrathin films in p-i-n organic solar cells
  H. Shiokawa, M. Hiramoto
  Mol. Cryst. Liq. Cryst., 491, 277-283 (2008)

• Efficient organic p-i-n solar cells having very thick codeposited i-layer consisting of highly purified organic semiconductors
  K. Sakai, M. Hiramoto
  Mol. Cryst. Liq. Cryst., 491, 284-289 (2008)

-2007-

• Long-term operation tests of organic solid-state solar cells
  H. Shiokawa, M. Yokoyama, M. Hiramoto
  Surface Review and Letters, 14(4), 539-542 (2007)

• Formation of Ohmic Contacts to Naphthalene Tetracarboxylic Anhydride Films
  K. W. Yee, K. Suemori, M. Yokoyama, and M. Hiramoto
  Mol. Cryst. Liq. Cryst., 462, 45-50 (2007)

-2006-

• 直立超格子による有機ELナノ構造設計
  平本昌宏、團野まり、横山正明
  高分子論文集、63(No. 10), 670-674 (2006)

• Design of Nanostructure for Photo-electric Conversion by Organic Vertical Superlattice
  Masahiro Hiramoto, Takumi Yamaga, Mari Danno, Kouji Suemori, Yoshio Matsumura, and Masaaki Yokoyama
  Appl. Phys. Lett., 88, 213105, (2006)

• P-I-N Juction Organic Solar Cells
  Masahiro Hiramoto
  Mol. Cryst. Liq. Cryst., 455, 267-275 (2006)

• Formation of Ohmic Contacts to Organic Semiconductor Films
  Masahiro Hiramoto, Yee Kok Wei, kouji Suemori, and Masaaki Yokoyama
  Mol. Cryst. Liq. Cryst., 455, 333-338 (2006)

• Large Area Organic Solar Cells with Thick and Transparent Protection Layers
  Kouji Suemori, Yoshio Matsumura, Masaaki Yokoyama, Masahiro Hiramoto
  Jpn. J. Appl. Phys., 45(17), L472-L474 (2006)

• Very-thin-perylene-crystal-based electroluminescent devices
  Kok Wei Yee, Masaaki Yokoyama, Masahiro Hiramoto
  Appl. Phys. Lett., 88, 083511 (2006)

• Electrical Shorting of Organic Photovoltaic Films Resulting from Metal Migration
  Kouji Suemori, Masaaki Yokoyama, Masahiro Hiramoto
  J. Appl. Phys., 99, 036109 (2006). [Virtual Journal of Nanoscale Science & Technology, Feb. 27 2006 issue に転載]

• Organic Solar Cells incorporating a p-i-n junction
  Masahiro Hiramoto, Kouji Suemori, and Masaaki Yokoyama
  Mol. Cryst. Liq. Cryst., 444, 33-40 (2006)

-2005-

• 直立有機超格子による光電変換ナノ構造設計
  平本昌宏
  電子情報通信学会(IEICE）論文誌C, Vol. J88-C (No. 9) pp686-691, (2005)（招待論文）

• Formation of Ohmic Contacts Both for Holes and Electrons to Organic Semiconductor Films
  Kouji Suemori, Masaaki Yokoyama, and Masahiro Hiramoto
  Appl. Phys. Lett., 86, 173505 (2005)

• Three-layered Organic Solar Cells Incorporating Nanostructure-optimized Phthalocyanine:Fullerene Codeposited Interlayer
  Kouji Suemori, Takahiro Miyata, Masaaki Yokoyama, and Masahiro Hiramoto
  Appl. Phys. Lett., 86(6), 063509 (2005)

-2004-

• Organic Solar Cells Protected by Very Thick Naphthalene Tetracarboxylic Anhydride Films
  Kouji Suemori, Takahiro Miyata, Masaaki Yokoyama, and Masahiro Hiramoto
  Appl. Phys. Lett., 85(25), 6269-6271 (2004)

• Formation of Ohmic Contacts to Perylene Molecular Crystals
  Masahiro Hiramoto, Akinori Tomioka, Kouji Suemori, and Masaaki Yokoyama
  Appl. Phys. Lett., 85(10),  1852-1854 (2004)

• Vertical Junction Type Organic Photovoltaic Cells
  Kouji Suemori, Takahiro Miyata, Masahiro Hiramoto, Masaaki Yokoyama
  Jpn. J. Appl. Phys., 43 (No. 8B), L1094-L1096 (2004)

• Optical “NOT” Operation in a Light Transducer in which a High-gain Photoresponsive Organic Heterojunction Device is Combined with an Organic Electroluminescent Diode
  Masahiro Hiramoto, Yoshihito Motohashi, Norio Nagayama, Hiroyuki Kumaoka, and Masaaki Yokoyama
  Jpn. J. Appl. Phys., 43 (No. 8A, Express Letter), L1041-L1043 (2004)

• Enhanced Photovoltaic Performance in Fullerene:Phthalocyanine Co-deposited Films Deposited on Heated Substrate
  Kouji Suemori, Takahiro Miyata, Masahiro Hiramoto, Masaaki Yokoyama
  Jpn. J. Appl. Phys., 43 (No. 8A), L1014-L1016 (2004)

• Crystalline-Amorphous Organic Co-deposited Films Showing Efficient Photo-electric Conversion
  Kouji Suemori, Takahiro Miyata, Yuko Oishi, Masahiro Hiramoto, and Masaaki Yokoyama
  Mol. Cryst. Liq. Cryst., 425, 181-188 (2004)

-2003-

• Influence of Oxygen on Photocurrent Multiplication Phenomenon at Organic/Metal Interface
  Masahiro Hiramoto, Kouji Suemori, and Masaaki Yokoyama
  Jpn. J. Appl. Phys., 42(No. 4B), 2495-2497 (2003)

• Influence of Oxygen and Water on Photocurrent Multiplication in Organic Semiconductor Films
  Masahiro Hiramoto, Kentaro Fujino, Manabu Yoshida, and Masaaki Yokoyama
  Jpn. J. Appl. Phys., 42(No. 2A), 672-675 (2003)

-2002-

• Photocurrent Multiplication in Organic Single Crystals
  Masahiro Hiramoto, Ayako Miki, Manabu Yoshida, and Masaaki Yokoyama
  Appl. Phys. Lett., 81(8), 1500-1502 (2002)

• High-speed Multiplication-type Photodetecting Device Using Organic Co-deposited Films
  Goh Matsunobu, Yuko Oishi, Masaaki Yokoyama, and Masahiro Hiramoto
  Appl. Phys. Lett., 81(7), 1321-1322 (2002)

• Metal Nanostructure of Metal/Organic Interface Causing Photocurrent Multiplication Phenomenon
  Masahiro Hiramoto, Ichiro Sato, and Masaaki Yokoyama
  IEICE Transactions on Electronics, E85-C (6), 1253-1255 (2002)

• Photovoltaic Properties of Ultramicrostructure-Controlled Organic Co-deposited Films
  Masahiro Hiramoto, Kouji Suemori, and Masaaki Yokoyama
  Jpn. J. Appl. Phys., 41, 2763-2766 (2002)

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