PUBLICATIONS

2020.10.06

2025

113.　A Strategically Designed Easily-Synthesized Polymer Donor for Efficient Organic 　Photovoltaics”, Kodai Yamanaka, Tsubasa Mikie, and ItaruOsaka*, Adv. Energy Mater. 2025, 2502173. https://advanced.onlinelibrary.wiley.com/doi/10.1002/aenm.202502173

2024

  1. Controlling theThermoelectric Performance of Doped Naphthobisthiadiazole-Based Donor–Acceptor Conjugated Polymers through Backbone Engineering
    J-F. Ding, K. Yamanaka, S.-H. Hong, G-L. Chen, W.-N. Wu, J.-M. Lin, S.-H. Tung, I. Osaka,* C.-L. Liu*
    Advanced Science, 2024, 10046.
  1. Dithienonaphthobisthiadiazole synthesized by thienannulation of electron-deficient rings: an acceptor building unit for high-performance π-conjugated polymers
    T. Mikie, T. Morioku, S. Suruga, M. Hada, Y.Sato, H. Ohkita, I.Osaka
    Chemical Science, 2024, 15, 19991-20001.
  1. Efficient Derivatization of a Thienobenzobisthiazole-Based π-Conjugated Polymer Through Late-Stage Functionalization Towards High-Efficiency Organic Photovoltaic Cells
    H. Iwasaki, K. Yamanaka, Y. Sato, T. Mikie, M. Saito, H. Ohkita, I. Osaka*
    Angew. Chem. Int. Ed., 2024, 63, e202409814.
  1. Photon Energy Loss in Ternary Polymer Solar Cells Based on Nonfullerene Acceptor as a Third Component
    J. Jeon, S. Hosoya, M. Saito, I. Osaka, H. Ohkita,* H.-D, Kim*
    Battey Energy, 2024, 3, 20240011.
  1. Synthesis of indano [60] fullerene thioketone and its application in organic solar cells
    Y.-C. Zhai, S. Oiwa, S. Aoyagi, S. Ohno, T. Mikie, J.-Z. Wang, H. Amada, K. Yamanaka, K. Miwa, N. Imai, T. Igarashi, I. Osaka, Y. Matsuo*
    Beilstein Journal of Organic Chemistry, 2024, 20, 1270-1277.
  1. Two Isomeric Benzo[d]imidazole-Based Nonfullerene Acceptors for Organic Photovoltaics　
    S. Ono, T. Mikie*, K. Nakano, K. Tajima, I. Osaka*
    ACS Appl. Energy Mater. 2024, 7, 2946–2954.
  1. Bending the Rule: Naphthobisthiadiazole-Based Terpolymers with Both High Solubility and Crystallinity for Organic Photovoltaics　
    L-H. Chou, F. Chen, K. Nakano, K. Yamanaka, T. Mikie, M. Saito, C-L. Liu, K. Tajima*, I. Osaka*
    ACS Appl. Polym. Mater. 2024, 6, 2586–2593.
  1. A highly crystalline face-on 𝝅-conjugated polymer based on alkoxythiophene-flanked benzobisthiazole for organic photovoltaics　
    S. Doi, T. Mikie, K. Yamanaka, Y. Sato, H. Ohkita, M. Saito, I. Osaka
    Polymer Journal, 2024, 56, 1051–1059.
  1. Twisted diphenoquinones fused with thiophene rings: thiophene analogs of bianthrone　
    Y. Adachi, Y. Hattori, T. Mikie, I. Osaka, J. Ohshita
    Chem. Commun., 2024, 60, 10410-10413
  1. Manipulating the functionality and structures of π-conjugated polymers utilizing intramolecular noncovalent interactions towards efficient organic photovoltaics　
    S. Kamimura, M. Saito, Y. Teshima, K. Yamanaka, H. Ichikawa, A. Sugie, H. Yoshida, J. Jeon, H. D. Kim, H. Ohkita, T. Mikie, I. Osaka
    Chem. Sci., 2024, 15, 6349-6362.
  1. Employment of Alkoxy Sidechains in Semicrystalline Semiconducting Polymers for Ambient-Stable p-Doped Conjugated Polymers　
    T. Kurosawa, Y. Yamashita, Y. Kobayashi, C. P Yu, S. Kumagai, T. Mikie, I. Osaka, S. Watanabe, J. Takeya, T. Okamoto
    Macromolecules, 2024, 57, 328–338.
  1. Simple π-Conjugated Polymers Based on Bithiazole for Nonfullerene Organic Photovoltaics
    Y. Teshima, K. Yamanaka, Y. Sato, H. Ohkita, T. Mikie, M. Saito, and I. Osaka*
    ACS Appl. Mater. Interfaces, 2024, 16, 3735–3743.

2023

  1. Ordered π-conjugated polymer backbone in amorphous blend for high efficiency nonfullerene organic photovoltaics
    M. Saito, H. Yamada, K. Kranthiraja, T. Mikie, A. Saeki*, H. Ohkita*, I. Osaka*
    Commun. Mater., 2023, DOI：10.1038/s43246-023-00395-y
  1. Exciton dynamics of a fused ring π-conjugated nonfullerene molecule based on dithienonaphthobisthiadiazole
    Y. Sato, T. Mikie, H. Yamada, I. Osaka, and H. Ohkita*
    Japanese Journal of Applied Physics, 2023, 62, SK1012
  1. Interplay Between π-Conjugated Polymer Donors and Acceptors Determines Crystalline Order of Their Blends and Photovoltaic Performance
    K. Yamanaka, M. Saito, T. Koganezawa, H. Saito, H.-D. Kim, H. Ohkita, and I. Osaka*
    Adv. Energy Mater. 2023, 13, 2203443
    Press release: 広島大学、京都大学、SPring-8
    News: 日本経済新聞、日本の研究 .com、マイナビニュース、オプトロニクス
  1. Naphthobispyrazine bisimide-based semiconducting polymers as electron acceptors for all-polymer photovoltaic cells
    K. Okamoto, Y. Iwasaki, T. Mikie*, and Itaru Osaka*
    Polymer J. 2023, 55, 443–450.

2022

  1. Halogen-Free π-Conjugated Polymers Based on Thienobenzobisthiazole for Efficient Nonfullerene Organic Solar Cells: Rational Design for Achieving High Backbone Order and High Solubility
    N. Nakao, M. Saito, T. Mikie, T. Ishikawa, J. Jeon, H.-D. Kim, H. Ohkita, A. Saeki, I. Osaka*
    Adv. Sci. 2022, 2205682.
  1. Ester-Functionalized Quinoxaline-Based Polymers for Application in Organic Photovoltaics
    T. Mikie*, Y. Iwasaki, and Itaru Osaka*
    Mater. Chem. Phys. 2022, 287, 126225.
  1. Naphthobisthiadiazole-Based π‑Conjugated Polymers for Nonfullerene Solar Cells: Suppressing Intermolecular Interaction Improves Photovoltaic Performance
    L-H. Chou, T. Mikie, M. Saito, C-L. Liu, and I. Osaka*
    ACS Appl. Mater. Interfaces 2022, 14, 12, 14400–14409.
  1. Naphthobispyrazine Bisimide: A Strong Acceptor Unit for Conjugated Polymers Enabling Highly Coplanar Backbone, Short π− π Stacking, and High Electron Transport
    T. Mikie, K. Okamoto, Y. Iwasaki, T. Koganezawa, M. Sumiya, T. Okamoto, and I. Osaka*
    Chem. Mater., 2022, 34, 2717–2729.
    Press release: 広島大学、東京大学、SPring-8
    News: 日本経済新聞、マイナビニュース、Mapionニュース、オプトロニクス

2021

  1. Pronounced Backbone Coplanarization by π-Extension in a Sterically Hindered Conjugated Polymer System Leads to Higher Photovoltaic Performance in Non-Fullerene Solar Cells
    N. Nakao, S. Ogawa, H. D. Kim, H. Ohkita, T. Mikie, M. Saito, and I. Osaka*
    ACS Appl. Mater. Interfaces 2021,13, 56420–56429.
  1. Extended π-Electron Delocalization in Quinoid-Based Conjugated Polymers Boosts Intrachain Charge Carrier Transport
    T. Mikie, M. Hayakawa, K. Okamoto, K. Iguchi, S. Yashiro, T. Koganezawa, M. Sumiya,  H. Ishii, S. Yamaguchi, A. Fukazawa*, and I. Osaka*
    Chem. Mater. 2021, 33, 8183–8193.
    Press release: 広島大学、京都大学、名古屋大学、東京大学、SPring-8
    News: 日本経済新聞、テクノロジーTECH+（マイナビニュース）、EE Times Japan
  1. Contrasting Effect of Side-Chain Placement on Photovoltaic Performance of Binary and Ternary Blend Organic Solar Cells in Benzodithiophene-Thiazolothiazole Polymers
    M. Saito, S. Ogawa, and I. Osaka*
    ChemSusChem, 2021, 14, 1−11
  1. Molecular Understanding of How the Interfacial Structure Impacts the Open-Circuit Voltage of Highly Crystalline Polymer Solar Cells
    T. Fukuhara, K. Yamazaki, T. Hidani, M. Saito, Y. Tamai, I. Osaka*, and H.Ohkita*
    ACS Appl. Mater. Interfaces 2021, 13, 34357−34366
  1. Effect of Ester Side Chains on Photovoltaic Performance in Thiophene-Thiazolothiazole Copolymers
    K. Yamanaka, M. Saito, T. Mikie, and I. Osaka*
    Bull. Chem. Soc. Jpn. 2021, 94, 2019–2027
  1. Self-powered ultraflexible photonic skin for continuous bio-signal detection via air-operation-stable polymer light-emitting diodes
    H. Jinno, T. Yokota, M. Koizumi, W. Yukita, M. Saito, I. Osaka, K. Fukuda, T. Someya
    Nat. Commun., 2021, 12, 7, 2234.
  1. Bithiazole Dicarboxylate Ester: An Easily Accessible Electron-Deficient Building Unit for π-Conjugated Polymers Enabling Electron Transport
    Y. Teshima, M. Saito, T. Mikie, K. Komeyama, and I. Osaka*
    Macromolecules 2021, 54, 7, 3489–3497
  1. Multi‐Channel Pumped Ultrasonic Spray‐Coating for High‐Throughput and Scalable Mixed Halide Perovskite Solar Cells
    A. Z. Guo, L. H. Chou, S. H. Yang, D. Wang, X. F. Wang, I. Osaka, H. W. Lin, C. L. Liu*
    Adv. Mater. Interfaces, 2021, 8, 2001509
  1. N-type Semiconducting Polymers Based on Dicyano Naphthobisthiadiazole: High Electron Mobility with Unfavorable Backbone Twist
    K. Iguchi, T. Mikie, M. Saito, K. Komeyama, T. Seo, Y. Ie*, and I. Osaka*
    Chem. Mater. 2021, 33, 2218−2228
  1. Spray deposition of NiOx hole transport layer and perovskite photoabsorber in fabrication of photovoltaic mini-module
    L. H. Chou, Y. T. Yu, I. Osaka, X. F. Wang, and C. L. Liu
    J. Power Sources 491 (2021) 229586.
  1. Donor−Acceptor Polymers Containing 4,8- Dithienylbenzo[1,2‐b:4,5‐b′]dithiophene via Highly Selective Direct Arylation Polymerization
    M. Wakioka*, N. Torii, M. Saito, I. Osaka, and F. Ozawa*
    ACS Appl. Polym. Mater. 2021, 3, 2, 830–836.
  1. Visible light-driven Giese reaction with alkyl tosylates catalysed by nucleophilic cobalt
    K. Komeyama,* T. Michiyuki, Y. Teshima, and I. Osaka
    RSC Adv., 2021,11, 3539-3546 DOI: 10.1039/D0RA10739E

2020

  1. Significantly Sensitized Ternary Blend Polymer Solar Cells with a Very Small Content of the Narrow-Band Gap Third Component That Utilizes Optical Interference
    M. Saito, Y. Tamai, H. Ichikawa, H. Yoshida, D. Yokoyama,* H. Ohkita,* and I. Osaka*
    Macromolecules 2020, 53, 10623−10635.
    Press release: Hiroshima University, Kyoto University, Chiba University, JST
  1. Controlled steric selectivity in molecular doping towards closest-packed supramolecular conductors
    S. Kohno, Y. Yamashita, N. Kasuya, T. Mikie, I. Osaka, K. Takimiya, J. Takeya, S. Watanabe*
    Communications Materials DOI: 10.1038/s43246-020-00081-3,
    Press release: Tokyo University, Hiroshima University.
  1. Impact of Noncovalent Sulfur–Fluorine Interaction Position on Properties, Structures, and Photovoltaic Performance in Naphthobisthiadiazole-Based Semiconducting Polymers
    M. Saito, T. Fukuhara, S. Kamimura, H. Ichikawa, H. Yoshida, T. Koganezawa, Y. Ie, Y. Tamai, H. D. Kim, H. Ohkita, I. Osaka
    Adv. Energy Mater. 2020, 10, 1903278.
  1. Effect of Spacer Length in Naphthobispyrazine-Based π-Conjugated Polymers on Properties, Thin Film Structures, and Photovoltaic Performances
    T. Mikie, Y. Teshima, K. Okamoto, I. Osaka
    Bull. Chem. Soc. Jpn.2020, 93, 949–957.
  1. Dithiazolylthienothiophene Bisimide-Based π-Conjugated Polymers: Improved Synthesis and Application to Organic Photovoltaics as P-Type Semiconductor
    Y. Teshima, M. Saito, T. Mikie, K. Komeyama, H. Yoshida, I. Osaka
    Bull. Chem. Soc. Jpn. 2020, 93, 561–567.
  1. Small-bandgap quinoid-based π-conjugated polymers
    T. Mikie, I. Osaka
    J. Mater. Chem. C, 2020, 8, 14262–14288.
    Selected as cover picture!!
  1. π-Conjugated polymers and molecules enabling small photon energy loss simultaneously with high efficiency in organic photovoltaics
    M. Saito, H. Ohkita, I. Osaka
    J. Mater. Chem. A, 2020, 8, 20213–20237.
    Selected as cover picture!!
  1. Reductive amidation of alkyl tosylates with isocyanates by a Ni/Co-dual catalytic system
    T. Michiyuki, I. Osaka, K. Komeyama
    Chem. Commun., 2020, 56, 1247—1250.
  1. Analyses of PTzNTz Polymer Solar Cells Using ESR Spectroscopy
    D. Xue, S. Kamiya, M. Saito, I. Osaka, K. Marumoto
    J. Photopolym. Sci. Technol., 2020, 33, 97-102.
  1. Mixed-Ligand Approach to Palladium-Catalyzed Direct Arylation Polymerization: Synthesis of Donor−Acceptor Polymers Containing Unsubstituted Bithiophene Units
    M. Wakioka, H. Morita, N. Ichihara, M. Saito, I. Osaka, F. Ozawa
    Macromolecules 2020, 53, 158−164.
  1. Semiconducting small molecule/polymer blends for organic transistors
    L-H. Chou, Y. Na, C-H. Park, M. S. Park, I. Osaka, F. S. Kim, C-L. Liu
    Polymer, 2020, 191, 122208.

2019

  1. Ester-Functionalized Naphthobispyrazine as an Acceptor Building Unit for Semiconducting Polymers: Synthesis, Properties, and Photovoltaic Performance
    T. Mikie, I. Osaka
    Macromolecules 2019, 52, 3909−3917.
  1. Dithiazolylthienothiophene Bisimide: A Novel Electron-Deficient　Building Unit for N‑Type Semiconducting Polymers
    Y. Teshima, M. Saito, T. Fukuhara, T. Mikie, K. Komeyama, H. Yoshida, H. Ohkita, I. Osaka
    ACS Appl. Mater. Interfaces 2019, 11, 23410−23416.
  1. Understanding Comparable Charge Transport Between Edge-on and Face-on Polymers in a Thiazolothiazole Polymer System
    M. Saito, T. Koganezawa, I. Osaka
    ACS Appl. Polym. Mater.2019, 1, 1257−1262.
  1. A Thiazolothiazole-Based Semiconducting Polymer withWell-Balanced Hole and Electron Mobilities
    M. Saito, I. Osaka
    Appl. Sci. 2019, 9, 451.
  1. Ni/Co-Catalyzed Homo-Coupling of Alkyl Tosylates
    K. Komeyama, R. Tsunemitsu, T. Michiyuki, H. Yoshida, I. Osaka
    Molecules, 2019, 24, 8.
  1. Nickel/Cobalt-Catalyzed C(sp3)−C(sp3) Cross-Coupling of Alkyl Halides with Alkyl Tosylates
    K. Komeyama, T. Michiyuki, I. Osaka
    ACS Catal. 2019, 9, 9285−9291.
  1. Durable Ultraflexible Organic Photovoltaics with Novel Metal-Oxide-Free Cathode
    Z. Jiang, K. Fukuda, W. Huang, S. Park, R. Nur, O. G.i Nayeem, K. Yu, D. Inoue, M. Saito, H. Kimura, T. Yokota, S. Umezu, D. Hashizume, I. Osaka, K. Takimiya, T. Someya
    Adv. Funct. Mater. 2019, 29, 1808378.
  1. Synthesis and Deformable Hierarchical Nanostructure of Intrinsically Stretchable ABA Triblock Copolymer Composed of Poly(3-hexylthiophene) and Polyisobutylene Segments
    T. Higashihara, S. Fukuta, Y. Ochiai, T. Sekine, K. Chino, T. Koganezawa, I. Osaka
    ACS Appl. Polym. Mater. 2019, 1, 315−320.
  1. Ultrasonic Spray-​Coated Mixed Cation Perovskite Films and Solar Cells
    Y-S. Chou, L-H. Chou, A-Z. Guo, X-F. Wang, I. Osaka, C-G. Wu, C-L. Liu
    ACS Sustainable Chem. Eng. 2019, 7, 14217−14224.
  1. High Operation Stability of Ultraflexible Organic Solar Cells with Ultraviolet‐Filtering Substrates
    H. Kimura, K. Fukuda, H. Jinno, S. Park, M. Saito, I. Osaka, K. Takimiya, S. Umezu, T. Someya
    Adv. Mater. 2019, 31, 1808033.

2018

  1. Correlation between Distribution of Polymer Orientation and Cell Structure in Organic Photovoltaics
    M. Saito, T. Koganezawa, I. Osaka
    ACS Appl. Mater. Interfaces 2018, 10, 32420−32425.
  1. Impact of side chain placement on thermal stability of solar cells in thiophene–thiazolothiazole polymers
    M. Saito, I. Osaka
    J. Mater. Chem. C, 2018, 6, 3668—3674.
  1. Selective Synthesis and Properties of Electron-Deficient HybridNaphthalene-Based π-Conjugated Systems
    T. Mikie, I. Osaka
    Chem. Eur.J. 2018, 24, 19228 –19235.
  1. Nickel and Nucleophilic Cobalt-Catalyzed Trideuteriomethylation of Aryl Halides Using Trideuteriomethyl p‑Toluenesulfonate
    K. Komeyama, Y. Yamahata, I. Osaka
    Org. Lett., 2018, 20, 4375−4378.
  1. Nickel-Catalyzed Reductive Bis-Allylation of Alkynes
    K. Komeyama, Y. Yamahata, I. Osaka
    Org. Lett., 2018, 20, 1457−1460.
  1. Three-component coupling of aryl iodides, allenes, and aldehydes catalyzed by a Co/Cr-hybrid catalyst
    K. Komeyama, S. Sakiyama, K. Iwashita, I. Osaka, K. Takaki
    Beilstein J. Org. Chem. 2018, 14, 1413–1420.
  1. Bimolecular recombination and fill factor in crystalline polymer solar cells
    T. Fukuhara, Y. Tamai, I. Osaka, H. Ohkita
    Jpn. J. Appl. Phys., 2018, 57, 853.
  1. Reverse-Offset Printed Ultrathin Ag Mesh for Robust Conformal Transparent Electrodes for High-Performance Organic Photovoltaics
    Z. Jiang, K. Fukuda, X. Xu, S. Park, D. Inoue, H. Jin, M. Saito, I. Osaka, K. Takimiya, T. Someya
    Adv. Mater. 2018, 30, 1707526.
  1. Scalable Ultrasonic Spray-Processing Technique for Manufacturing Large-Area CH3NH3PbI3 Perovskite Solar Cells
    L-H. Chou, X-F. Wang, I. Osaka, C-G. Wu, C-L. Liu
    ACS Appl. Mater. Interfaces 2018, 10, 38042−38050.

2017

  1. Naphthobischalcogenadiazole Conjugated Polymers: Emerging Materials for Organic Electronics
    I. Osaka, K. Takimiya
    Adv. Mater. 2017, 29, 1605218.
  1. Effects of branching position of alkyl side chains on ordering structure and charge transport property in thienothiophenedione- and quinacridone-based semiconducting polymers
    K. Kawabata, M. Saito, N. Takemura, I. Osaka, K. Takimiya
    Polym. J., 2017, 49, 169–176.
  1. Naphthobispyrazine as an Electron-deficient Building Unit for π-Conjugated Polymers: Efficient Synthesis and Polymer Properties
    T. Mikie, K. Kawashima, K. Komeyama, H. Yoshida, I. Osaka
    Chem. Lett., 2017, 46, 1193-1196.
  1. Synthesis and characterization of an alkoxythiazole-thiazolothiazole semiconducting polymer for organic solar cells
    M. Saito, I. Osaka
    Electrochemistry, 2017, 85, 266–271.
  1. Highly nucleophilic vitamin B12-assisted nickel-catalysed reductive coupling of aryl halides and non-activated alkyl tosylates
    K. Komeyama, R. Ohata, S. Kiguchi, I. Osaka
    Chem. Commun., 2017, 53, 6401–6404.
  1. Dithienyl Acenedithiophenediones as New π-Extended Quinoidal Core: Synthesis and Properties
    K. Kawabata, I. Osaka, M. Sawamoto, J. L. Zafra, P. M. Burrezo, J. Casado, K. Takimiya
    Chem. Eur. J, 2017, 23, 4579–4589.
  1. Exploring Alkyl Chains in Benzobisthiazole-Naphthobisthiadiazole Polymers: Impact on Solar-Cell Performance, Crystalline Structures, and Optoelectronics
    J. Tsutsumi, S. Matsuoka, I. Osaka, R. Kumai, T. Hasegawa
    ACS Appl. Mater. interfaces 2017, 9, 37702–37711. 
  1. Reduced exchange narrowing caused by gate-induced charge carriers in high-mobility donor-acceptor copolymers
    J. Tsutsumi, S. Matsuoka, I. Osaka, R. Kumai, T. Hasegawa
    Phys. Rev. B 2017, 95, 115306.
  1. Stretchable and waterproof elastomer-coated organic photovoltaics for washable electronic textile applications
    H. Jinno, K. Fukuda, X. Xu, S. Park, Y. Suzuki, M. Koizumi, T. Yokota, I. Osaka, K. Takimiya, T. Someya
    Nat. Energy 2017, 2, 780–785.

2016

  1. Dithienylthienothiophenebisimide, a Versatile Electron-Deficient Unit for Semiconducting Polymers
    M. Saito, I. Osaka, K. Takimiya, Y. Suda, H. Yoshida
    Adv. Mater. 2016, 28, 6921-6925.
  1. Implication of Fluorine Atom on Electronic Properties, Ordering Structures, and Photovoltaic Performance in Naphthobisthiadiazole-Based Semiconducting Polymers
    K. Kawashima, T. Fukuhara, Y. Suda, Y. Suzuki, T. Koganezawa, H. Yoshida, H. Ohkita, I. Osaka, K. Takimiya
    J. Am. Chem. Soc. 2016, 138, 10265–10275.
300
  1. Very Small Bandgap π-Conjugated Polymers with Extended Thienoquinoids
    K. Kawabata, M. Saito, I. Osaka, K. Takimiya
    J. Am. Chem. Soc. 2016, 138, 7725–7732.
  1. Amide-bridged terphenyl and dithienylbenzene units for semiconducting polymers
    M. Akita, M. Saito, I. Osaka, T. Koganezawa, K. Takimiya
    RSC Adv., 2016, 6, 16437–16447.
  1. Analyses of Thiophene-Based Donor-Acceptor Semiconducting Polymers toward Designing Optical and Conductive Properties: A Theoretical Perspective
    T. Matsui, Y. Imamura, I. Osaka, K. Takimiya, T. Nakajima
    J. Phys. Chem. C 2016, 120, 8305–8314.

2015

  1. Backbone orientation in semiconducting polymers
    I. Osaka, K. Takimiya
    Polymer 2015, 59, A1–A15.
  1. Effect of Chalcogen Atom on the Properties of Naphthobischalcogenadiazole-Based π-Conjugated Polymers
    K. Kawashima, I. Osaka, K. Takimiya
    Chem. Mater. 2015, 27, 6558–6570.
  1. Efficient inverted polymer solar cells employing favourable molecular orientation
    V. Vohra, K. Kawashima, T. Kakara, T. Koganezawa, I. Osaka, K. Takimiya, H. Murata
    Nat. Photon. 2015, 9, 403–408.
  1. High-efficiency polymer solar cells with small photon energy loss
    K. Kawashima, Y. Tamai, H. Ohkita, I. Osaka, K. Takimiya
    Nat. Commun., 2015, 6, 10085.
  1. Highly Efficient and Stable Solar Cells Based on Thiazolothiazole and Naphthobisthiadiazole Copolymers
    S. Masahiko, I. Osaka, Y. Suzuki, K. Takimiya, T. Okabe, S. Ikeda, T. Asano.
    Sci Rep. 2015, 5, 14202.
  1. Thienothiophene-2,5-dione-based donor-acceptor polymers: Improved synthesis and influence of the donor units on ambipolar charge transport properties
    Kawabata Kohsuke, Osaka Itaru, Nakano Masahiro, Takemura Noriko, Koganezawa Tomoyuki, Takimiya Kazuo
    Adv. Electron. Mater., 2015, 1, 1500039.
  1. On the role of local charge carrier mobility in the charge separation mechanism of organic photovoltaics
    S. Yoshikawa, A. Saeki, M. Saito, I. Osaka, S. Seki
    Phys. Chem. Chem. Phys., 2015, 17, 17778–17784.
  1. Semiconducting polymers based on electron-deficient π-building units
    I. Osaka
    Polymer Journal 2015, 47, 18–25.
  1. Angular-Shaped 4,9-Dialkyl α- and β-Naphthodithiophene-Based Donor-Acceptor Copolymers: Investigation of Isomeric Structural Effects on Molecular Properties and Performance of Field-Effect Transistors and Photovoltaics
    S-W. Cheng, D-Y. Chiou, C-E. Tsai, W-W. Liang, Y-Y. Lai, J-Y. Hsu, C-S. Hsu, I. Osaka, K. Takimiya, Y-J. Cheng
    Adv. Funct. Mater., 2015, 25, 6131–6143.

2014

  1. Thiophene-​thiazolothiazole copolymers: significant impact of side chain composition on backbone orientation and solar cell performances
    I. Osaka, M. Saito, T. Koganezawa, K. Takimiya
    Adv. Mater., 2014, 26, 331–338.
  1. Small band gap polymers incorporating a strong acceptor, thieno[3,​2-​b]​thiophene-​2,​5-​dione, with p-​channel and ambipolar charge transport characteristics
    I. Osaka, T. Abe, H. Mori, M. Saito, N. Takemura, T. Koganezawad, K. Takimiya
    J. Mater. Chem. C, 2014, 2, 2307–2312.
  1. Effect of Oxygen-​Containing Functional Side Chains on the Electronic Properties and Photovoltaic Performances in a Thiophene-​Thiazolothiazole Copolymer System
    M. Saito, I. Osaka, T. Koganezawa, K. Takimiya
    Heteroat. Chem., 2014, 25, 556–564.
  1. Contrasting Effect of Alkylation on the Ordering Structure in Isomeric Naphthodithiophene-​Based Polymers
    I. Osaka, Y. Houchin, M. Yamashita, T. Kakara, N. Takemura, T. Koganezawa, K. Takimiya
    Macromolecules 2014, 47, 10, 3502–3510.
  1. Achieving high efficiency and stability in inverted organic solar cells fabricated by laminated gold leaf as top electrodes
    N. T. Razali, I. Osaka, K. Takimiya, V. Vohra, H. Murata
    Appl. Phys. Express., 2014, 7, 111602.
  1. 5,​10-​Linked naphthodithiophenes as the building block for semiconducting polymers
    I. Osaka, K. Komatsu, T. Koganezawa, K. Takimiya
    Sci. Technol. Adv. Mater., 2014, 15, 024201.
  1. π-​Building Blocks for Organic Electronics: Revaluation of “Inductive” and “Resonance” Effects of π-​Electron Deficient Units
    K. Takimiya, I. Osaka, M. Nakano
    Chem. Mater.,2014, 26, 1, 587–593.
  1. Highly oriented polymer semiconductor films compressed at the surface of ionic liquids for high-​performance polymeric organic field-​effect transistors
    J. Soeda, H. Matsui, T. Okamoto, I. Osaka, K. Takimiya, J. Takeya
    Adv. Mater., 2014, 26, 6430–6435.
  1. Thiazolothiazole-​based polymers for organic solar cells
    I. Osaka, M. Saito, K. Takimiya
    Journal of the Imaging Society of Japan, 2014, 53, 523–528.
  1. Crystalline conjugated polymers for organic electronics
    I. Osaka, K. Takimiya
    Mater. Sci. Eng., 2014, 54, 012016.

2013

  1. Quinacridone-​diketopyrrolopyrrole-​based polymers for organic field-​effect transistors
    M. Akita, I. Osaka, K. Takimiya
    Materials 2013, 6, 1061–1071.
  1. Naphthodithiophenes as building units for small molecules to polymers; a case study for in-​depth understanding of structure-​property relationships in organic semiconductors
    I. Osaka, S. Shinamura, T. Abe, K. Takimiya
    J. Mater. Chem. C, 2013, 1, 1297–1304.
  1. Naphthodithiophene-​naphthobisthiadiazole copolymers for solar cells: alkylation drives the polymer backbone flat and promotes efficiency
    I. Osaka, T. Kakara, N. Takemura, T. Koganezawa, K. Takimiya
    J. Am. Chem. Soc., 2013, 135, 24, 8834–8837.
  1. 5,​10-​Diborylated naphtho[1,​2-​c:5,​6-​c’]​bis[1,​2,​5]​thiadiazole: a ready-​to-​use precursor for the synthesis of high-​performance semiconducting polymers
    K. Kawashima, E. Miyazaki, M. Shimawaki, Y. Inoue, H. Mori, N. Takemura, I. Osaka, K. Takimiya
    Polym. Chem., 2013, 4, 5224–5227.

2012

  1. Synthesis, Characterization, and Transistor and Solar Cell Applications of a Naphthobisthiadiazole-Based Semiconducting Polymer
    I. Osaka, M. Shimawaki, H. Mori, I. Doi, E. Miyazaki, T. Koganezawa, K. Takimiya
    J. Am. Chem. Soc., 2012, 134, 3498–3507.
  1. Quinacridone-​Based Semiconducting Polymers: Implication of Electronic Structure and Orientational Order for Charge Transport Property
    I. Osaka, M. Akita, T. Koganezawa, K. Takimiya
    Chem. Mater., 2012, 24, 1235–1243.
  1. Naphthodithiophene-​Based Donor-​Acceptor Polymers: Versatile Semiconductors for OFETs and OPVs
    I. Osaka, T. Abe, M. Shimawaki, T. Koganezawa, K. Takimiya
    ACS Macro Lett., 2012, 1, 4, 437–440.
  1. Drastic change of molecular orientation in thiazolothiazole copolymers by molecular weight control and blending with PC61BM leads to high efficiencies in solar cells
    I. Osaka, M. Saito, H. Mori, T. Koganezawa, K. Takimiya
    Adv. Mater., 2012, 24, 425–430.

2011

  1. Impact of isomeric structures on transistor performances in naphthodithiophene semiconducting polymers
    I. Osaka, T. Abe, S. Shinamura, K. Takimiya
    J. Am. Chem. Soc., 2011, 133, 6852–6860.
  1. Mixed selenium-sulfur fused ring systems as building blocks for novel polymers used in field effect transistors
    S. P. Mishra, A. E. Javier, R. Zhang, J. Liu, J. A. Belot, I. Osaka, R. D. McCullough
    J. Mater. Chem., 2011, 21, 1551–1561.
  1. Insight into how molecular structures of thiophene-based conjugated polymers affect crystallization behaviors
    J. Liu, I. A. Mikhaylov, J. Zou, I. Osaka, A. E. Masunov, R. D. McCullough, L. Zhai
    Polymer 2011, 52, 2302–2309.
  1. Donor-acceptor semiconducting polymer based on thiazole-containing fused-rings for organic field-effect transistors
    I. Osaka, K. Takimiya, R. D. Mccullough
    Kobunshi Ronbunshu, 2011, 68, 1–10.

2010

  1. Highly Stable Semiconducting Polymers Based on Thiazolothiazole
    I. Osaka, R. Zhang, J. Liu, D-M. Smilgies, T. Kowalewski, R. D. McCullough
    Chem. Mater., 2010, 22, 4191–4196.
  1. High-mobility semiconducting naphthodithiophene copolymers
    I. Osaka, T. Abe, S. Shinamura, E. Miyazaki, K. Takimiya
    J. Am. Chem. Soc., 2010, 132, 5000–5001.
  1. Benzobisthiazole-based semiconducting copolymers showing excellent environmental stability in high-humidity air
    I. Osaka, K. Takimiya, R. D. McCullough
    Adv. Mater., 2010, 22, 4993–4997.
  1. Regioregular and Regiosymmetric Polythiophenes
    I. Osaka, R. D. McCullough
    Conjugated Polymer Synthsis, 2010, 15, 59–90.
  1. Advanced functional regioregular polythiophenes.
    I. Osaka, R. D. McCullough
    Design and Synthesis of Conjugated Polymers 2010, 19, 91–145.

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