Isobe, Tetsuhiko

写真a

Affiliation

Faculty of Science and Technology, Department of Applied Chemistry (Yagami)

Position

Professor

Related Websites

External Links
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Profile Summary 【 Display / hide 】

  • 私たちの研究室では、ユニークな液相合成法を活用して０次元や２次元の形態を有するナノ蛍光体材料を開発しています。たとえば、ディスプレイの広色域化を可能にするペロブスカイト量子ドット、太陽電池応用を指向した近紫外線を赤色や近赤外線に波長変換するナノシート、低毒性・環境親和性を有するカーボンドット、近紫外線照射で可視光を発する銀イオン交換ゼオライトナノ粒子などを研究しています。

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Career 【 Display / hide 】

  • 1989.04
    -
    1995.03

    Keio University, Assistant

  • 1993.09
    -
    1994.08

    Vanderbilt University (USA), Visiting scholar

  • 1995.04
    -
    1999.03

    Keio University, Assistant Professor

  • 1999.04
    -
    2007.03

    Keio University, Associate Professor

  • 1999.09
    -
    2000.08

    École Supérieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI)(France), Visiting scholar

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Academic Background 【 Display / hide 】

  • 1986.03

    Keio University, Faculty of Science and Engineering, 応用化学科

    University, Graduated

  • 1988.03

    Keio University, Graduate School, Division of Science and Engineeri, 応用化学専攻

    Graduate School, Completed, Master's course

  • 1991.03

    Keio University, Graduate School, Division of Science and Engineeri, 応用化学専攻

    Graduate School, Withdrawal after completion of doctoral course requirements, Doctoral course

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Academic Degrees 【 Display / hide 】

  • Doctor (Engineering), Keio University, Coursework, 1992.02

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Research Areas 【 Display / hide 】

  • Nanotechnology/Materials / Inorganic materials and properties

  • Nanotechnology/Materials / Nanobioscience (Nano Materials/Nano Bioscience)

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Research Keywords 【 Display / hide 】

  • Phosphors

  • Nanophosphor

  • Quantum dots

  • Luminescent nanomaterials

  • Nanocomposite materials

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Books 【 Display / hide 】

  • 次世代ディスプレイへの応用に向けた材料、プロセス技術の開発動向

    磯　由樹, 磯部　徹彦, 技術情報協会, 2020.02

    Scope: 第８章 第４節 完全無機ペロブスカイトナノ結晶蛍光体の特性、合成法および耐久性の改善

  • 量子ドット材料の技術と応用展開：　ディスプレイ・照明・バイオ応用から太陽電池まで

    磯 由樹, 磯部　徹彦, 情報機構, 2017.06

    Scope: 第４章第２節　ペロブスカイト型量子ドット蛍光体

  • 次世代蛍光体材料の開発

    磯 由樹, 磯部　徹彦, シーエムシー出版, 2016.07

    Scope: 第４編 第１章 CdフリーCuInS2量子ドット，第２章 ドープ型量子ドット，第３章 ナノシート蛍光体

  • ナノ粒子の表面修飾と分析評価技術～各種特性を向上するためのナノ粒子表面関連技術とその評価～

    磯部　徹彦, 情報機構, 2016.01

    Scope: 第４章　第6節　蛍光ナノ粒子の表面修飾

  • 近赤外・紫外線-波長変換と光吸収増大による太陽電池の高効率化技術

    磯 由樹, 磯部　徹彦, S&T出版, 2016.01

    Scope: 第1章　第1節　ナノ蛍光体による近紫外線→可視光・近赤外線変換と結晶シリコン太陽電池への応用

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Papers 【 Display / hide 】

  • Implications for applicability of the photodegradation and self-recovery of green-emitting CsPbBr<inf>3</inf> perovskite nanocrystals

    Iso Y., Saito S., Toyoda H., Isobe T.

    RSC Advances 14 ( 36 ) 26059 - 26065 2024.08

    Joint Work

    　View Summary

    CsPbBr3 nanocrystals (NCs) synthesized by the conventional hot-injection method are photochromatic luminescent nanomaterials due to the photoinduced desorption and re-adsorption of the surface ligands. The apparent color and the luminescence intensity were changed significantly during excitation light irradiation and following dark storage; however, the emission wavelength was almost retained. This work investigates the change in emission color of light-emitting diode lighting using the CsPbBr3 NCs to realize photochromatic luminescence. The results showed definite shifts in emission color caused by changes in optical absorption and green luminescence intensity of the NCs, potentially broadening the application feasibility of CsPbBr3 NCs as photochromatic luminescent nanomaterials.

  • Open system massive synthesis of narrow-band blue and green fluorescent graphene quantum dots and their application in water sensing

    Ochi Y., Otani A., Katakami R., Ogura A., Takao K.I., Iso Y., Isobe T.

    Journal of Materials Chemistry C (Journal of Materials Chemistry C)  12 ( 18 ) 6548 - 6558 2024.04

    Joint Work, Accepted,  ISSN  20507526

    　View Summary

    Graphene quantum dots (GQDs) are environmentally friendly fluorescent carbon-based nanomaterials. However, there is no report on the massive synthesis of GQDs with narrow-band fluorescence and a high photoluminescence quantum yield (PLQY) using a simple liquid-phase method under atmospheric conditions. In this study, GQDs were successfully synthesized in ∼100% product yield by heating phloroglucinol (PG) with Na3PO4·12H2O in 1,2-pentanediol at 180 °C for 6 h in an open system with air flow, followed by dialysis purification. The high product yield was attributed to the addition of Na3PO4·12H2O as a base catalyst, which promoted the dehydration-condensation reaction between PG molecules. The dispersion of PG derived GQDs (PG-GQDs) in ethanol resulted in blue fluorescence with a full width at half maximum of 32 nm and a PLQY of 54%. Further purification of PG-GQDs by silica gel column chromatography improved the PLQY to 75%. Fourier-transform infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, and X-ray photoelectron spectroscopy confirmed that dehydration-condensation reactions occurred not only between PGs but also between GQDs and 1,2-pentanediol. The binding of 1,2-pentanediol to the edges of GQDs suppressed the stacking of GQDs and prevented concentration quenching, resulting in a high PLQY. PG-GQDs exhibited negative fluorescence solvatochromism, i.e., the fluorescence wavelength blue-shifted with increasing solvent polarity. Dispersion of PG-GQDs in N-methyl-2-pyrrolidone (MP) resulted in green fluorescence with a PLQY of 96%. Dispersion of PG-GQDs in water resulted in blue fluorescence and a low PLQY of 6% at pH 7, while the PLQY was more than 50% at pH ≥ 11. Using these properties, the sensing of water (pH 13) in MP was investigated. The results showed that as the water content was increased from 0% to 100%, the fluorescence color gradually changed from green to blue and the fluorescence wavelength continuously shifted from 514 nm to 466 nm, indicating their applicability in water sensing.

  • Eco-Friendly Electrophoretic Deposition of Fluorescent Nanocomposite Films in an Aqueous Dispersion of Hydrophilized Core/Shell CuInS2/ZnS Quantum Dots for Optoelectronic Applications

    Morimoto A., Iso Y., Isobe T.

    ACS Applied Materials & Interfaces (ACS Applied Materials and Interfaces)  16 ( 6 ) 7780 - 7789 2024.02

    Research paper (scientific journal), Joint Work, Accepted,  ISSN  19448244

    　View Summary

    Low-toxic and efficient fluorescent core-shell CuInS2/ZnS (CIS/ZnS) quantum dots (QDs) are good candidates for optoelectronic device applications. They are synthesized in a hydrophobic environment, while large amounts of organic solvents used in the preparation of fluorescent films have significant problems on environmental load and human health. CIS/ZnS QDs hydrophilized by adsorbing 3-mercaptopropionic acid on their surfaces can be used in the aqueous film fabrication process. In this work, the aqueous electrophoretic deposition (EPD) of the hydrophilized QDs with silicone-modified acrylic resin nanoparticles was performed to fabricate fluorescent nanocomposite films. The hydrophilized QDs and resin nanoparticles were simultaneously dispersed in basic aqueous solutions due to electrostatic repulsion resulting from their negatively charged surfaces. Transparent films were obtained on a transparent conductive substrate at the anode side by the EPD. They showed yellow fluorescence of the QDs. The thickness increased with increasing the deposition time; however, hemispherical holes attributed to oxygen gas generated by water electrolysis were observed at the longer time. The electron microscopy revealed that the films were densely and homogeneously deposited. The QDs were dispersed around the resin nanoparticles without aggregation. The fluorescence (FL) quantum yield was 43%. The optical absorption peak and FL intensity of the QDs increased accompanied by the film growth. The nanocomposite film showed good heat resistance at 80-120 °C for 5 h; therefore, the prepared films have feasibility in white light-emitting diode (LED) applications. A lightening device structured with the obtained EPD film placed on a blue LED successfully emitted white light. In addition, the flexibility of the nanocomposite film was demonstrated. The aqueous EPD method would be one of the suitable methods for the industrial production of fluorescent QD films. This technique can be applied to other hydrophilic fluorescent QDs with charged surfaces. Realization of various fluorescent QD films would expand the application possibilities.

  • Improved photoluminescence of di, tri, and tetra-aminobenzene molecules hydrogen-bonded by polyethyleneimine and their application for metal ion sensing

    Tan H., Iso Y., Isobe T.

    Journal of Luminescence (Journal of Luminescence)  266 2024.02

    Joint Work,  ISSN  00222313

    　View Summary

    Higher photoluminescence quantum yield (PLQY) is always a required property for fluorescent molecule dyes used as probes in aqueous environment because of non-radiative relaxation via O–H vibrations. 1,2,4-triaminobenzene (TriAB) dihydrochloride has been reported as a red-emitting fluorescent dye, although its photoluminescence (PL) intensity is very low. Here, a bright orange-emitting fluorophore was prepared by simply mixing TriAB and polyethyleneimine (PEI) in water at pH 7 and applied to metal ion sensing. The PLQY was increased from 3.1 % to 10.0 % by the addition of PEI into an aqueous TriAB solution. Our experiments by exchanging H2O for D2O and changing the pH from 7 to 1 revealed that the role of PEI in enhancing the PL intensity is attributed to the interaction between the amino groups of TriAB and PEI via hydrogen bonding, the prevention of contact between TriAB and water molecules, and thus the suppression of the non-radiative relaxation via O–H vibrations of H2O. We further demonstrated this role for 1,4-diaminobenzene and 1,2,4,5-tetraaminobenzene.

  • Assembly-promoted repeatable enhancement of photoluminescence from cesium lead tribromide nanocubes under light illumination

    Hashimoto S., Watanabe H., Iso Y., Oaki Y., Isobe T., Imai H.

    Nanoscale Advances 6 ( 22 ) 5563 - 5567 2024

    Joint Work,  ISSN  2516-0230

    　View Summary

    A repeatable enhancement of the photoluminescence (PL) from CsPbBr3 nanocubes (NCs) is promoted by the assembling of NCs. The PL quantum yield (QY) of ordered NC arrays increases with photoirradiation and decreases in the dark. The repeatable enhancement of the PLQY cannot be observed from isolated NCs. The nanospaces between NCs in the ordered arrays allow a reversible change in thermally stimulated desorption and photo-induced adsorption of surface ligands that affect the PLQY.

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Papers, etc., Registered in KOARA 【 Display / hide 】

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Reviews, Commentaries, etc. 【 Display / hide 】

  • (Invited, Digital Presentation) Surface Engineering of Fluorescent CsPbBr3 and Carbon Quantum Dots By Perfluorocarboxylic Acid

    ECS Meeting Abstracts  2022.10

    Joint Work

  • 単結晶シリコン太陽電池の波長変換材料を目指した量子ドットの開発

    磯　由樹，磯部　徹彦

    機能材料 (シーエムシー出版)  41 ( 4 ) 19 - 27 2021.04

    Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media), Joint Work

  • 新しい蛍光体材料カーボンドットとは？─緑色や赤色に発光するナノ炭素材料

    磯　由樹，磯部　徹彦

    化学 (化学同人)  76 ( 3 ) 68 - 69 2021.03

    Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media), Joint Work

  • ナノ蛍光体：発光する半導体量子ドット

    磯　由樹，磯部　徹彦

    粉体工学会誌 57 ( 12 ) 641 - 646 2020.12

    Article, review, commentary, editorial, etc. (scientific journal), Joint Work

  • 新たなナノ蛍光体の台頭─ペロブスカイトナノ結晶とカーボンドット─

    磯　由樹，磯部　徹彦

    セラミックス 55 ( 11 ) 796 - 799 2020.11

    Article, review, commentary, editorial, etc. (scientific journal), Joint Work

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Presentations 【 Display / hide 】

  • 量子ドット蛍光体の基礎と新展開

    磯部　徹彦

    新化学技術推進協会　電子情報技術部会　ナノフォトニクスエレクトロニクス交流会講演会 (オンライン) , 

    2024.04
    , 

    Oral presentation (invited, special)

  • 量子ドット蛍光体の紹介と取り組みー分散と安定性を中心にしてー

    磯部　徹彦

    有機エレクトロニクス材料研究会 第259回研究会 (オンライン) , 

    2024.02
    , 

    Oral presentation (invited, special)

  • 太陽電池応用のための量子ドット蛍光体フィルムの開発

    磯　由樹，磯部　徹彦

    応用物理学会応用電子物性分科会 2023年11月研究例会 (オンライン) , 

    2023.11
    , 

    Oral presentation (invited, special)

  • Improved Photoluminescence of Tri-Aminobenzene Molecules Modified by Polyethyleneimine and Their Application for Metal Ion Sensing

    Haowei Tan, Yoshiki Iso, Tetsuhiko Isobe

    第13回CSJ化学フェスタ2023 (タワーホール船堀，東京) , 

    2023.10
    , 

    Poster presentation

  • CuInS2/ZnS量子ドットを用いた発光型太陽集光装置の構築と発電特性

    今給黎　祐，磯　由樹，磯部　徹彦

    第13回CSJ化学フェスタ2023 (タワーホール船堀，東京) , 

    2023.10
    , 

    Poster presentation

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

  • Pioneering Liquid Phase Synthesis of Innovative Carbon Quantum Dot Fluorescent Materials

    2024.04
    -
    2027.03

    Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), Research grant, No Setting

    　View Summary

    蛍光ピークが単一であり、蛍光ピーク幅が狭く、蛍光ピーク波長が調節可能である蛍光特性を持ち合わせた、環境負荷の少ない炭素を主成分とするカーボン量子ドット（CQD）蛍光材料を作製することを追究する。研究代表者のグループのこれまでの無機化合物量子ドットの液相合成での知見と技術を活かして、高沸点の非水溶媒を使用し、電子供与性官能基をもつ炭素原料分子をビルディングブロックとして組み立てる液相合成法を構築する。sp2ドメインを形成し、HOMO－LUMO間のπ電子遷移により励起・蛍光を起こさせ、周囲環境の極性により励起・蛍光エネルギーを制御できる革新的CQD蛍光材料を開拓する。

  • Development of advanced liquid-phase synthesis of carbon dots with controlled photoluminescence properties

    2019.06
    -
    2022.03

    Keio University, Grants-in-Aid for Scientific Research, Isobe Tetsuhiko, Challenging Research (Exploratory), Research grant, Principal investigator

    　View Summary

    Recently, quantum dots (QDs), which emit light in the band gap and whose emission color can be tuned by controlling particle size through the quantum size effect, have emerged. CdSe, InP, and CsPbBr3 have been developed as QD materials; however, they have problems in terms of toxicity and stability. Against this background, light-emitting materials with high environmental friendliness are required; therefore, we focused on the preparation of luminescent carbon dots (CDs) from abundant carbon sources. In this work, we pioneered an advanced liquid-phase method to synthesize CDs by polymerizing aromatic compound materials in non-aqueous solvents. Furthermore, the effects of surface modification and surrounding environment on the luminescence properties were investigated to control them.

  • Improvement of properties of solar cells by quantum dots with the function of UV - visible wavelength conversion

    2018.04
    -
    2021.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, ISOBE Tetsuhiko, Grant-in-Aid for Scientific Research (B), Research grant, Principal investigator

    　View Summary

    An ultraviolet light absorber is used in a photovoltaic module to protect its parts from ultraviolet light. As a result, in photovoltaic modules, the spectral sensitivity of wavelengths below 400 nm is reduced. If a phosphor converting ultraviolet light into visible light is used instead of the ultraviolet light absorber, it is possible to protect the photovoltaic module from ultraviolet light and at the same time to improve the spectral sensitivity of the photovoltaic module in ultraviolet range. In this research, we have developed core / shell type CuInS2/ZnS and CuGaS2/ZnS quantum dot phosphors that convert ultraviolet light to visible light and have high transparency to visible light with high spectral sensitivity of photovoltaic modules. We investigated the improvement of photoelectric conversion efficiency of the photovoltaic module by wavelength conversion of these quantum dots.

  • Preparation, characterization, and application of near-UV -> red conversion fluorescent nanosheets and their composite films

    2015.04
    -
    2018.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, ISOBE Tetsuhiko, Grant-in-Aid for Scientific Research (C), Research grant, Principal investigator

    　View Summary

    Y2O3:Bi3+,Eu3+ nanosheets, which emit red light under near-UV irradiation, were obtained by calcining hydroxide precursor nanosheets synthesized through a hydrothermal method. An aqueous dispersion of positively charged Y2O3:Bi3+,Eu3+ nanosheets with polyethyleneimine adsorbed to the surface was prepared for their deposition. Fluorescent nanosheets were electrophoretically deposited on a transparent conductive substrate under a constant voltage. Next, polyvinylpyrrolidone was coated on the film. The effects of the PVP-coated film samples on the properties of a commercial monocrystalline silicon photovoltaic module were evaluated.

  • Preparation and characterization of biocompatible composite beads with fluorescent nanoparticles

    2011.04
    -
    2014.03

    Keio University, ISOBE Tetsuhiko, Grant-in-Aid for Scientific Research (B), Research grant, Principal investigator

    　View Summary

    Preparation of chitosan beads by cross-linking method through electrostatic interaction with tripolyphosphate ions, combined with emulsification method using SPG membrane was studied. Next, hybridizations between green-emitting YAG:Ce3+ nanoparticles and chitosan beads, and between red-emitting Eu3+-doped apatite nanoparticles and chitosan beads were studied. Hybridizations between Eu3+-doped apatite nanoparticles and silica beads, and between YAG:Ce3+ nanoparticles and alginate beads were also studied.

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Works 【 Display / hide 】

  • 技術情報協会Live配信セミナー「～２０２３年「ノーベル化学賞」受賞テーマ～「量子ドット(ＱＤ)」の設計，カドミウムフリー化，応用，今後の展望」：「量子ドット蛍光体の基礎・分散性・安定性」

    磯部　徹彦

    オンライン, 

    2024.03
    , 

    Other, Single

  • 早慶交換講義「無機ナノ蛍光体の研究開発への挑戦」

    ISOBE TETSUHIKO

    2013.04
    , 

    Other, Single

  • 慶應義塾大学メディアセンターMediaNet, No.18, p.25, ティールーム「電子化でちょっと気になること」

    ISOBE TETSUHIKO

    2011.11
    , 

    Other, Single

  • ソニーケミカル＆インフォメーションデバイス株式会社　鹿沼事業所における講演　「ドープ型ナノ蛍光体に関する研究動向と展望」

    ISOBE TETSUHIKO

    2011.09
    , 

    Other, Single

  • 関東学院六浦高等学校　模擬授業　「身近で活躍する発光材料」

    磯部 徹彦

    2011.06
    , 

    Other, Single

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Intellectual Property Rights, etc. 【 Display / hide 】

  • 発光体の製造方法

    Date applied： 特願平9-212171  1997.08 

    Date announced： 特開平10-310770  1998.11 

    Patent

  • 発光体の製造方法

    Date applied： 特願平10-273596  1998.09 

    Date announced： 特開2000-104058  2000.04 

    Patent

  • ハイドロキシアパタイトの合成方法，ハイドロキシアパタイト複合体およびその製造方法

    Date applied： 特願2000-607922  1999.03 

    Date announced： WO00/58209  2000.10 

    Patent

  • リン酸カルシウム粉体の製造方法

    Date applied： 特願2000-607923  1999.03 

    Date announced： WO00/58210  2000.10 

    Patent

  • はんだ粉末とその製造方法、およびソルダーペースト

    Date applied： 特願平11-187637  1999.07 

    Date announced： 特開2000-317682  2000.11 

    Patent

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Awards 【 Display / hide 】

  • Outstanding Poster Paper Award

    T. Watanabe, Y. Iso, T. Isobe, H. Sasaki, 2017.12, The 24th International Display Workshops（IDW'17), Improved Photostability of Tetramethyl Orthosilicate-Modified InP/ZnS Quantum Dots

    Type of Award： Award from international society, conference, symposium, etc.

  • The Poster Award

    Kenji Akisada, Yusuke Noguchi, Tetsuhiko Isobe, 2010.11, The 3rd International Congress on Ceramics (ICC3) Symposim 5 "Hybrid and Nano-Structured Materials", Preparation of composite PMMA microbeads hybridized with fluorescent YVO4:Bi3+,Eu3+

    Type of Award： Award from international society, conference, symposium, etc.

  • Best Paper Award

    Wakana Kichikawa, Fumiaki Nishimura, Tetsuhiko Isobe, 2006.09, The International Union Materials Research Society － International Conference in Asia 2006　（IUMRS－ICA　2006）, Photoluminescence of the Highly Transparent Colloidal Solution of LaPO4:Ce3+, Tb3+ Nanocrystal Phosphors Synthesized by Low-Temperature Solvothermal Method : Effect of Polyphosphate Additive

    Type of Award： Award from international society, conference, symposium, etc.

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Courses Taught 【 Display / hide 】

  • SEMINAR IN APPLIED CHEMISTRY

    2024

  • NANO SCALE SCIENCE JOINT SEMINAR

    2024

  • MATERIAL DESIGN SCIENCE JOINT SEMINAR

    2024

  • LABORATORIES IN APPLIED CHEMISTRY A

    2024

  • INTRODUCTION OF MATERIAL DESIGN 2

    2024

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Courses Previously Taught 【 Display / hide 】

  • 固体の機能設計

    慶應義塾大学大学院

    2018.04
    -
    2019.03

  • 機能デザイン工学

    慶應義塾大学大学院

    2018.04
    -
    2019.03

  • 総合デザイン工学特別研究第１

    慶應義塾大学大学院

    2018.04
    -
    2019.03

  • 総合デザイン工学課題研究

    慶應義塾大学大学院

    2018.04
    -
    2019.03

  • 総合デザイン工学特別研究第２

    慶應義塾大学大学院

    2018.04
    -
    2019.03

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Memberships in Academic Societies 【 Display / hide 】

  • 電気化学会 蛍光体研究懇談会（蛍光体同学会）, 

    2001.01
    -
    Present

  • 応用物理学会, 

    1996.02
    -
    Present

  • 電気化学会, 

    2011.01
    -
    Present

  • 日本セラミックス協会, 

    2011.04
    -
    Present

  • Electrochemical Society, 

    2008.10
    -
    Present

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Committee Experiences 【 Display / hide 】

  • 2022.01
    -
    Present

    会長, 電気化学会 蛍光体研究懇談会（蛍光体同学会）

  • 2007.01
    -
    Present

    幹事, 電気化学会 蛍光体研究懇談会（蛍光体同学会）

  • 2014.04
    -
    Present

    代議員, 電気化学会

  • 2017.10
    -
    Present

    Luminescence and Display Materials Division, Executive Committee Member-at-Large, Electrochemical Society

  • 2004.06
    -
    2023.12

    委員, 日本学術振興会　光電相互変換第125委員会

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