Details of a Researcher - Isobe, Tetsuhiko

Isobe, Tetsuhiko

写真a

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

Position: Professor

Related Websites

研究室紹介ＨＰ

External Links

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。

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

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

Academic Degrees 【 Display / hide 】

Doctor (Engineering), Keio University, Coursework, 1992.02

Research Areas 【 Display / hide 】

Nanotechnology/Materials / Inorganic materials and properties
Nanotechnology/Materials / Nanobioscience (Nano Materials/Nano Bioscience)

Research Keywords 【 Display / hide 】

Phosphors
Nanophosphor
Quantum dots
Luminescent nanomaterials
Nanocomposite materials

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

Papers 【 Display / hide 】

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.
- Access to Document (DOI)
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.
- Access to Document (DOI)
Surface Modification Strategy for Yellow-Emitting Carbon Dots in Fluoropolymer Films

Washio K., Sato K., Iso Y., Isobe T.

ECS Journal of Solid State Science and Technology （ECS Journal of Solid State Science and Technology) 12 （ 7 ） 2023.07

Joint Work, ISSN 21628769

　View Summary

Carbon dots (CDs) were prepared from p-phenylenediamine, modified with trifluoroacetic acid, and dispersed in a fluoropolymer (FP) film. Unmodified CDs did not disperse well in the FP film, resulting in concentration quenching; whereas surface modification improved the affinity between the CDs and the FP, resulting in a homogeneous dispersion and an improved photoluminescence quantum yield.
- Access to Document (DOI)
Effects of Perfluorodecanoic Acid on the Photostability and Self-Recovery of Cesium Lead Bromide Nanocrystals

Kano K., Iso Y., Isobe T.

ECS Journal of Solid State Science and Technology （ECS Journal of Solid State Science and Technology) 12 （ 5 ） 2023.05

Joint Work, ISSN 21628769

　View Summary

Photoinduced desorption of surface ligands causes photodegradation of nanophosphors due to enhanced non-radiative relaxation, which is attributed to generated surface defects. We previously reported the self-recovery of photodegraded CsPbBr3 nanocrystals (NCs) and revealed that its mechanism can be attributed to readsorption of the desorbed surface ligands. Thus, using different surface ligands would change the photodegradation and subsequent self-recovery behaviors. Accordingly, in the present work, perfluorodecanoic acid (PFDA) was added to pre-synthesized CsPbBr3 NCs modified with oleic acid and oleylamine to evaluate its effects on photodegradation and subsequent self-recovery. The as-prepared NCs (OA-NCs) and PFDA-modified NCs (PFDA-NCs) were dispersed in nanocomposite ethylene-vinyl acetate resin films to suppress concentration quenching. OA-NCs showed monotonical photoluminescence (PL) decrease under blue excitation light and self-recovery during subsequent dark storage. In contrast, the PFDA-NCs exhibited temporary PL enhancement under excitation irradiation. The photo-activation is attributed to optimization of the adsorption states of the surface ligands in the early stage, while the influence of photodegradation due to ligand desorption becomes dominant later. However, increased PFDA modification prevented self-recovery, indicating that desorbed PFDA may be resistant to readsorption on the NC surface.
- Access to Document (DOI)
Open system synthesis of narrow-bandwidth red-fluorescent carbon quantum dots with a function of multi-metal ion sensing

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

Journal of Materials Chemistry C （Journal of Materials Chemistry C) 11 （ 12 ） 4143 - 4152 2023

Joint Work, ISSN 2050-7526

　View Summary

Carbon quantum dots (CQDs) are environmentally friendly phosphors. However, there have been few reports on red-emitting CQDs with narrow-bandwidths, all of which were synthesized via solvothermal methods using autoclaves. Here, red-emitting CQDs were synthesized from 4,6-diaminoresorcinol dihydrochloride (DAR), which is an aromatic compound with electron-donating hydroxy and amino groups. The synthesis involved heating at 180 °C for 6 h in a high-boiling-point 1,2-pentanediol solvent in an open system without using autoclaves and catalysts. The DAR-derived-CQDs in ethanol exhibited red photoluminescence with a 0.14 eV full width at half-maximum that was comparable to that of narrow-bandwidth blue-fluorescent phloroglucinol (PG)-derived-CQDs. The red emission was attributed to a weakened quantum-size effect and electron-donating NH2 groups. The hydroxy groups of PG-derived-CQDs interacted with Al3+ and Fe3+ ions, resulting in fluorescence quenching. DAR-derived-CQDs have hydroxy and amino groups, which facilitate the fluorescence quenching for Al3+, Fe3+, Cu2+, and Pb2+ ions.
- Access to Document (DOI)

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

Optimizing synthetic conditions of carbon dots with narrow-bandwidth fluorescence

Isobe, Tetsuhiko

学事振興資金研究成果実績報告書（慶應義塾大学) 2021
Optimizing synthetic conditions of carbon dots with narrow-bandwidth fluorescence

Isobe, Tetsuhiko

学事振興資金研究成果実績報告書（慶應義塾大学) 2020
Improvement of properties of solar cells by quantum dots with the function of UV-visible wavelength conversion

Isobe, Tetsuhiko

科学研究費補助金研究成果報告書 2020
Preparation, characterization, and application of near-UV → red conversion fluorescent nanosheets and their composite films

Isobe, Tetsuhiko

科学研究費補助金研究成果報告書 2017
Preparation and characterization of biocompatible composite beads with fluorescent nanoparticles

Isobe, Tetsuhiko

科学研究費補助金研究成果報告書 2013

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
- Access to Document (DOI)
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

Presentations 【 Display / hide 】

臭化セシウム鉛ナノキューブの配列制御による光安定性の向上

橋本　翔太，佐々木　萌香，磯　由樹，緒明　佑哉，磯部　徹彦，今井　宏明

第12回CSJ化学フェスタ2022 (タワーホール船堀，東京) ,

2022.10
,
Poster presentation
狭帯域蛍光および蛍光ソルバトクロミズムを示すグラフェン量子ドットの大量液相合成

越智　幸乃，片上　凜香，小椋　章弘，高尾　賢一，磯　由樹，磯部　徹彦

第12回CSJ化学フェスタ2022 (タワーホール船堀，東京) ,

2022.10
,
Poster presentation
狭帯域赤色蛍光を示すカーボン量子ドットの液相合成

片上　凜香，佐藤　康平，小椋　章弘，高尾　賢一，磯　由樹，磯部　徹彦

第12回CSJ化学フェスタ2022 (タワーホール船堀，東京) ,

2022.10
,
Poster presentation
Surface Engineering of Fluorescent CsPbBr3 and Carbon Quantum Dots by Perfluorocarboxylic Acid

Tetsuhiko Isobe, Yoshiki Iso

242nd ECS Meeting (Atlanta, USA) ,

2022.10
,
Oral presentation (invited, special)
親水化処理したCuInS2/ZnS量⼦ドットの⽔系電気泳動堆積法による透明蛍光膜の作製

森本　敦主，磯　由樹，磯部　徹彦

第83回応用物理学会秋季学術講演会 (東北大学川内北キャンパス，仙台) ,

2022.09
,
Oral presentation (general)

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

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.
Preparation and characterization of composites consisting of nanoparticles with dual functions of fluorescence and magnetism

2008

-

2010

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

　View Summary

YVO_4:Bi^<3+>,Eu^<3+> nanoparticles emitting red under the excitation of ultraviolet light were hybridized with PMMA mirobeads through electrostatic interaction. In addition, YAG:Ce^<3+> nanoparticles emitting green under the excitation of blue light as well as YAG/YIG core/shell nanoparticles were hybridized with PMMA mirobeads through electrostatic interaction.

Works 【 Display / hide 】

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

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

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.

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

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

Memberships in Academic Societies 【 Display / hide 】

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

Committee Experiences 【 Display / hide 】

2022.01

-

Present

会長, 蛍光体同学会
2007.01

-

Present

幹事, 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