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

Pure

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 】

Greenish yellow-emitting carbon dot-based films for luminescent solar concentrator applications

Liu Y., Iso Y., Isobe T.

Journal of Materials Chemistry C 13 ( 2 ) 786 - 792 2025.01

Joint Work, ISSN 20507526

　View Summary

Currently, most carbon dots (CDs) are synthesized from carbon-based materials in autoclaves with high pressure, and then applied in various fields. This work explored the facile synthesis of CDs at atmospheric pressure, which were then purified and embedded in the ethylene-vinyl acetate (EVA) copolymer to form CDs@EVA films and applied in luminescent solar concentrator (LSC) devices. First, crude CDs were synthesized by refluxing p-phenylenediamine (p-PD) in diphenyl ether at 250 °C for 2 h under ambient air conditions, followed by purification using silica gel column chromatography to obtain purified CDs with a photoluminescence (PL) quantum yield of 56% and an average particle size of 15.1 ± 4.4 nm. The CDs@EVA films were fabricated at CD concentrations of 0.05 wt%, 0.10 wt%, and 0.15 wt%, and their thickness was varied from ∼100 μm to ∼500 μm. The yellowish-transparent CDs@EVA films exhibited greenish-yellow emission with absorption peaks at 350 nm and 470 nm, corresponding to the n-π* transition of C 00000000 00000000 00000000 00000000 11111111 00000000 11111111 00000000 00000000 00000000 N bonds and the π-π* transition between the highest occupied molecular orbital and the lowest unoccupied molecular orbital of π-conjugated electrons. The PL intensity reached its maximum at 0.05 wt% CD concentration and 408 μm thickness due to self-absorption of emission from CDs. According to the current-voltage curve measurements under AM1.5G simulated sunlight, this film exhibited the maximum short-circuit current (Isc) and power conversion efficiency (η) of the LSC device. Additionally, incident photon-to-current efficiency spectrum measurements revealed that the enhanced Isc and η in CDs@EVA films mainly resulted from emission by absorption through the n-π* and π-π* transitions.
- Access to Document (DOI)
Photoluminescence enhancement of 1,2,4-triaminobenzene molecules by modification with hydrolytically polycondensed 3-aminopropyltriethoxysilane

Tan H., Iso Y., Isobe T.

Journal of Luminescence 277 2025.01

Joint Work, ISSN 00222313

　View Summary

Small-molecule dyes with longer wavelength and higher photoluminescence quantum yield (PLQY) in water have attracted increasing attention due to their bright potential in fluorescence analysis technologies. Here, a red-emitting fluorescent dye of 1,2,4-triaminobenzene (TriAB) was modified with 3-aminopropyltriethoxysilane (APTES) to avoid contact with water molecules and to suppress fluorescence quenching due to O-H vibrations in water. The formation of a silica-like structure from hydrolytically polycondensed APTES was confirmed by X-ray diffractometry and Fourier-transform infrared absorption spectroscopy. Modification of TriAB with hydrolytically polycondensed APTES induced orange emission in the powder state, although TriAB powder did not exhibit any fluorescence before modification. The PLQY of APTES-modified TriAB in water was 11.1 %, which was higher than that of TriAB in water, 4.5 %. These results confirmed that the APTES derived silica-like matrix shielded TriAB from both water and intermolecular interactions with other TriAB molecules, overcoming fluorescence quenching.
- Access to Document (DOI)
Fabrication of CuInS<inf>2</inf>/ZnS quantum dot nanocomposite films and investigation of their influence on performance of soda glass-based luminescent solar concentrators

Imakiire Y., Iso Y., Isobe T.

Journal of Materials Chemistry C 13 ( 8 ) 4078 - 4088 2025

Joint Work, ISSN 20507526

　View Summary

The power generation performance of luminescent solar concentrators (LSCs) is decreased by unignorable optical losses including self-absorption of luminescence by the phosphor and optical absorption by the light guide plate. To address the optical loss due to self-absorption, this research focused on the use of core/shell CuInS2 (CIS)/ZnS quantum dots (QDs) with a large Stokes shift. The QDs were dispersed in ethylene-vinyl acetate (EVA) copolymer to fabricate transparent fluorescent nanocomposite films. LSCs were prepared with the nanocomposite films and soda glass plate, a common building material to investigate the effect of optical absorption by the light guide plate on the power generation performance. Synthesized QDs showed yellow emission at 587 nm with a high photoluminescence quantum yield (PLQY) of 61.1%, and their large Stokes shift of 0.82 eV reduced self-absorption, making them suitable for LSC applications. We evaluated the effects of QD concentration, film thickness, light guide plate material, and film position on the performance of the LSCs. Optimized performance was observed at a QD concentration of 6.2 wt% and film thickness of 324 μm, showing 1.71-fold higher photocurrent and 3.58-fold larger area of incident photon-to-current efficiency spectrum compared to without film. Replacing soda glass with low-absorption white glass increased power generation by fourfold. This reveals the significant absorption losses of the PL and scattered incident light by soda glass. Despite the considerable optical loss, soda glass is a necessary component in a light guide plate to promote the use of LSCs as building materials. Our findings indicate that QDs with a narrow emission peak at ∼520 nm are required to minimize the absorption loss by soda glass.
- Access to Document (DOI)
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.
- Access to Document (DOI)
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.
- 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) 2022
Development of advanced liquid-phase synthesis of carbon dots with controlled photoluminescence properties

Isobe, Tetsuhiko

科学研究費補助金研究成果報告書 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) 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

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 】

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

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.

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

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 】

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

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