業績情報

• 1D Crystallographic Etching of Few‐Layer WS₂
  Shisheng Li; Yung‐Chang Lin; Yiling Chiew; Yunyun Dai; Zixuan Ning; Yaming Zhang; Hideaki Nakajima; Hong En Lim; Jing Wu; Yasuhisa Neitoh; Toshiya Okazaki; Yang Sun; Zhipei Sun; Kazu Suenaga; Yoshiki Sakuma; Kazuhito Tsukagoshi; Takaaki Taniguchi
  Advanced Functional Materials, 巻：34, 号：46, 2024年10月, ［査読有り］
  Abstract
  
  Layer number‐dependent band structures and symmetry are vital for the electrical and optical characteristics of 2D transition metal dichalcogenides (TMDCs). Harvesting 2D TMDCs with tunable thickness and properties can be achieved through top‐down etching and bottom‐up growth strategies. In this study, a pioneering technique that utilizes the migration of in situ generated Na‐W‐S‐O droplets to etch out 1D nanotrenches in few‐layer WS₂ is reported. 1D WS₂ nanotrenches are successfully fabricated on the optically inert bilayer WS_2, showing pronounced photoluminescence and second harmonic generation signals. Additionally, the modulation of inkjet‐printed Na₂WO₄‐Na₂SO₄ particles to switch between the etching and growth modes by manipulating the sulfur supply is demonstrated. This versatile approach enables the creation of 1D nanochannels on 2D TMDCs. The research presents exciting prospects for the top‐down and bottom‐up fabrication of 1D‐2D mixed‐dimensional TMDC nanostructures, expanding their use for electronic and optoelectronic applications.
  Wiley, 研究論文（学術雑誌）
  DOI：https://doi.org/10.1002/adfm.202405665
  DOI ID：10.1002/adfm.202405665, ISSN：1616-301X, eISSN：1616-3028
• Vapor-phase growth of one-dimensional transition metal chalcogenide wires　　　　　　　　　　　　　　　
  Yusuke Nakanishi; Hong En Lim; Yasumitsu Miyata
  JSAP Review, 巻：2023, 開始ページ：230422-1, 終了ページ：230422-5, 2023年08月, ［査読有り］, ［招待有り］
  DOI：https://doi.org/10.11470/jsaprev.230422
  DOI ID：10.11470/jsaprev.230422
• 1次元遷移金属カルコゲナイド細線の気相成長　　　　　　　　　　　　　　　
  中西 勇介; リム ホンエン; 宮田 耕充
  応用物理, 巻：92, 号：5, 開始ページ：292, 終了ページ：296, 2023年05月, ［査読有り］, ［招待有り］
  DOI：https://doi.org/10.11470/oubutsu.92.5_292
  DOI ID：10.11470/oubutsu.92.5_292
• Multilayer In-Plane Heterostructures Based on Transition Metal Dichalcogenides for Advanced Electronics　　　　　　　　　　　　　　　
  Hiroto Ogura; Seiya Kawasaki; Zheng Liu; Takahiko Endo; Mina Maruyama; Yanlin Gao; Yusuke Nakanishi; Hong En Lim; Kazuhiro Yanagi; Toshifumi Irisawa; Keiji Ueno; Susumu Okada; Kosuke Nagashio; Yasumitsu Miyata
  ACS Nano, 2023年04月, ［査読有り］
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1021/acsnano.2c11927
  DOI ID：10.1021/acsnano.2c11927, ORCID：129774255
• High-throughput dry transfer and excitonic properties of twisted bilayers based on CVD-grown transition metal dichalcogenides　　　　　　　　　　　　　　　
  Hibiki Naito; Yasuyuki Makino; Wenjin Zhang; Tomoya Ogawa; Takahiko Endo; Takumi Sannomiya; Masahiko Kaneda; Kazuki Hashimoto; Hong En Lim; Yusuke Nakanishi; Kenji Watanabe; Takashi Taniguchi; Kazunari Matsuda; Yasumitsu Miyata
  Nanoscale Advances, 2023年, ［査読有り］
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1039/D3NA00371J
  DOI ID：10.1039/D3NA00371J, ORCID：141687769
• Formation of a Two-Dimensional Electronic System in Laterally Assembled WTe Nanowires　　　　　　　　　　　　　　　
  Hiroshi Shimizu; Jiang Pu; Zheng Liu; Hong En Lim; Mina Maruyama; Yusuke Nakanishi; Shunichiro Ito; Iori Kikuchi; Takahiko Endo; Kazuhiro Yanagi; Yugo Oshima; Susumu Okada; Taishi Takenobu; Yasumitsu Miyata
  ACS Applied Nano Materials, 2022年05月, ［査読有り］
  American Chemical Society ({ACS}), 研究論文（学術雑誌）
  DOI：https://doi.org/10.1021/acsanm.2c00377
  DOI ID：10.1021/acsanm.2c00377, ORCID：110681018
• Nanowire-to-Nanoribbon Conversion in Transition-Metal Chalcogenides: Implications for One-Dimensional Electronics and Optoelectronics　　　　　　　　　　　　　　　
  Hong En Lim; Zheng Liu; Juan Kim; Jiang Pu; Hiroshi Shimizu; Takahiko Endo; Yusuke Nakanishi; Taishi Takenobu; Yasumitsu Miyata
  ACS Applied Nano Materials, 2022年02月, ［査読有り］, ［筆頭著者, 責任著者］
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1021/acsanm.1c03160
  DOI ID：10.1021/acsanm.1c03160, ORCID：104849071
• Control of Thermal Conductance across Vertically Stacked Two-Dimensional van der Waals Materials via Interfacial Engineering　　　　　　　　　　　　　　　
  Wenyu Yuan; Kan Ueji; Takashi Yagi; Takahiko Endo; Hong En Lim; Yasumitsu Miyata; Yohei Yomogida; Kazuhiro Yanagi
  ACS Nano, 2021年10月, ［査読有り］
  American Chemical Society ({ACS}), 研究論文（学術雑誌）
  DOI：https://doi.org/10.1021/acsnano.1c03822
  DOI ID：10.1021/acsnano.1c03822, ORCID：100741948
• Mixed-Salt Enhanced Chemical Vapor Deposition of Two-Dimensional Transition Metal Dichalcogenides　　　　　　　　　　　　　　　
  Shisheng Li; Yung-Chang Lin; Jinhua Hong; Bo Gao; Hong En Lim; Xu Yang; Song Liu; Yoshitaka Tateyama; Kazuhito Tsukagoshi; Yoshiki Sakuma; Kazu Suenaga; Takaaki Taniguchi
  Chemistry of Materials, 2021年09月, ［査読有り］
  American Chemical Society ({ACS}), 研究論文（学術雑誌）
  DOI：https://doi.org/10.1021/acs.chemmater.1c01652
  DOI ID：10.1021/acs.chemmater.1c01652, ORCID：99632170
• Tunable Doping of Rhenium and Vanadium into Transition Metal Dichalcogenides for Two‐Dimensional Electronics　　　　　　　　　　　　　　　
  Shisheng Li; Jinhua Hong; Bo Gao; Yung‐Chang Lin; Hong En Lim; Xueyi Lu; Jing Wu; Song Liu; Yoshitaka Tateyama; Yoshiki Sakuma; Kazuhito Tsukagoshi; Kazu Suenaga; Takaaki Taniguchi
  Advanced Science, 2021年06月, ［査読有り］
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1002/advs.202004438
  DOI ID：10.1002/advs.202004438, ORCID：91653920
• Wafer-Scale Growth of One-Dimensional Transition-Metal Telluride Nanowires　　　　　　　　　　　　　　　
  Hong En Lim; Yusuke Nakanishi; Zheng Liu; Jiang Pu; Mina Maruyama; Takahiko Endo; Chisato Ando; Hiroshi Shimizu; Kazuhiro Yanagi; Susumu Okada; Taishi Takenobu; Yasumitsu Miyata
  Nano Letters, 巻：21, 号：1, 開始ページ：243, 終了ページ：249, 2021年01月, ［査読有り］, ［筆頭著者, 責任著者］
  American Chemical Society ({ACS}), 研究論文（学術雑誌）
  DOI：https://doi.org/10.1021/acs.nanolett.0c03456
  DOI ID：10.1021/acs.nanolett.0c03456, ORCID：85198754
• Air-stable and efficient electron doping of monolayer MoS2 by salt–crown ether treatment　　　　　　　　　　　　　　　
  Hiroto Ogura; Masahiko Kaneda; Yusuke Nakanishi; Yoshiyuki Nonoguchi; Jiang Pu; Mari Ohfuchi; Toshifumi Irisawa; Hong En Lim; Takahiko Endo; Kazuhiro Yanagi; Taishi Takenobu; Yasumitsu Miyata
  Nanoscale, 2021年, ［査読有り］
  Royal Society of Chemistry ({RSC}), 研究論文（学術雑誌）
  DOI：https://doi.org/10.1039/D1NR01279G
  DOI ID：10.1039/D1NR01279G, ORCID：93094544
• On/Off Boundary of Photocatalytic Activity between Single- and Bilayer MoS2　　　　　　　　　　　　　　　
  Takaaki Taniguchi; Leanddas Nurdiwijayanto; Shisheng Li; Hong En Lim; Yasumitsu Miyata; Xueyi Lu; Renzhi Ma; Dang-Ming Tang; Shigenori Ueda; Kazuhito Tsukagoshi; Takayoshi Sasaki; Minoru Osada
  ACS Nano, 2020年06月, ［査読有り］
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1021/acsnano.9b09253
  DOI ID：10.1021/acsnano.9b09253, ORCID：74154407
• Direct and Indirect Exciton Dynamics in Few-Layered ReS2 Revealed by Photoluminescence and Pump-Probe Spectroscopy　　　　　　　　　　　　　　　
  Xiaofan Wang; Keisuke Shinokita; Hong En Lim; Nur Baizura Mohamed; Yuhei Miyauchi; Nguyen Thanh Cuong; Susumu Okada; Kazunari Matsuda
  Advanced Functional Materials, 巻：29, 号：6, 2019年02月, ［査読有り］
  Atomically thin-layered ReS2 with a distorted 1T structure has attracted attention because of its intriguing optical and electronic properties. Here, the direct and indirect exciton dynamics of a three-layered ReS2 is investigated by polarization-resolved transient photoluminescence (PL) and ultrafast pump-probe spectroscopy. The various time scales of the decay signals of the time-resolved PL (<10 ps), with monitoring of the populations of electron–hole pairs (exciton), and the transient differential reflectance (≈1 and 100 ps), with monitoring of the populations of electrons and/or holes in the excited states, are observed. These results reveal the characteristic exciton dynamics: rapid relaxation of direct excitons (electron–hole pairs) and slow relaxation of the momentum-mismatched indirect excitons accompanied by a one-phonon emission process. These findings provide important information regarding the indirect bandgap nature of few-layered ReS2 and its characteristic exciton dynamics, boosting the understanding of the novel electronic and optical properties of atomically thin-layered ReS2.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1002/adfm.201806169
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  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85059149888&origin=inward
  DOI ID：10.1002/adfm.201806169, ISSN：1616-301X, eISSN：1616-3028, SCOPUS ID：85059149888
• Monolayer MoS2 growth at the Au–SiO2 interface　　　　　　　　　　　　　　　
  Hong En Lim; Toshifumi Irisawa; Naoya Okada; Mitsuhiro Okada; Takahiko Endo; Yusuke Nakanishi; Yutaka Maniwa; Yasumitsu Miyata
  Nanoscale, 2019年, ［査読有り］, ［筆頭著者, 責任著者］
  Royal Society of Chemistry ({RSC}), 研究論文（学術雑誌）
  DOI：https://doi.org/10.1039/C9NR05119H
  DOI ID：10.1039/C9NR05119H, ORCID：60994005
• Restoring the intrinsic optical properties of CVD-grown MoS2 monolayers and their heterostructures　　　　　　　　　　　　　　　
  Kana Kojima; Hong En Lim; Zheng Liu; Wenjin Zhang; Tetsuki Saito; Yusuke Nakanishi; Takahiko Endo; Yu Kobayashi; Kenji Watanabe; Takashi Taniguchi; Kazunari Matsuda; Yutaka Maniwa; Yuhei Miyauchi; Yasumitsu Miyata
  Nanoscale, 巻：11, 号：27, 開始ページ：12798, 終了ページ：12803, 2019年, ［査読有り］
  Royal Society of Chemistry ({RSC}), 研究論文（学術雑誌）
  DOI：https://doi.org/10.1039/C9NR01481K
  DOI ID：10.1039/C9NR01481K, ORCID：58379625
• Photoluminescence quantum yields for atomically thin-layered ReS2: Identification of indirect-bandgap semiconductors　　　　　　　　　　　　　　　
  Nur Baizura Mohamed; Keisuke Shinokita; Xiaofan Wang; Hong En Lim; Dezhi Tan; Yuhei Miyauchi; Kazunari Matsuda
  Applied Physics Letters, 巻：113, 号：12, 2018年09月, ［査読有り］
  Rhenium dichalcogenides have attracted considerable attention as new members of group VII layered semiconductor transition-metal dichalcogenides (TMDs) with respect to fundamental physics and potential applications. In this study, room-temperature photoluminescence (PL) spectra, as well as PL quantum yields (QYs) of thin-layer rhenium disulfide (ReS2), were evaluated. Low PL QYs of ∼10-4 were determined from a monolayer thickness to seven layers (1-7L) of ReS2 regardless of the layer number. These low PL QYs strongly suggest that the ReS2 is an indirect-bandgap semiconductor from a monolayer limit to the bulk, which is in contrast to those observed for group VI TMDs (MX2: M = Mo and W; X = S and Se). Our experimental findings will provide valuable information for the electronic and optical device applications in atomically thin-layered ReS2.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1063/1.5037116
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85053843288&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85053843288&origin=inward
  DOI ID：10.1063/1.5037116, ISSN：0003-6951, SCOPUS ID：85053843288
• Efficient Photocarrier Transfer and Effective Photoluminescence Enhancement in Type I Monolayer MoTe2/WSe2 Heterostructure　　　　　　　　　　　　　　　
  Takao Yamaoka; Hong En Lim; Sandhaya Koirala; Xiaofan Wang; Keisuke Shinokita; Mina Maruyama; Susumu Okada; Yuhei Miyauchi; Kazunari Matsuda
  Advanced Functional Materials, 巻：28, 号：35, 2018年08月, ［査読有り］
  Artificial van der Waals heterostructures of 2D layered materials are attractive from the viewpoint of the possible discovery of new physics together with improved functionalities. Stacking various combinations of atomically thin semiconducting transition metal dichalcogenides, MX2 (M = Mo, W; X = S, Se, Te) with a hexagonal crystal structure, typically leads to the formation of a staggered Type II band alignment in the heterostructure, where electrons and holes are confined in different layers. Here, the comprehensive studies are performed on heterostructures prepared from monolayers of WSe2 and MoTe2 using differential reflectance, photoluminescence (PL), and PL excitation spectroscopy. The MoTe2/WSe2 heterostructure shows strong PL from the MoTe2 layer at ≈1.1 eV, which is different from the quenched PL from the WSe2 layer. Moreover, enhancement of PL intensity from the MoTe2 layer is observed because of the near-unity highly efficient photocarrier transfer from WSe2 to MoTe2. These experimental results suggest that the MoTe2/WSe2 heterostructure has a Type I band alignment where electrons and holes are confined in the MoTe2 layer. The findings extend the diversity and usefulness of ultrathin layered heterostructures based on transition metal dichalcogenides, leading to possibilities toward future optoelectronic applications.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1002/adfm.201801021
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85050915529&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85050915529&origin=inward
  DOI ID：10.1002/adfm.201801021, ISSN：1616-301X, eISSN：1616-3028, SCOPUS ID：85050915529
• High Bending Durability of Efficient Flexible Perovskite Solar Cells Using Metal Oxide Electron Transport Layer　　　　　　　　　　　　　　　
  Fengjiu Yang; Jiewei Liu; Hong En Lim; Yasuhisa Ishikura; Keisuke Shinokita; Yuhei Miyauchi; Atsushi Wakamiya; Yasujiro Murata; Kazunari Matsuda
  Journal of Physical Chemistry C, 巻：122, 号：30, 開始ページ：17088, 終了ページ：17095, 2018年08月, ［査読有り］
  With a rapid progress in photovoltaic performance over the past several years, organic-inorganic perovskite solar cells (PSCs) have been regarded as a promising candidate for next-generation photovoltaic devices such as lightweight and flexible photovoltaic equipment and portable systems. However, the photovoltaic performance and its durability during the mechanical bending test of flexible PSCs (fPSCs) are insufficient for the realistic application. This inadequacy stems from a lack of a superior electron transport material (ETM) for fPSCs. Here, we describe the application of SnO2 as an ETM for fPSCs (SnO2-fPSCs), achieving outstanding photovoltaic performance and excellent mechanical bending durability. We demonstrate the high power conversion efficiency (PCE) of 17.1 and 16.2% with negligible hysteresis and the high stabilized power output of 17.0 and 15.9% of normal-architecture SnO2-fPSCs with a photoactive area of 0.1 and 1.0 cm2, respectively. Moreover, the SnO2-fPSCs exhibit an excellent bending durability that retains 76.5% of the initial PCE even after 2000 times harsh bending cycle with a small bending radius of 4.0 mm on 0.1 cm2 active area.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1021/acs.jpcc.8b05008
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  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85051141854&origin=inward
  DOI ID：10.1021/acs.jpcc.8b05008, ISSN：1932-7447, eISSN：1932-7455, SCOPUS ID：85051141854
• Ultrafast Charge Transfer and Relaxation Dynamics in Polymer-Encapsulating Single-Walled Carbon Nanotubes: Polythiophene and Coronene Polymer　　　　　　　　　　　　　　　
  Arao Nakamura; Ken Ichi Yamanaka; Kenshi Miyaura; Hong En Lim; Kazunari Matsuda; Boanerges Thendie; Yasumitsu Miyata; Taketo Kochi; Susumu Okada; Hisanori Shinohara
  Journal of Physical Chemistry C, 巻：122, 号：29, 開始ページ：16940, 終了ページ：16949, 2018年07月, ［査読有り］
  We investigate the photophysical properties of polymer-encapsulating single-walled carbon nanotubes (SWNTs) using absorption spectroscopy, photoconductivity spectroscopy, and femtosecond pump-probe spectroscopy. In a polythiophene (PT)-encapsulating SWNT film, one or two PT layers are encapsulated within SWNTs, depending on the tube diameter. For single encapsulated PT layers, the photoconductivity action spectrum shows a large photocurrent signal corresponding to absorption bands associated with PT exciton and continuum states, indicating charge transfer between the PT and the small-diameter SWNT. Pump-probe measurements show that electron transfer to the SWNT occurs in 0.53 ps and electrons then recombine with holes remaining in the PT in 11 ps. In a coronene-polymer-encapsulating SWNT film, weak absorption bands at 1.7 and 3.4 eV are observed in addition to the SWNT spectrum. Band calculations allow these to be assigned to optical transitions between the electronic states originating from the coronene polymer, hybridized with those of the SWNT. The pump-probe measurements reveal fast electron relaxation (0.38 ps) from the conduction band of the coronene polymer to the lowest conduction band originating from the SWNT and subsequent recombination (1.5 ps) of these electrons with holes in the top valence band originating from the coronene polymer.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1021/acs.jpcc.8b03757
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  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85050905266&origin=inward
  DOI ID：10.1021/acs.jpcc.8b03757, ISSN：1932-7447, eISSN：1932-7455, SCOPUS ID：85050905266
• Carrier Transport and Photoresponse in GeSe/MoS2 Heterojunction p–n Diodes　　　　　　　　　　　　　　　
  Dezhi Tan; Xiaofan Wang; Wenjin Zhang; Hong En Lim; Keisuke Shinokita; Yuhei Miyauchi; Mina Maruyama; Susumu Okada; Kazunari Matsuda
  Small, 巻：14, 号：22, 2018年05月, ［査読有り］
  Simple stacking of thin van der Waals 2D materials with different physical properties enables one to create heterojunctions (HJs) with novel functionalities and new potential applications. Here, a 2D material p–n HJ of GeSe/MoS2 is fabricated and its vertical and horizontal carrier transport and photoresponse properties are studied. Substantial rectification with a very high contrast (>104) through the potential barrier in the vertical-direction tunneling of HJs is observed. The negative differential transconductance with high peak-to-valley ratio (>105) due to the series resistance change of GeSe, MoS2, and HJs at different gate voltages is observed. Moreover, strong and broad-band photoresponse via the photoconductive effect are also demonstrated. The explored multifunctional properties of the GeSe/MoS2 HJs are expected to be important for understanding the carrier transport and photoresponse of 2D-material HJs for achieving their use in various new applications in the electronics and optoelectronics fields.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1002/smll.201704559
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  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85046036580&origin=inward
  DOI ID：10.1002/smll.201704559, ISSN：1613-6810, eISSN：1613-6829, PubMed ID：29700968, SCOPUS ID：85046036580
• Band gap modification and photoluminescence enhancement of graphene nanoribbon filled single-walled carbon nanotubes　　　　　　　　　　　　　　　
  A. I. Chernov; P. V. Fedotov; H. E. Lim; Y. Miyata; Z. Liu; K. Sato; K. Suenaga; H. Shinohara; E. D. Obraztsova
  Nanoscale, 巻：10, 号：6, 開始ページ：2936, 終了ページ：2943, 2018年02月, ［査読有り］
  Molecule encapsulation inside the single-walled carbon nanotube (SWCNT) core has been demonstrated to be a successful route for the modification of nanotube properties. SWCNT diameter-dependent filling results in band gap modification together with the enhancement of photoluminescence quantum yield. However, the interaction between the inner structure and the outer shell is complex. It depends on the orientation of the molecules inside, the geometry of the host nanotube and on several other mechanisms determining the resulting properties of the hybrid nanosystem. In this work we study the influence of encapsulated graphene nanoribbons on the optical properties of the host single-walled carbon nanotubes. The interplay of strain and dielectric screening caused by the internal environment of the nanotube affects its band gap. The photoluminescence of the filled nanotubes becomes enhanced when the graphene nanoribbons are polymerized inside the SWCNTs at low temperatures. We show a gradual photoluminescence quenching together with a selective signal enhancement for exact nanotube geometries, specifically (14,6) and (13,8) species. A precise adjustment of the optical properties and an enhancement of the photoluminescence quantum yield upon filling for nanotubes with specific diameters were assigned to optimal organization of the inner structures.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1039/c7nr07054c
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  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85041803889&origin=inward
  DOI ID：10.1039/c7nr07054c, ISSN：2040-3364, eISSN：2040-3372, PubMed ID：29369315, SCOPUS ID：85041803889
• Roles of Polymer Layer in Enhanced Photovoltaic Performance of Perovskite Solar Cells via Interface Engineering　　　　　　　　　　　　　　　
  Fengjiu Yang; Hong En Lim; Feijiu Wang; Masashi Ozaki; Ai Shimazaki; Jiewei Liu; Nur Baizura Mohamed; Keisuke Shinokita; Yuhei Miyauchi; Atsushi Wakamiya; Yasujiro Murata; Kazunari Matsuda
  Advanced Materials Interfaces, 巻：5, 号：3, 2018年02月, ［査読有り］
  Perovskite solar cells (PSCs) have attracted intensive attention as the most promising next-generation photovoltaic technology because they both enable accelerated development of photovoltaic performance and are compatible with low-cost fabrication methods. The strategy of interface engineering of the perovskite layer in PSCs is expected to result in further enhancement of the power conversion efficiency (PCE) of PSCs via minimizing the charge recombination loss. Here, a high current–voltage (stabilized power output) PCE of 20.4% (19.9%) in CH3NH3PbI3 PSCs under reverse scanning conditions is demonstrated by incorporating a solution-processed polymer layer of poly(methyl methacrylate) (PMMA) between the perovskite photoactive layer and the hole transport layer. Moreover, steady-state and time-resolved photoluminescence spectroscopy and impedance spectroscopy are used to reveal the mechanism of the enhancement of the photovoltaic performance and its stability by the PMMA layer in a CH3NH3PbI3 PSC device. The morphology modification, surface passivation, and protection of the perovskite layer by the insulating PMMA layer substantially contribute to the enhancement of photovoltaic performance and its stability, despite a slight reduction of the charge extraction efficiency. The demonstrated high PCEs and insights obtained into the working mechanism of the PMMA layer pave the way for the industrial application of CH3NH3PbI3 PSCs.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1002/admi.201701256
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  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85038626762&origin=inward
  DOI ID：10.1002/admi.201701256, eISSN：2196-7350, SCOPUS ID：85038626762
• Long radiative lifetimes of excitons in monolayer transition-metal dichalcogenides MX 2 (M = Mo, W; X = S, Se)　　　　　　　　　　　　　　　
  Nur Baizura Mohamed; Hong En Lim; Feijiu Wang; Sandhaya Koirala; Shinichiro Mouri; Keisuke Shinokita; Yuhei Miyauchi; Kazunari Matsuda
  Applied Physics Express, 巻：11, 号：1, 2018年01月, ［査読有り］
  We studied the effective exciton radiative lifetimes of monolayer two-dimensional transition-metal dichalcogenides MX 2 (M = Mo, W; X = S, Se). The photoluminescence (PL) quantum yield and PL decay time were measured for monolayer MoS2, MoSe2, WS2, and WSe2 at room temperature. Effective exciton radiative lifetimes of >10 ns were determined from the PL quantum yield of 10-2 to 10-3 and the PL decay time of several hundred picoseconds. The results are explained on the basis of the long radiative lifetime of bright excitons at a low temperature limit, a finite exciton coherence area of several square nanometers, and the population of dark exciton states.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.7567/APEX.11.015201
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85039998281&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85039998281&origin=inward
  DOI ID：10.7567/APEX.11.015201, ISSN：1882-0778, eISSN：1882-0786, SCOPUS ID：85039998281
• Anisotropic optical and electronic properties of two-dimensional layered germanium sulfide　　　　　　　　　　　　　　　
  Dezhi Tan; Hong En Lim; Feijiu Wang; Nur Baizura Mohamed; Shinichiro Mouri; Wenjin Zhang; Yuhei Miyauchi; Mari Ohfuchi; Kazunari Matsuda
  Nano Research, 巻：10, 号：2, 開始ページ：546, 終了ページ：555, 2017年02月, ［査読有り］
  Two-dimensional (2D) layered materials, transition-metal dichalcogenides, and black phosphorus have attracted considerable interest from the viewpoints of fundamental physics and device applications. The establishment of new functionalities in anisotropic layered 2D materials is a challenging but rewarding frontier, owing to the remarkable optical properties of these materials and their prospects for new devices. Herein, we report the anisotropic and thickness-dependent optical properties of a 2D layered monochalcogenide of germanium sulfide (GeS). Three Raman-scattering peaks corresponding to the B3g, Ag1, and Ag2 modes with a strong polarization dependence are demonstrated in the GeS flakes, which validates polarized Raman spectroscopy as an effective method for identifying the crystal orientation of anisotropic layered GeS. Photoluminescence (PL) is observed with a peak at ~1.66 eV that originates from the direct optical transition in GeS at room temperature. The polarization-dependent characteristics of the PL, which are revealed for the first time, along with the demonstration of anisotropic absorption, indicate an obvious anisotropic optical transition near the band edge of GeS, which is supported by density functional theory calculations. The significantly thickness-dependent PL is observed and discussed. This anisotropic layered GeS presents opportunities for the discovery of new physical phenomena and will find applications that exploit its anisotropic properties, such as polarization-sensitive photodetectors. [Figure not available: see fulltext.]
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s12274-016-1312-6
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85001838106&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85001838106&origin=inward
  DOI ID：10.1007/s12274-016-1312-6, ISSN：1998-0124, eISSN：1998-0000, SCOPUS ID：85001838106
• Evaluation of photoluminescence quantum yield of monolayer WSe2 using reference dye of 3-borylbithiophene derivative　　　　　　　　　　　　　　　
  Nur Baizura Mohamed; Feijiu Wang; Hong En Lim; Wenjin Zhang; Sandhaya Koirala; Shinichiro Mouri; Yuhei Miyauchi; Kazunari Matsuda
  Physica Status Solidi (B) Basic Research, 巻：254, 号：2, 2017年02月, ［査読有り］
  We studied an evaluation method of photoluminescence (PL) quantum yield of monolayer transition metal chalcogenides (TMDs) on a transparent substrate using a reference dye. A 3-borylbithiophene derivative (C58H49BN2S4) reference dye shows a high PL quantum yield of 36% even in the solid form and the high quantum yield is kept in a Poly(methyl methacrylate) (PMMA) matrix. Moreover, the photon energy of PL is similar to those of monolayer TMDs. These PL characteristics of the reference dye are useful for a evaluation of PL quantum yield in monolayer TMDs. The PL quantum yield of 0.18 ± 0.03% was evaluated for mechanically exfoliated monolayer WSe2 on glass substrate at room temperature.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1002/pssb.201600563
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85012932757&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=85012932757&origin=inward
  DOI ID：10.1002/pssb.201600563, ISSN：0370-1972, eISSN：1521-3951, SCOPUS ID：85012932757
• Fabrication and optical probing of highly extended, ultrathin graphene nanoribbons in carbon nanotubes　　　　　　　　　　　　　　　
  Hong En Lim; Yasumitsu Miyata; Miho Fujihara; Susumu Okada; Zheng Liu; Arifin; Kayoko Sato; Haruka Omachi; Ryo Kitaura; Stephan Irle; Kazu Suenaga; Hisanori Shinohara
  ACS Nano, 巻：9, 号：5, 開始ページ：5034, 終了ページ：5040, 2015年05月, ［査読有り］, ［筆頭著者］
  Nanotemplated growth of graphene nanoribbons (GNRs) inside carbon nanotubes is a promising mean to fabricate ultrathin ribbons with desired side edge configuration. We report the optical properties of the GNRs formed in single-wall carbon nanotubes. When coronene is used as the precursor, extended GNRs are grown via a high-temperature annealing at 700 °C. Their optical responses are probed through the diazonium-based side-wall functionalization, which effectively suppresses the excitonic absorption peaks of the nanotubes without damaging the inner GNRs. Differential absorption spectra clearly show two distinct peaks around 1.5 and 3.4 eV. These peaks are assigned to the optical transitions between the van Hove singularities in the density of state of the GNRs in qualitative agreement with the first-principles calculations. Resonance Raman spectra and transmission electron microscope observations also support the formation of long GNRs.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1021/nn507408m
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84930652603&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84930652603&origin=inward
  DOI ID：10.1021/nn507408m, ISSN：1936-0851, eISSN：1936-086X, SCOPUS ID：84930652603
• Growth of carbon nanotubes via twisted graphene nanoribbons　　　　　　　　　　　　　　　
  Hong En Lim; Yasumitsu Miyata; Ryo Kitaura; Yoshifumi Nishimura; Yoshio Nishimoto; Stephan Irle; Jamie H. Warner; Hiromichi Kataura; Hisanori Shinohara
  Nature Communications, 巻：4, 2013年, ［査読有り］, ［筆頭著者］
  Carbon nanotubes have long been described as rolled-up graphene sheets. It is only fairly recently observed that longitudinal cleavage of carbon nanotubes, using chemical, catalytical and electrical approaches, unzips them into thin graphene strips of various widths, the so-called graphene nanoribbons. In contrast, rolling up these flimsy ribbons into tubes in a real experiment has not been possible. Theoretical studies conducted by Kit et al. recently demonstrated the tube formation through twisting of graphene nanoribbon, an idea very different from the rolling-up postulation. Here we report the first experimental evidence of a thermally induced self-intertwining of graphene nanoribbons for the preferential synthesis of (7, 2) and (8, 1) tubes within parent-tube templates. Through the tailoring of ribbon's width and edge, the present finding adds a radically new aspect to the understanding of carbon nanotube formation, shedding much light on not only the future chirality tuning, but also contemporary nanomaterials engineering. © 2013 Macmillan Publishers Limited.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1038/ncomms3548
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84885364971&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84885364971&origin=inward
  DOI ID：10.1038/ncomms3548, eISSN：2041-1723, SCOPUS ID：84885364971
• Short channel field-effect transistors from highly enriched semiconducting carbon nanotubes　　　　　　　　　　　　　　　
  Justin Wu; Liming Xie; Guosong Hong; Hong En Lim; Boanerges Thendie; Yasumitsu Miyata; Hisanori Shinohara; Hongjie Dai
  Nano Research, 巻：5, 号：6, 開始ページ：388, 終了ページ：394, 2012年06月, ［査読有り］
  Semiconducting single-walled carbon nanotubes (s-SWNTs) with a purity of ~98% have been obtained by gel filtration of arc-discharge grown SWNTs with diameters in the range 1.2-1.6 nm. Multi-laser Raman spectroscopy confirmed the presence of less than 2% of metallic SWNTs (m-SWNTs) in the s-SWNT enriched sample. Measurement of ~50 individual tubes in Pd-contacted devices with channel length 200 nm showed on/off ratios of >104, conductances of 1.38-5.8 μS, and mobilities in the range 40-150 cm2/V·s. Short channel multi-tube devices with ~100 tubes showed lower on/off ratios due to residual m-SWNTs, although the on-current was greatly increased relative to the devices made from individual tubes. © 2012 Tsinghua University Press and Springer-Verlag Berlin Heidelberg.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1007/s12274-012-0219-0
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84862656615&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=84862656615&origin=inward
  DOI ID：10.1007/s12274-012-0219-0, ISSN：1998-0124, eISSN：1998-0000, SCOPUS ID：84862656615
• Transformation of ionic liquid into carbon nanotubes in confined nanospace　　　　　　　　　　　　　　　
  Shimou Chen; Hong En Lim; Yasumitsu Miyata; Ryo Kitaura; Yoshio Bando; Dmitri Golberg; Hisanori Shinohara
  Chemical Communications, 巻：47, 号：37, 開始ページ：10368, 終了ページ：10370, 2011年10月, ［査読有り］
  We have developed a two-step filling process for the nano-reaction of ionic liquid in a tip-closed SWNT, where fullerenes are inserted at the end of the host SWNT as a plug to prevent the leakage of the confined ionic liquid during heat treatment. © 2011 The Royal Society of Chemistry.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1039/c1cc14154f
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=80052525218&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=80052525218&origin=inward
  DOI ID：10.1039/c1cc14154f, ISSN：1359-7345, eISSN：1364-548X, SCOPUS ID：80052525218
• Purity-enhanced bulk synthesis of thin single-wall carbon nanotubes using iron-copper catalysts　　　　　　　　　　　　　　　
  H. E. Lim; Y. Miyata; T. Nakayama; S. Chen; R. Kitaura; H. Shinohara
  Nanotechnology, 巻：22, 号：39, 2011年09月, ［査読有り］, ［筆頭著者］
  We report high purity and high yield synthesis of single-wall carbon nanotubes (SWCNTs) of narrow diameter from iron-copper bimetal catalysts. The SWCNTs with diameter of 0.8-1.2nm are synthesized using the zeolite-supported alcohol chemical vapour deposition method. Single metal and bimetal catalysts are systematically investigated to achieve both the enhancement of SWCNT yield and the suppression of the undesired formation of graphitic impurities. The relative yield and purity of SWCNTs are quantified using optical absorption spectroscopy with an ultracentrifuge-based purification technique. For the single metal catalyst, iron shows the highest catalytic activity compared with the other metals such as cobalt, nickel, molybdenum, copper, and platinum. It has been found that the addition of copper to iron results in the suppression of carbonaceous impurity formation without decreasing the SWCNT yield. The purity-enhanced SWCNT shows fairly low sheet resistance due to the improvement of inter-nanotube contacts. This scalable design of SWCNT synthesis with enhanced purity is therefore a promising tool for shaping future high performance devices. © 2011 IOP Publishing Ltd.
  研究論文（学術雑誌）
  DOI：https://doi.org/10.1088/0957-4484/22/39/395602
  Scopus：https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=80052529854&origin=inward
  Scopus Citedby：https://www.scopus.com/inward/citedby.uri?partnerID=HzOxMe3b&scp=80052529854&origin=inward
  DOI ID：10.1088/0957-4484/22/39/395602, ISSN：0957-4484, eISSN：1361-6528, SCOPUS ID：80052529854

• 現在, 応用物理学会
• 現在, フラーレン・ナノチューブ・グラフェン学会

• ヘテロ固体界面における原子層物質の成長　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 基盤研究(C), 2023年04月 - 2026年03月
  LIM HONGEN, 埼玉大学, 研究代表者
  配分額（総額）：4550000, 配分額（直接経費）：3500000, 配分額（間接経費）：1050000
  課題番号：23K04530
• 原子細線による新奇1次元光電材料の創出　　　　　　　　　　　　　　　
  公益財団法人村田学術振興財団, 研究助成, 2022年06月 - 2024年05月
  Lim Hong En, 埼玉大学, 研究代表者
  配分額（総額）：5000000, 配分額（直接経費）：5000000
• １次元遷移金属カルコゲナイド集合体の制御合成と成長機構の解明　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 若手研究, 2021年04月 - 2023年03月
  LIM HONGEN, 研究代表者
  配分額（総額）：4680000, 配分額（直接経費）：3600000, 配分額（間接経費）：1080000
  1次元ファンデルワールスナノ材料の物性研究やデバイス応用を進めるために、その物質特性に影響を与える集合体の構造を制御しなければならない。本研究では、極めて細い（直径３原子程度の）遷移金属カルコゲナイド原子細線に着目し、化学気相成長法による集合体の合成に取り組んだ。主要な成果として、（１）長尺かつリボン形状のWTe集合体の合成と（２）カルコゲン化によって、原子細線から層状構造を持つ遷移金属ダイカルコゲナイドのナノリボンを作製することに成功した。
  課題番号：21K14498
• 原子層物質と3次元固体接合の作製と界面構造の解明　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 若手研究, 2019年04月 - 2021年03月
  LIM HONGEN, 東京都立大学
  配分額（総額）：4160000, 配分額（直接経費）：3200000, 配分額（間接経費）：960000
  ファンデルワールス物質と固体材料との界面構造への理解は、合成した結晶の構造や成長方向および位置の制御に向けた重要な手がかりとなる。本研究では、化学気相成長法を用いて、そのような接合構造の作製に取り組んできた。主要な成果として、（１）異なる種類の固体界面における遷移金属ダイカルコゲナイド原子層の合成と（２）遷移金属カルコゲナイド原子細線の多量かつ配向制御合成技術を世界に先駆けて確立に成功してきた。
  課題番号：19K15393
• グラフェンナノリボンを原料としたカーボンナノチューブの構造選択的合成　　　　　　　　　　　　　　　
  日本学術振興会, 科学研究費助成事業, 特別研究員奨励費, 2013年04月 - 2015年03月
  リム ホンエン, 名古屋大学, 研究代表者
  配分額（総額）：2400000, 配分額（直接経費）：2400000
  Extended, ultrathin graphene nanoribbons (GNRs) with width of ca. 0.8 nm were successfully prepared inside the carbon nanotube (CNT). This is achieved through vacuum annealing of coronene-filled CNTs at high temperature. Transformation of the precursor molecules into the extended ribbons was confirmed using high resolution transmission electron microscope. Besides, the GNRs fabricated show a lower on-state Raman resonance energy, implying the extension of pi-conjugation. When the outer surface of the CNTs were treated with diazonium salts, an optical band gap of 1.6 eV was observed for the inner GNRs, in good qualitative agreement with the first principles calculations.
  課題番号：13J09322

• 導電膜及び導電部材　　　　　　　　　　　　　　　
  宮田 耕充; 中西 勇介; リム ホンエン; 遠藤 尚彦; 安藤 千里; 清水 宏, 特許権
  特許番号・登録番号：特許第7570659号