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153 results on '"Ju, Sang-Yong"'

4. Scattering Properties of MoS2Edges and Folds Using Darkfield Hyperspectral Microscopy

Author

Bong, Sungmin, Hwang, Seongjoo, and Ju, Sang-Yong

Abstract

The optical characteristics of one-dimensional (1D) MoS2edges and folds at the grain level, acting as interfaces in diverse optoelectronic applications, remain unexplored in contrast to the basal plane. In this study, we utilize dark-field hyperspectral microscopy (DFHM) to investigate the optical properties of individual edges and folds in MoS2synthesized by chemical vapor deposition. Through DFHM, spatiospectral scattering information about these features is acquired. Comparative analysis with complementary reflection hyperspectral microscopy reveals red shifts in transitions on the edge spectrum of single-layered MoS2, regardless of the edge types, attributed to lattice strain and edge defects. Deconvolution of the edge spectrum unveils an increased contribution from the indirect band gap. The polarized DFHM experiment exhibits 1D scattering behavior along edges. An increase in the number of MoS2layers leads to a reduction in the degree of red shift and the intensity of the scatter, correlated with the decreased roughness of the edge surface. Additionally, MoS2folds also exhibited scattering behaviors influenced by the twisted bilayer structure. The DFHM method will be a valuable approach to gain insights into the structure–property relationships at the interfaces of various low-dimensional nanomaterials.

Published
2024
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5. Sorting of Carbon Nanotubes Based on Dispersant Binding Affinities.

Author

Hwang, Seongjoo, Son, Seokhyeon, Park, Minsuk, Choi, In‐Seung, and Ju, Sang‐Yong

Subjects
DISPERSING agents, CARBON nanotubes, RESEARCH personnel, HANDEDNESS, CHIRALITY
Abstract

Sorting single‐walled carbon nanotubes (SWNTs) that are heterogeneous into homogeneous groups based on their electronic type, chirality, and handedness is crucial for optoelectronic and biological applications. To achieve this, researchers have utilized dispersants with different binding affinities to sort SWNTs according to their chiralities. This review article provides an overview of the methods developed for sorting SWNTs using dispersants, with a particular focus on the role played by dispersant binding affinities. The article is organized into six sections, including an introduction, a background on SWNTs and dispersant‐based individualization of SWNTs, information on dispersants and their binding affinities, separation methods for SWNTs based on controlling the dispersant binding affinity, parameters used to control dispersant binding affinity, and a conclusion. It is hoped that this review will enhance understanding of the intricate interactions between dispersants and SWNTs, leading to the development of new SWNT sorting methods for future applications. [ABSTRACT FROM AUTHOR]

Published
2024
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8. Control of Length and Spatial Functionality of Single-Wall Carbon Nanotube AFM Nanoprobes

Author

Wei, Haoyan, Kim, Sang Nyon, Zhao, Minhua, Ju, Sang-Yong, Huey, Bryan D., Marcus, Harris L., and Papadimitrakopoulos, Fotios

Subjects
Condensed Matter - Materials Science
Abstract

Single-wall carbon nanotube (SWNT) nanofibrils were assembled onto conductive atomic force microscopy (AFM) probes with the help of dielectrophoresis (DEP). This process involved the application of a 10 V, 2 MHz, AC bias between a metal-coated AFM probe and a dilute suspension of SWNTs. This exerted a positive dielectrophoretic force onto the nanotubes that caused them to align while precipitating out onto the probe. The gradual removal of the AFM probe away from the SWNT suspension consolidated these nanotubes into nanofibrils with a high degree of alignment as demonstrated with polarization Raman experiments. By varying the pulling speed, immersion time, and concentration of the SWNT suspension, one can tailor the diameter and thus the stiffness of these probes. Precise length trimming of these nanofibrils was also performed by their gradual immersion and dissolution into a liquid that strongly interacted with nanotubes, (i.e., sodium dodecyl sulfate (SDS) solution). Vacuum annealing these nanoprobes at temperature up to 450 degree C further increased their stiffness and rendered them insoluble to SDS and all other aqueous media. Regrowth of a new SWNT nanofibril from the side or at the end of a previously grown SWNT nanofibril was also demonstrated by a repeated dielectrophoretic assembly at the desired immersion depth. These SWNT nanofibril-equipped AFM probes are electrically conductive and mechanically robust for use as high-aspect-ratio electrochemical nanoprobes.

Published
2011
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9. Oxidation resistance of graphene-coated Cu and Cu/Ni alloy

Author

Chen, Shanshan, Brown, Lola, Levendorf, Mark, Cai, Weiwei, Ju, Sang-Yong, Edgeworth, Jonathan, Li, Xuesong, Magnuson, Carl, Velamakanni, Aruna, Piner, Richard R., Park, Jiwoong, and Ruoff, Rodney S.

Subjects
Condensed Matter - Materials Science
Abstract

The ability to protect refined metals from reactive environments is vital to many industrial and academic applications. Current solutions, however, typically introduce several negative effects, including increased thickness and changes in the metal physical properties. In this paper, we demonstrate for the first time the ability of graphene films grown by chemical vapor deposition to protect the surface of the metallic growth substrates of Cu and Cu/Ni alloy from air oxidation. SEM, Raman spectroscopy, and XPS studies show that the metal surface is well protected from oxidation even after heating at 200 \degree C in air for up to 4 hours. Our work further shows that graphene provides effective resistance against hydrogen peroxide. This protection method offers significant advantages and can be used on any metal that catalyzes graphene growth.

Published
2010

12. Electromagnetic interference shielding effects of modified carbon nanotube-nylon 12 composite films.

Author

Lee, Jae Hyuk, Jang, Si-Hoon, Ju, Sang Yong, Kim, Eunkyoung, and Park, No Hyung

Abstract

Metal-based electromagnetic interference shielding materials are limited in their application due to their susceptibility to corrosion. They are therefore being replaced by corrosion-resistant polymers and carbon nanotubes. However, it is difficult to disperse carbon nanotubes within polymer matrices as they aggregate because of van der Waals forces. Therefore, to improve the dispersion of carbon nanotubes, we modified thin-wall carbon nanotubes with flavin mononucleotides and tested them by manufacturing a polymer composite. Nylon 12 was chosen as the polymer matrix owing to its excellent abrasion resistance and low wettability. Furthermore, upon annealing the modified carbon nanotubes, the tensile strength of the composite and dispersion after modification increased. When 10 wt% of the annealed modified nanotubes was used, the composite exhibited a sheet resistance of 8.7 Ω/sq and an EMI shielding effectiveness of 29.4 dB in the X-band. The novel composite can be advantageous for use in electronic equipment due to its low weight and flexibility. [ABSTRACT FROM AUTHOR]

Published
2023
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24. Long-Term Exposure of MoS 2 to Oxygen and Water Promoted Armchair-to-Zigzag-Directional Line Unzippings.

Author

Song, Youngho, Park, Minsuk, Park, Junmo, Ahn, Hyun S., Kim, Tae Kyu, and Ju, Sang-Yong

Subjects
OXYGEN in water, RAMAN spectroscopy, PHOTOLUMINESCENCE, MOLYBDENUM disulfide, NITROGEN
Abstract

Understanding the long-term stability of MoS2 is important for various optoelectronic applications. Herein, we show that the long-term exposure to an oxygen atmosphere for up to a few months results in zigzag (zz)-directional line unzipping of the MoS2 basal plane. In contrast to exposure to dry or humid N2 atmospheres, dry O2 treatment promotes the initial formation of line defects, mainly along the armchair (ac) direction, and humid O2 treatment further promotes ac line unzipping near edges. Further incubation of MoS2 for a few months in an O2 atmosphere results in massive zz-directional line unzipping. The photoluminescence and the strain-doping plot based on two prominent bands in the Raman spectrum show that, in contrast to dry-N2-treated MoS2, the O2-treated MoS2 primarily exhibits hole doping, whereas humid-O2-treated MoS2 mainly exists in a neutral charge state with tension. This study provides a guideline for MoS2 preservation and a further method for generating controlled defects. [ABSTRACT FROM AUTHOR]

Published
2022
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25. Deterministic transfer of thin carbon nanotube film.

Author

Park, Minsuk and Ju, Sang‐Yong

Subjects
*CARBON films, *METHYL methacrylate, *SINGLE walled carbon nanotubes, *CARBON nanotubes, *THIN films, *WATER use, *OPTOELECTRONIC devices
Abstract

Although successfully implemented for optoelectronic devices of two‐dimensional materials, deterministic transfer for thin single‐walled carbon nanotube (SWNT) film has not been realized. Herein, we report a transfer method of few hundreds nanometer‐thick SWNT film to a desired prepatterned substrate position with few micrometer precision. This method comprises poly(methyl methacrylate) (PMMA)‐coated SWNT film, creating surface anisotropy on both sides for SWNT film transfer, and two sets of translators manipulating the film to desired position and angle. Especially, adsorption and desorption of PMMA‐coated SWNT film by each translator were modulated by use of interfacial water which not only promotes PMMA side to the transient sample loader via water capillary and releases the final substrate with capillary assisted sliding. Successful transfer of thin SWNT film with few tens of micrometer precision was achieved and will be beneficial for the preparation of high‐end optoelectronic devices. [ABSTRACT FROM AUTHOR]

Published
2022
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29. Ternary Organic Solar Cells: Performance Optimization of Parallel‐Like Ternary Organic Solar Cells through Simultaneous Improvement in Charge Generation and Transport (Adv. Funct. Mater. 14/2019)

Author

Hadmojo, Wisnu Tantyo, primary, Wibowo, Febrian Tri Adhi, additional, Lee, Wooseop, additional, Jang, Hye‐Kyung, additional, Kim, Yeongsik, additional, Sinaga, Septy, additional, Park, Minsuk, additional, Ju, Sang‐Yong, additional, Ryu, Du Yeol, additional, Jung, In Hwan, additional, and Jang, Sung‐Yeon, additional

Published
2019
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31. Performance Optimization of Parallel‐Like Ternary Organic Solar Cells through Simultaneous Improvement in Charge Generation and Transport

Author

Hadmojo, Wisnu Tantyo, primary, Wibowo, Febrian Tri Adhi, additional, Lee, Wooseop, additional, Jang, Hye‐Kyung, additional, Kim, Yeongsik, additional, Sinaga, Septy, additional, Park, Minsuk, additional, Ju, Sang‐Yong, additional, Ryu, Du Yeol, additional, Jung, In Hwan, additional, and Jang, Sung‐Yeon, additional

Published
2019
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40. Purity rolled up in a tube

Author

Papadimitrakopoulos, Fotios and Ju, Sang-Yong

Subjects
Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Before carbon nanotubes can fulfil their potential in device applications, better ways must be found to produce pure samples of them. A promising approach involves wrapping them up in a [...]

Published
2007

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