ORCID Profile
0000-0003-1274-1714
Current Organisation
Yonsei University
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Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1NR04793K
Abstract: Tuning the nanomorphology of group 5 tetradymite M 2 X 3 (where M = Bi and Sb, and X = Se and Te) by going beyond thermodynamic equilibrium.
Publisher: American Chemical Society (ACS)
Date: 09-10-2019
Publisher: Springer Science and Business Media LLC
Date: 04-01-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7NR03377J
Abstract: To build upon the structural ersity in the polymorphic phases of 2D phosphorene, we propose different assembly methods that involve four commonly reported parent phases ( i.e. the α-, β-, γ-, and δ-phosphorene) in combination with the lately reported low-energy one-dimensional defects in α-phosphorene.
Publisher: American Chemical Society (ACS)
Date: 16-03-2018
Publisher: American Chemical Society (ACS)
Date: 24-09-2018
DOI: 10.1021/ACS.JPCLETT.8B02474
Abstract: Experimental verification of optical modulation with external stress has not been easily available in flexible systems. Here, we intentionally induced extra stress in wide band gap ZnO thin films by a unique prestress-driven deposition processing that utilizes a stretching mode. The stretching mode provides homogeneous but biaxial stresses in the hexagonal wurtzite structure, leading to the extension of the c-axis and the contraction of the a-axis. As a result, the reduction of the optical band gap by ∼150 meV was observed for the strain of ∼4.87%. The band gap narrowing was found to occur from the respective downward and upward shifts of the conduction band minimum and valence band maximum under the applied stress. The experimental evidence of optical modulations was supported by the theoretical calculations using density functional theory. The reduced strong interactions between Zn d and O p orbitals were assumed to be responsible for the band gap narrowing.
Publisher: American Chemical Society (ACS)
Date: 06-10-2023
DOI: 10.1021/JACS.3C07768
Publisher: American Chemical Society (ACS)
Date: 08-10-2018
Publisher: American Chemical Society (ACS)
Date: 23-01-2018
DOI: 10.1021/ACS.NANOLETT.7B03897
Abstract: Understanding the mutual interaction between electronic excitations and lattice vibrations is key for understanding electronic transport and optoelectronic phenomena. Dynamic manipulation of such interaction is elusive because it requires varying the material composition on the atomic level. In turn, recent studies on topological insulators (TIs) have revealed the coexistence of a strong phonon resonance and topologically protected Dirac plasmon, both in the terahertz (THz) frequency range. Here, using these intrinsic characteristics of TIs, we demonstrate a new methodology for controlling electron-phonon interaction by lithographically engineered Dirac surface plasmons in the Bi
Publisher: Elsevier BV
Date: 03-2023
Publisher: American Chemical Society (ACS)
Date: 02-02-2018
Publisher: American Chemical Society (ACS)
Date: 02-06-2021
Publisher: American Chemical Society (ACS)
Date: 15-10-2019
Abstract: Strain engineering has been extensively explored for tailoring the material properties and, in turn, improving the device performance of semiconducting thin films. In particular, the effects of strain on the optical properties of these films have attracted considerable research interest, but experimental demonstrations in flexible systems have rarely been reported. Here, we exploited the variable optical properties of flexible ZnS thin films by imposing a controllable external compressive stress during a stretching-driven deposition process. This stress induced crystal anisotropy with an increase in tetragonality, which differs from that of the unstrained cubic ZnS thin films. The refractive index of the films was estimated by means of an envelope method using interference fringes. As a result, the reductions in the refractive index and optical band gap were observed by applying the stretching-driven strains with the resultant compressive stress. The modulated refractive index and its dispersion behavior were further investigated by employing a single-oscillator model to drive subsequent correlative parameters such as dispersion energy, oscillating strength, and high-frequency permittivity. As a proof of concept, an optical lens of ZnS was designed to confirm the effect of in situ stress-mediated optical modulation by detecting the variable focal length with stress.
Publisher: American Chemical Society (ACS)
Date: 17-11-2017
Abstract: Despite the ubiquitous nature of the Peltier effect in low-dimensional thermoelectric devices, the influence of finite temperature on the electronic structure and transport in the Dirac heterointerfaces of the few-layer graphene and layered tetradymite, Sb
Publisher: American Chemical Society (ACS)
Date: 24-12-2018
Abstract: Wetting of the liquid metal on the solid electrolyte of a liquid metal battery controls the operating temperature and performance of the battery. Liquid sodium electrodes are particularly attractive because of their low cost, natural abundance, and geological distribution. However, they wet poorly on a solid electrolyte near its melting temperature, limiting their widespread suitability for low-temperature batteries to be used for large-scale energy storage systems. Herein, we develop an isolated metal-island strategy that can improve sodium wetting in sodium-beta alumina batteries that allows operation at lower temperatures. Our results suggest that in situ heat treatment of a solid electrolyte followed by bismuth deposition effectively eliminates oxygen and moisture from the surface of the solid electrolyte, preventing the formation of an oxide layer on the liquid sodium, leading to enhanced wetting. We also show that employing isolated bismuth islands significantly improves cell performance, with cells retaining 94% of their charge after the initial cycle, an improvement over cells without bismuth islands. These results suggest that coating isolated metal islands is a promising and straightforward strategy for the development of low-temperature sodium-β alumina batteries.
No related grants have been discovered for Woosun Jang.