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Shuit-Tong Lee

Bio: Shuit-Tong Lee is an academic researcher from Soochow University (Suzhou). The author has contributed to research in topics: Silicon & Nanowire. The author has an hindex of 138, co-authored 1121 publications receiving 77112 citations. Previous affiliations of Shuit-Tong Lee include University of British Columbia & Hong Kong University of Science and Technology.
Topics: Silicon, Nanowire, OLED, Electroluminescence, Diamond


Papers
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Journal ArticleDOI
TL;DR: In this paper, the authors show that the optical emission gaps of hydrogenated silicon nanoparticles are remarkably different and dully dependent on the size for those smaller than 1.5nm, based on their excited-state calculations of a series of nanoparticles from Si5H12 to Si199H140 using a time-dependent tight-binding density functional method.
Abstract: It is well known that the electronic and optical absorption gaps of hydrogenated silicon nanoparticles are inversely proportional to the particle size. Here, the authors show that their optical emission gaps are remarkably different and dully dependent on the size for those smaller than 1.5nm, based on their excited-state calculations of a series of nanoparticles from Si5H12 to Si199H140 using a time-dependent tight-binding density-functional method. It is revealed that this unusual size dependence is due to the strong excited-state structure relaxation in the particle core region that becomes significant when the size decreases.

66 citations

Journal ArticleDOI
TL;DR: In this paper, a chemical vapor deposition process is introduced to prepare silicon (Si)-graphene composite anode materials for lithium-ion batteries, which exhibits high utilization of Si in charge-discharge processes.
Abstract: A chemical vapor deposition process is introduced to prepare silicon (Si)–graphene composite anode materials for lithium-ion batteries. Highly ordered crystalline Si particles are deposited onto graphene sheets by using a liquid chlorosilane as Si source. The Si–graphene composite exhibits high utilization of Si in charge–discharge processes. The capacity retention of 90 % after 500 full cycles and an average Coulombic efficiency in excess of 99.5 % are achieved in half cells. Moreover, atomic layer deposition (ALD) Al2O3 coating is directly applied on the Si-graphene electrode, which greatly suppresses the side reactions between the electrode and electrolyte, resulting in the enhancement in initial Coulombic efficiency and reversible capacity. Finally, a 3.6 V full cell device is demonstrated, which works very well by combining a Si-graphene anode with a Li-excess layer-structured composite Li1.2Ni0.2Mn0.6O2 cathode. This approach is very promising for realizing a high-energy lithium-ion battery.

66 citations

Journal ArticleDOI
TL;DR: In this article, the 1H-pyrazolo[3,4-b]quinoxaline derivatives with N,N-dialkylamino electron-donating groups were prepared; their photoluminescence in solution and electroluminecence in thin-film devices have been investigated.
Abstract: Several new 1H-pyrazolo[3,4-b]quinoxaline derivatives with N,N-dialkylamino electron-donating groups were prepared; their photoluminescence in solution and electroluminescence in thin-film devices have been investigated. They show emission at 520–540 nm with a fluorescence quantum yield close to unity in moderately polar solvents. The absorption and emission maxima shift to red with increasing solvent polarity. The fluorescence quantum yield also increases with increasing solvent polarity from non-polar to moderately polar solvents, then decreases slightly with further increase of solvent polarity. It indicates that both “positive” and “negative” solvatokinetic effects co-exist. The electroluminescence of OLED devices fabricated by using these compounds as dopants was investigated. All devices with the configuration of indium–tin oxide coated glass/NPB (60 nm)/Alq3 : Dopant (30 nm)/Alq3 (20 nm)/Mg : Ag (200 nm) show bright green emission with efficiencies of 7.5–9.7 cd A−1 and narrow full bandwidth at half intensity of 68–75 nm peaking at 536–552 nm.

66 citations

Journal ArticleDOI
TL;DR: In this article, the authors obtained germanium dioxide (GeO2) whiskers in bulk quantity by ablating a target at 820°C with a pulsed KrF excimer laser in an argon atmosphere.
Abstract: We obtained germanium dioxide (GeO2) whiskers in bulk quantity by ablating a germanium target at 820 °C with a pulsed KrF excimer laser in an argon atmosphere. Most of the GeO2 whiskers were smooth and straight with hexagonal or triangular, or quadrilateral cross sections while some of them had a bamboo-shoot-shaped form. Results of scanning electron microscopy, transmission electron microscopy, and x-ray diffraction showed that the whiskers are hexagonal crystalline GeO2.

66 citations

Journal ArticleDOI
TL;DR: In this paper, boron-doped and undoped silicon nanowires (SiNWs) were observed to have clear and regular nanoscale domains on the SiNW surface.
Abstract: Scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) measurements have been performed on boron-doped and undoped silicon nanowires (SiNWs). STM images clearly showed the presence of nanoparticle chains and nanowires in the B-doped SiNWs sample. Clear and regular nanoscale domains were observed on the SiNW surface, which were attributed to boron-induced surface reconstruction. STS measurements have provided current–voltage curves for SiNWs, which showed clearly enhancement in electrical conductivity by boron doping.

66 citations


Cited by
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Journal ArticleDOI
11 Oct 2012-Nature
TL;DR: This work reviews recent progress in graphene research and in the development of production methods, and critically analyse the feasibility of various graphene applications.
Abstract: Recent years have witnessed many breakthroughs in research on graphene (the first two-dimensional atomic crystal) as well as a significant advance in the mass production of this material. This one-atom-thick fabric of carbon uniquely combines extreme mechanical strength, exceptionally high electronic and thermal conductivities, impermeability to gases, as well as many other supreme properties, all of which make it highly attractive for numerous applications. Here we review recent progress in graphene research and in the development of production methods, and critically analyse the feasibility of various graphene applications.

7,987 citations

Journal ArticleDOI
TL;DR: The theoretical charge capacity for silicon nanowire battery electrodes is achieved and maintained a discharge capacity close to 75% of this maximum, with little fading during cycling.
Abstract: There is great interest in developing rechargeable lithium batteries with higher energy capacity and longer cycle life for applications in portable electronic devices, electric vehicles and implantable medical devices. Silicon is an attractive anode material for lithium batteries because it has a low discharge potential and the highest known theoretical charge capacity (4,200 mAh g(-1); ref. 2). Although this is more than ten times higher than existing graphite anodes and much larger than various nitride and oxide materials, silicon anodes have limited applications because silicon's volume changes by 400% upon insertion and extraction of lithium which results in pulverization and capacity fading. Here, we show that silicon nanowire battery electrodes circumvent these issues as they can accommodate large strain without pulverization, provide good electronic contact and conduction, and display short lithium insertion distances. We achieved the theoretical charge capacity for silicon anodes and maintained a discharge capacity close to 75% of this maximum, with little fading during cycling.

6,104 citations

Journal ArticleDOI
09 Mar 2001-Science
TL;DR: The beltlike morphology appears to be a distinctive and common structural characteristic for the family of semiconducting oxides with cations of different valence states and materials of distinct crystallographic structures, which could be an ideal system for fully understanding dimensionally confined transport phenomena in functional oxides.
Abstract: Ultralong beltlike (or ribbonlike) nanostructures (so-called nanobelts) were successfully synthesized for semiconducting oxides of zinc, tin, indium, cadmium, and gallium by simply evaporating the desired commercial metal oxide powders at high temperatures. The as-synthesized oxide nanobelts are pure, structurally uniform, and single crystalline, and most of them are free from defects and dislocations. They have a rectanglelike cross section with typical widths of 30 to 300 nanometers, width-to-thickness ratios of 5 to 10, and lengths of up to a few millimeters. The beltlike morphology appears to be a distinctive and common structural characteristic for the family of semiconducting oxides with cations of different valence states and materials of distinct crystallographic structures. The nanobelts could be an ideal system for fully understanding dimensionally confined transport phenomena in functional oxides and building functional devices along individual nanobelts.

5,677 citations

Journal ArticleDOI
TL;DR: The state of the art, future directions and open questions in Raman spectroscopy of graphene are reviewed, and essential physical processes whose importance has only recently been recognized are described.
Abstract: Raman spectroscopy is an integral part of graphene research. It is used to determine the number and orientation of layers, the quality and types of edge, and the effects of perturbations, such as electric and magnetic fields, strain, doping, disorder and functional groups. This, in turn, provides insight into all sp(2)-bonded carbon allotropes, because graphene is their fundamental building block. Here we review the state of the art, future directions and open questions in Raman spectroscopy of graphene. We describe essential physical processes whose importance has only recently been recognized, such as the various types of resonance at play, and the role of quantum interference. We update all basic concepts and notations, and propose a terminology that is able to describe any result in literature. We finally highlight the potential of Raman spectroscopy for layered materials other than graphene.

5,673 citations

Journal ArticleDOI
TL;DR: This paper presents a meta-analysis of the chiral stationary phase transition of Na6(CO3)(SO4)2, a major component of the response of the immune system to Na2CO3.
Abstract: Ju Mei,†,‡,∥ Nelson L. C. Leung,†,‡,∥ Ryan T. K. Kwok,†,‡ Jacky W. Y. Lam,†,‡ and Ben Zhong Tang*,†,‡,§ †HKUST-Shenzhen Research Institute, Hi-Tech Park, Nanshan, Shenzhen 518057, China ‡Department of Chemistry, HKUST Jockey Club Institute for Advanced Study, Institute of Molecular Functional Materials, Division of Biomedical Engineering, State Key Laboratory of Molecular Neuroscience, Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China Guangdong Innovative Research Team, SCUT-HKUST Joint Research Laboratory, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, China

5,658 citations