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Author

Junsin Yi

Other affiliations: KAERI
Bio: Junsin Yi is an academic researcher from Sungkyunkwan University. The author has contributed to research in topics: Solar cell & Thin film. The author has an hindex of 35, co-authored 531 publications receiving 6431 citations. Previous affiliations of Junsin Yi include KAERI.


Papers
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TL;DR: In this article, aluminum-doped zinc oxide (ZnO:Al), one of the promising TCOs, was prepared by radio frequency (RF) magnetron sputtering on glass (Corning 1737) substrates as a function of the deposition condition Argon gas pressure during deposition was kept in the range 004-133 Pa, and the temperature was maintained in between 300 and 673 K.

144 citations

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TL;DR: In this paper, a large-area multicrystalline silicon (mc-Si) solar cell was fabricated by masking less surface texturing using a SF 6 /O 2 reactive ion etching.

142 citations

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TL;DR: In this paper, the authors focused on the texturing of the silicon surface microstructures by reactive ion etching using a multi-hollow cathode system, which achieved a desirable texturing effect by applying a radiofrequency power of about 20 W per hollow cathode glow.

121 citations

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TL;DR: In this article, a TEM analysis of the ZnO:Sn thin films at various doping levels from 1 to 10.% was performed to verify the grain size of the films.
Abstract: ZnO and Sn doped ZnO (ZnO:Sn) thin films at various doping concentrations from 1 to 10 at.% were prepared by the sol–gel method for an ethanol sensing application. The Sn doping significantly influenced the film growth, grain size and response of the films. The XRD patterns showed that the hexagonal wurtzite structure of the ZnO film was retained even after the Sn doping. The crystallite grain sizes of the ZnO:Sn thin films at 0, 2 and 4 at.% were estimated by using the typical Scherrer's equation. The crystalline quality of the films at 6, 8 and 10 at.% of Sn was degenerated. Typical FESEM images demonstrated the different morphologies for the ZnO:Sn thin films at various Sn concentrations; many pores of various dimensions were observed depending on the doping level. A TEM analysis of the ZnO:Sn thin films at 0, 2 and 4 at.% was performed to verify the grain size. The optimum Sn doping level of ZnO:Sn thin film for ethanol sensing was estimated to be 4 at.%. The 4 at.% sample obtained the highest response to ethanol vapor in the 10–400 ppm level range at a low operating temperature of 250 °C. The sensing mechanism was explained by a variation in the sensitivity model from a neck–grain-boundary controlled sensitivity to a neck-controlled sensitivity. Our work demonstrates the ability to reduce the working temperature as well as to increase the response of ZnO thin film based gas sensors to detect ethanol, which would be of great merit for commercialized applications.

110 citations

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TL;DR: In this article, the authors investigated the biosorption mechanisms of methylene blue (MB) and Cr(III) onto pomelo peel collected from local fruits by combining experimental analysis with ab initio simulations.
Abstract: In this study, the biosorption mechanisms of methylene blue (MB) and Cr(III) onto pomelo peel collected from our local fruits are investigated by combining experimental analysis with ab initio simulations. Factors that affect the adsorption such as pH, adsorption time, adsorbent dosage and initial adsorbate concentration, are fully considered. Five isotherm models—Langmuir, Freundlich, Sips, Temkin, and Dubinin–Radushkevich—are employed to estimate the capacity of pomelo peel adsorption, whereas four kinetic models—pseudo-first-order, pseudo-second-order, Elovich and intra-diffusion models—are also used to investigate the mechanisms of the uptake of MB and Cr(III) onto the pomelo fruit peel. The maximum biosorption capacities calculated from the Langmuir models for MB and Cr(III) at 303 K are, 218.5 mg g−1 and 11.3 mg g−1, respectively. In particular, by combining, for the first time, the experimental FT-IR spectra with those obtained from ab initio calculations, we are able to demonstrate that the primary adsorption mechanisms of the uptake of MB onto pomelo fruit peel are electrostatic attraction and hydrogen-bond formations, whereas the adsorption mechanisms for Cr(III) are electrostatic attraction and n–d interactions.

106 citations


Cited by
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Journal ArticleDOI
Cheng-Xiang Wang1, Longwei Yin, Luyuan Zhang, Dong Xiang, Rui Gao 
15 Mar 2010-Sensors
TL;DR: A brief review of changes of sensitivity of conductometric semiconducting metal oxide gas sensors due to the five factors: chemical components, surface-modification and microstructures of sensing layers, temperature and humidity.
Abstract: Conductometric semiconducting metal oxide gas sensors have been widely used and investigated in the detection of gases. Investigations have indicated that the gas sensing process is strongly related to surface reactions, so one of the important parameters of gas sensors, the sensitivity of the metal oxide based materials, will change with the factors influencing the surface reactions, such as chemical components, surface-modification and microstructures of sensing layers, temperature and humidity. In this brief review, attention will be focused on changes of sensitivity of conductometric semiconducting metal oxide gas sensors due to the five factors mentioned above.

2,122 citations

Journal ArticleDOI
TL;DR: Transparent conductors (TCs) have a multitude of applications for solar energy utilization and for energy savings, especially in buildings as discussed by the authors, which leads naturally to considerations of spectral selectivity, angular selectivity, and temporal variability of TCs, as covered in three subsequent sections.

1,471 citations

Journal ArticleDOI
27 Feb 2012-Sensors
TL;DR: The gas sensing properties of metal oxide nanostructures assembled by nanoparticles are reviewed in this article and the effect of doping is summarized and the perspectives ofMetal oxide gas sensor are given.
Abstract: Metal oxide gas sensors are predominant solid-state gas detecting devices for domestic, commercial and industrial applications, which have many advantages such as low cost, easy production, and compact size However, the performance of such sensors is significantly influenced by the morphology and structure of sensing materials, resulting in a great obstacle for gas sensors based on bulk materials or dense films to achieve highly-sensitive properties Lots of metal oxide nanostructures have been developed to improve the gas sensing properties such as sensitivity, selectivity, response speed, and so on Here, we provide a brief overview of metal oxide nanostructures and their gas sensing properties from the aspects of particle size, morphology and doping When the particle size of metal oxide is close to or less than double thickness of the space-charge layer, the sensitivity of the sensor will increase remarkably, which would be called "small size effect", yet small size of metal oxide nanoparticles will be compactly sintered together during the film coating process which is disadvantage for gas diffusion in them In view of those reasons, nanostructures with many kinds of shapes such as porous nanotubes, porous nanospheres and so on have been investigated, that not only possessed large surface area and relatively mass reactive sites, but also formed relatively loose film structures which is an advantage for gas diffusion Besides, doping is also an effective method to decrease particle size and improve gas sensing properties Therefore, the gas sensing properties of metal oxide nanostructures assembled by nanoparticles are reviewed in this article The effect of doping is also summarized and finally the perspectives of metal oxide gas sensor are given

915 citations