• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2199-2202
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• 2011

The electronic properties of altretamine(2,4,6-tris [dimethylamino]-1,3,5-triazine) adsorbed on epitaxial graphene (EG) were investigated by core-level photoemission spectroscopy (CLPES) in conjunction with low energy electron diffraction (LEED). We found that altretamine molecule adsorbed onto interface layer (S1) of graphene as we confirm decrement of S1 peak using CLPES and haziness of LEED pattern. Moreover, the measured work function changes verified that increased adsorption of the altretamine on graphene layer showed n-type doping characteristics due to charge transfer from altretamine to graphene through the nitrogens. Two distinct nitrogen bonding feature associated with the N 1s peak was clearly observed in the core-level spectra indicating two different chemical environments.

• Carbon letters
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• v.27
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• pp.1-11
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• 2018

A simple, but effective means of tailoring the physical and chemical properties of carbon materials should be secured. In this sense, chemical doping by incorporating boron or nitrogen into carbon materials has been examined as a powerful tool which provides distinctive advantages over exohedral doping. In this paper, we review recent results pertaining methods by which to introduce boron atoms into the $sp^2$ carbon lattice by means of high-temperature thermal diffusion, the properties induced by boron doping, and promising applications of this type of doping. We envisage that intrinsic boron doping will accelerate both scientific and industrial developments in the area of carbon science and technology in the future.

• Bulletin of the Korean Chemical Society
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• v.22 no.11
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• pp.1183-1191
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• 2001

The metallorganic chemical vapor deposition (MOCVD) method has been used to prepare TiO2 thin films for the degradation of hazardous organic compounds, such as 2-chlorophenol (2-CP). The effect of supporting materials and metal doping on the photocatalytic activity of TiO2 thin films also has been studied. TiO2 thin films were coated onto various supporting materials, including stainless steel cloth(SS), quartz glass tube (QGT), and silica gel (SG). Transition metals, such as Pd(II), Pt(IV), Nd(III) and Fe(III), were doped onto TiO2 thin film. The results indicate that Nd(Ⅲ) doping improves the photodegradation of 2-CP. Among all supporting materials studied, SS(37 ${\mu}m)$ appears to be the best support. An optimal amount of doping material at 1.0 percent (w/w) of TiO2-substrate thin film gives the best photodegration of 2-CP.

• Elastomers and Composites
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• v.56 no.4
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• pp.250-253
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• 2021

Polypyrrole is an organic thermoelectric material which has been receiving extensive attention in recent years. Polypyrrole is applicable in various fields because its electrical properties are controllable by its doping concentration. In this study, the effects of the polypyrrole doping state on its photoresponse were investigated. The degree of doping was controlled by ammonia solution treatment. Then, the chemical structure as a function of the doping states was observed by Raman analysis. Moreover, the photocurrent and photovoltage characteristics for various doping states were measured by an asymmetrically irradiated light source. As the degree of doping increased, the electrical conductivity increased, which affected the photocurrent. Meanwhile, the photovoltage was related to the temperature gradient caused by light irradiation.

• Progress in Superconductivity and Cryogenics
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• v.20 no.1
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• pp.28-31
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• 2018

Phase diagrams of electron- and hole-doped $Sr_2VO_3FeAs$ are investigated using Co and Mn substitution at Fe site. Metallic nature survives only for Co (electron) doping, not for Mn (hole) doping. The conductivity of $Sr_2VO_3(Fe,M)As$ (M=Mn,Co) is sensitive to the structural modification of FeAs microstructure rather than carrier doping. This finding implies that the FeAs layer plays a dominant role on the charge conduction, thus the $SrVO_3$ layers should be considered as an insulating block. Also, we found that the superconductivity is rapidly suppressed by both dopants. This result is different from the conventional behavior that superconductivity is induced by doping in the most of Fe pnictides. Our finding strongly supports the uniqueness of $Sr_2VO_3FeAs$ among the Fe pnictide superconductors.

• Journal of the Korean Electrochemical Society
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• v.14 no.2
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• pp.92-97
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• 2011

In this study we have investigated the Li-ion coordination, thermal behavior and electrochemical stability of N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide ($Py_{14}TFSI$) with lithium bis(trifluoromethanesulfony)imide (LiTFSI) doping intended for use as electrolytes for lithium batteries. The ionic conductivity is reduced and glass transition temperature ($T_g$) increases with LiTFSI doping concentration. Also, the electrochemical stability increases with LiTFSI doping. A high LiTFSI doping could enhance the electrochemical stability of electrolytes for lithium batteries, whereas the decrease in the ionic conductivity limits the capacity of the battery.

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2889-2892
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• 2010

The objective of this study was to validate performance characteristics of the Access 2 (Beckman coulter) system for hCG assays for use as a confirmation test for doping control. The Access 2 assay was linear up to 500 IU/L. The correlation coefficient was higher than 0.999, and the sensitivity of the linearity was 0.82. There were no false positive or false negative cases. LOD was 0.59 IU/L. The method was robust when performed by different people. Repeatability and reproducibility were below 7%. We compared reproducibility and recoveries of Access 2 and Elecsys 2010. Access 2 demonstrated higher reproducibility than Elecsys 2010. Recoveries (accuracy) of Access 2 were between 85 and 105%. Recoveries for Elecsys 2010 were between 91 and 104%.

• Journal of the Korean Chemical Society
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• v.63 no.2
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• pp.94-101
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• 2019

Nb, Mo-doped and Nb/Mo-codoped $VO_2(M)$ nanocrystallites with various doping levels were synthesized for the first time by a hydrothermal and post thermal transformation method. The reversible phase transition characteristics of those doped $VO_2(M)$ was comparatively investigated. Nb-doping of $VO_2(M)$ by this method resulted in a very efficient lowering of the transition temperature ($T_c$) with a rate of $-16.7^{\circ}C/at.%$ that is comparable to W-doping, while Mo-doping did not give a serious reduction of $T_c$ with only a rate of $-5.1^{\circ}C/at.%$. Nb/Mo-codoping gave a similar result to Nb-doping without a noticeable difference. The thin films of Nb-doped and Nb/Mo-codoped $VO_2(M)$ with a thickness of ca. 120 nm were prepared by a wet-coating of the nanoparticle-dispersed solutions. Those films showed a good thermochromic modulation of near infrared radiation with 30-35% for Nb-doped $VO_2(M)$ and 37-40% for Nb/Mo-codoped ones. Nb/Mo-codoped $VO_2(M)$ film showed slightly enhanced thermochromic performance compared with Nb-doped $VO_2(M)$ film.

• Bulletin of the Korean Chemical Society
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• v.34 no.7
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• pp.2111-2116
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• 2013

This paper reports substituent effects on the conformational changes in polyaniline (PAni) derivatives. PAni, poly-o-toluidine (POT), and poly-o-anisidine (POA) were formed by potentiodynamic electropolymerization in aqueous solution containing (+)-camphorsulfonic acid (CSA) as a dopant. UV-Vis spectroscopy and cyclic voltammetry measurements revealed that the methyl group showed a greater steric hindrance than the methoxy group. Further, the doping level decreased with increasing steric hindrance. The sign pattern of the circular dichroism (CD) bands for POA was opposite to that for PAni. However, no CD bands were observed in POT. The steric hindrance caused helical inversion, but at a high level of steric hindrance, the helical conformation could not be adopted, because of the reduced doping level. The reduced crystallinity was greatly affected by the decreased doping level. The steric effect influenced the polymer conformation and the doping level, thus determining the optical activity, morphology, and crystallinity of the PAni derivatives.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1411-1414
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• 2007

We have developed a top-emitting white organic electroluminescent device (TWOLED) incorporating a low-reflectivity molybdenum (Mo) anode and doped transport layers as well as a dual-layer architecture of doped blue and yellow emitters with the same blue host. The EL efficiency and operational lifetime of TWOLED can be enhanced by a factor of 1.2 and 3.4 than that of standard TWOLED, respectively, with a co-doping technology in yellow emitter by doping another blue dopant. The enhancement in device performances can be attributed to improve the energy transfer efficiency from blue host to yellow dopant through a blue dopant as medium in yellow emitter.