• Current Photovoltaic Research
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• v.2 no.1
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• pp.18-27
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• 2014

Dye-sensitized solar cells (DSSCs), developed two decades ago, are considered to be an attractive technology among various photovoltaic devices because of their low cost, accessible dye chemistry, ease of fabrication, high power conversion efficiency, and environmentally friendly nature. A typical DSSCs consists of a dye-coated $TiO_2$ photoanode, a redox electrolyte, and a platinum (Pt)-coated fluorine-doped tin oxide (FTO) counter electrode. Among them, redox electrolytes have proven to be extremely important in improving the performance of DSSCs. Due to many drawbacks of iodide electrolytes, many research groups have paid more attention to seeking other alternative electrolyte systems. With regard to this, one-electron outer sphere redox shuttles based on cobalt complexes have shown promising results: In 2014, porphyrin dye (SM315) with the cobalt (II/III) redox couple exhibited a power conversion efficiency of 13% in DSSCs. In this review, we will provide an overview and perspectives of cobalt redox electrolytes in DSSCs.

• Korean Journal of Materials Research
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• v.13 no.11
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• pp.711-716
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• 2003

Gate length, height, and silicide thickness have all been shrinking linearly as device density has progressively increased over the years. We investigated the effect of the cobalt diffusion during the silicide formation process on the 60$\AA$-thick gate oxide lying underneath the Ti/Co and Co/Ti bilayers. We prepared four different cobalt silicides, which have similar sheet resistance, made from the film structure of Co/Ti(interlayer), and Ti(capping layer)/Co, and peformed the current-voltage, time-to-break down, and capacitance-voltage measurements. Our result revealed that the cobalt silicide process without the Ti capping layer allowed cobalt atoms to diffuse into the upper interface of gate oxides. We propose that 100$\AA$-thick titanium interlayer may lessen the diffusion of cobalt to gate oxides in 1500-$\AA$ height polysilicon gates.

• Journal of the Korean institute of surface engineering
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• v.57 no.3
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• pp.140-154
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• 2024

As the trend towards miniaturization in semiconductor integration process, the limitations of interconnection metals such as copper, tungsten have become apparent, prompting research into the emergence of new materials like cobalt and emphasizing the importance of studying the corresponding process conditions. During the chemical mechanical polishing (CMP) process, corrosion inhibitors are added to the slurry, forming passivation layers on the cobalt surface, thereby playing a crucial role in controlling the dissolution rate of the metal surface, enhancing both removal rate and selectivity. This review investigates the understanding of the cobalt polishing process and examines the characteristics and behavior of corrosion inhibitors, a type of slurry additive, on the cobalt surface. Among the corrosion inhibitors examined, benzotriazole (BTA), 1,2,4-triazole (TAZ), and potassium oleate (PO) all improved surface characteristics through their interaction with cobalt. These findings provide important guidelines for selecting corrosion inhibitors to optimize CMP processes for cobalt-based semiconductor materials. Future research should explore combinations of various corrosion inhibitors and the development of new compounds to further enhance the efficiency of semiconductor processes.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.10
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• pp.896-901
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• 2005

The microstructure and electrical properties of praseodymium-based zinc oxide varistors were investigated at various cobalt oxide contents in the range of $0.5{\~}5.0 mol\%$. The ceramic density increased in the range of $5.25{\~}5.55 g/cm^3$ with increasing cobalt oxide content. The varistor doped with cobalt oxide of $1.0 mol\%$ exhibited the highest nonlinearity, with 66.6 in nonlinear exponent and 1.2 $\mu$A in leakage current. The donor concentration, density of interface states, and tamer height were in the range of $(1.06{\~}1.69){\times}10^{18}/cm^3$, $(3.11 {\~}3.56){\times}10^{12}/cm^2$, and 0.80${\~}$1.07 eV, respectively.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1146-1147
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• 2006

Diamond segments were fabricated by cold pressing and sintering under pressure at the temperature up to $750^{\circ}C$. Based on the results of this investigation, it can be concluded that the segments containing 39wt.% cobalt in the matrix material have the highest bending strength at a fracture probability of 50 % due to the weibull distribution method. According to the weibull statistics, it was also determined that the transverse rupture strength was the best for 39 wt.% cobalt ratio in the matrix material for the fracture probability when the other variables are the same.

• The korean journal of orthodontics
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• v.19 no.1 s.27
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• pp.245-256
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• 1989

Translational movement along an arch wire requires sufficient force to overcome frictional forces between bracket and arch wire. The orthodontist must appreciate the importance of friction in this process, and study out the influencing factors on the level of friction. The purpose of this study was to evaluate the effect of artificial saliva on frictional resistances generated between the bracket and arch wire. Independent variables of this study were arch wire material, angulation and environment. Static frictional forces of cobalt-chromium, heat-treated cobalt-chromium, beta-titanium, stainless steel wires were measured under non-angulated dry, angulated dry, non-angulated saliva, angulated saliva conditions. The results were as follows: 1. Stainless steel wires showed lower friction values in non-angulated dry condition, and heat-treated cobalt-chromium wires showed higher friction values in angulated dry condition. Higher friction values were showed in order of cobalt-chromium. stainless steel, heat-treated cobalt-chromium and beta-titanium wires in non-angulated saliva condition. and were showed in order of stainless steel, cobalt-chromium, heat-treated cobalt-chromium, beta-titanium wires in angulated saliva condition. 2. Angulation increased friction for stainless steel wires under dry condition. 3. Artificial saliva decreased friction for cobalt-chromium wires and increased friction for stainless steel wires under non-angulated condition. 4. Artificial saliva decreased friction for all wires except beta-titanium wires under angulated condition. 5. Regardless of angulation or environment. heat-treated cobalt-chromium and beta-titanium wires showed higher friction values, and stainless steel wires showed lower friction values.

• Journal of the Korean Ceramic Society
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• v.45 no.6
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• pp.368-373
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• 2008

An electrode for supercapacitor using 3-dimensional porous nickel foam as a current collector and cobalt oxide as an active material was prepared and characterized in terms of morphology observation, crystalline property analysis, and the investigation of electrochemical property. The electrode surface showed that the cobalt oxide was homogeneously coated as the crystalline phase of $Co_3O_4$. Cyclic voltammetry for the $Co_3O_4$/nickel foam electrode exhibited higher specific capacitance values (445 F/g at 10 mV/s and 350 F/g at 200 mV/s) and excellent capacitance retention ratio (99% after $10^4$ cycles). It was proved that the nickel foam substrate played the roles in reducing the interfacial resistance with cobalt oxide and in improving the electrode density by embedding greater amount of cobalt oxide within it.

• Applied Chemistry for Engineering
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• v.31 no.4
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• pp.423-428
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• 2020

In this work, we investigated the effect of the concentration of medium components on microbial growth and ethanol production in order to improve ethanol productivity in the Clostridium autoethanogenum culture process using syngas as a sole carbon source. Molybenum, nickel and cobalt (as heavy metal ions) were selected as examined components, and the effects of components concentration on the cell growth and ethanol production was examined. Among molybdenum concentrations of 0, 0.001, 0.01 and 0.1 g/L. a slight increase in ethanol production was observed at 0.001 g/L, but significant differences in the microbial growth and ethanol production were not observed in the examined concentration range. In the case of nickel concentration of 0, 0.001, 0.01 and 0.1 g/L, the change in the microbial growth and ethanol production was investigated, and it was found that the ethanol production using 0.001 g/L increased by 26% compared to that of using the basal medium concentration (0.01g/L). The effect of cobalt concentrations (0, 0.018, 0.18 and 1.8 g/L) on the microbial growth and ethanol production was also investigated, and the inhibition of microbial growth was observed when the cobalt usage was over 0.18 g/L. In conclusion, cobalt did not show any further improvement of ethanol production by changing concentration, however, molybdenum and nickel showed increases in the produced ethanol concentration compared to that of using 1/10 times of the basal medium concentration.

• Korean Journal of Metals and Materials
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• v.46 no.4
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• pp.209-216
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• 2008

Super austenitic stainless steels shows the high PRE (Pitting Resistance Equivalent) number and the good corrosion resistance. This work controlled the Co contents in Fe-31Cr-1.7Mo-27Ni-0.25N alloys to elucidate the effect of cobalt contents on the biocompatibility and corrosion resistance. Increasing Co contents, the hardness of the annealed alloys tends to be reduced. In aged alloys, cobalt decreased the increments of hardness by aging treatment. Cobalt decreased the critical pitting temperature (CPT) in 6% $FeCl_3$ + 1% HCl solution, but improved the anodic polarization behavior in Hanks' balanced salt solution and artificial saliva solution. Repassivation rate in artificial body solutions was improved by increasing cobalt contents, but didn't show the linear relationship to PRE number of the alloys. The experimental alloys showed the non-cytotoxicity because of its high corrosion resistance.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3227-3232
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• 2013

A novel Cu-Co-O composite nanocatalyst was designed and prepared for the ozonation of phenol. A synergistic effect of copper and cobalt was observed over the Cu-Co-O composite nanocatalyst, which showed higher activity than either copper or cobalt oxide alone. In addition, the Cu-Co-O composite revealed good activity in a wide initial pH range (4.11-8.05) of water. The fine dispersion of cobalt on the surface of copper oxide boosted the interaction between catalyst and ozone, and the surface Lewis acid sites on the Cu-Co-O composite were determined as the active sites. The Raman spectroscopy also proved that the Cu-Co-O composite was quite sensitive to the ozone. The trivalent cobalt in the Cu-Co-O composite was proposed as the valid state.