• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.171-171
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• 2012

We have studied the effects of plasma treatments on CdS buffer layers in CIGS thin film solar cells. The CdS layers were deposited on CIGS films by chemical bath deposition (CBD) method. The RF plasma treatments of the CdS thin films were performed with Ar, $O_2 and $N_2 gases, respectively. After plasma treatments, the solar cells with Al:ZnO/i-ZnO/CdS/CIGS structures were fabricated. The surface properties of the CdS/CIGS thin films after plasma treatments were investigated with SEM, EDX and AFM measurements. The electrical properties of manufactured solar cell were discussed with the results of current-voltage measurements. The plasma treatments have a strong influence on the open circuit voltage (VOC) and the fill factor of the solar cells. Finally, a correlation between the surface properties of CdS layer and the efficiencies of the CIGS thin film solar cells is discussed.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.347.2-347.2
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• 2016

Recently, in order to improve the performance of the colloidal quantum dot solar cells (CQDSCs), various efforts such as the modification of the cell architecture and surface treatment for quantum dot (QD) passivation have been made. Especially, the incorporation of halides into the QD matrix was reported to improve the performances significantly via passivating QD trap states that lower the life-time of the minority-carrier. In this work, we fabricated a lead sulfide (PbS) QD bilayer treated with different ligands and utilized it as a photoactive layer of the CQDSCs. The bottom and top PbS layer was treated using metal iodide ($MI_x$ and butanedithiol (BuDT), respectively. All the depositions and ligand treatments were carried out in air using layer-by-layer spin-coating process. The fabrication of the active layers as well as the n-type zinc oxide (ZnO) layer was successfully carried out on the bendable indium-tin-oxide (ITO)-coated polyethylene terephthalate (PET) substrate, which implies that this technique can be applied to the fabrication of flexible and/or wearable solar cells. The power conversion efficiency (PCE) of the CQDSCs with the architecture of $PET/ITO/ZnO/PbS-MI_x/PbS-BuDT/MoO_x/Ag$ reached 4.2 %, which is significantly larger than that of the cells with single QD (PbS-BuDT) layer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.4
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• pp.216-220
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• 2018

The piezoelectric properties of $0.65Pb(Zr_{1-x}Ti_x)O_3-0.35Pb(Zn_{1/6}Ni_{1/6}Nb_{2/3})O_3$ ($PZT_x-PZNN$) ceramics with $0.530{\leq}x{\leq}0.555$ were investigated for application to piezoelectric energy harvesters. Although a morphotropic phase boundary (MPB) was found at approximately x = 0.545, the ceramic with the highest figure of merit (FOM) ($d_{33}{\times}g_{33}$) was observed at a composition of x = 0.540. Values of this figure of merit, $d_{33}{\times}g_{33}$, of $19.6pm^2/N$ and $20.2pm^2/N$ were obtained from $PZT_{0.540}-PZNN$ ceramics sintered at $920^{\circ}C$ and $950^{\circ}C$, respectively. A high output power of $937{\mu}W$ and a high power density of $3.3mW/cm^3$ were obtained from unimorph-type piezoelectric energy harvesters fabricated using $PZT_{0.540}-PZNN$ ceramic sintered at $920^{\circ}C$ for 4h.

• Journal of Power System Engineering
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• v.4 no.4
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• pp.99-107
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• 2000

In this study several P type and N type ceramic semiconductors were prepared by atomic valence control and their electric resistivities were investigated with various concentrations of additive impurities. N-P junctions were made by thin film printing method and their varistor-like characteristics were investigated and their availability was discussed. The results are followings, 1) Some N type semiconductors with a proper concentration of additive impurity have minimum resistivities. 2) The N-P junction samples with ZnO as a constituent material of N type semiconductor have linearity in voltage-current characteristics, but the other N-P junction samples have the non-linearity, 3) Some N-P junction samples showed the good varistor-like characteristics.

• Korean Journal of Environmental Agriculture
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• v.22 no.2
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• pp.87-93
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• 2003

Growth and mineral composition of young radish in soil amended with sewage sludge (ISS) with or without liming were investigated. Levels of EC, T-N, and micronutrients were increased in the ISS treatment (50 Mg/ha) compared to the NPK treatment but those of available P and exchangeable cations were decreased. Chlorosis was appear on the young radish leaf at the ISS treatment, but this phytotoxic symptom was corrected with lime amendment (3 Mg/ha). Yields of young radish leaf and root in the combined treatment of ISS and lime were increased about 29 and 48%, respectively, compared with those in the ISS treatment. Contents of P, K, Ca, and Mg in young radish were higher in the combined treatment to ISS and lime, whereas those contents in the ISS treatment were lower than those in the NPK treatment. Contents of Cu, Zn, and Ni in soil and young radish leaf were positively correlated with total N content in young radish leaf, while contents of P, K, Ca, and Mg were negatively correlated. Contents of Cu, Zn, and Ni in leaf were negatively correlated with yield of young radish. Contents of Cu and Zn in leaf corresponding with a 5% yield reduction of young radish were 22.4 and 349 mg/kg, respectively.

• Clean Technology
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• v.27 no.1
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• pp.9-16
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• 2021

Since the active matrix organic light-emitting diode (AMOLED) encapsulation process is very vulnerable to moisture and oxygen, high-purity nitrogen with minimal moisture and oxygen must be used. In this study, a copper-based catalyst used to remove oxygen from nitrogen in the AMOLED encapsulation process was optimized. Two-component and three-component catalysts composed of CuO, Al2O3, or ZnO were prepared through a co-precipitation method. The prepared catalysts were characterized by using BET, XRD, TPR, and XRF analysis. In order to verify the oxygen removal performance of the catalyst, several catalytic reactions were conducted in a fixed bed reactor, and the corresponding oxygen contents were measured through an oxygen analyzer. In addition, reusability of the catalysts was proven through repetitive regeneration. The properties and oxygen removal capacity of the catalysts prepared with CuO and Al2O3 ratios of 6 : 4, 7 : 3, and 8 : 2 were compared. The number of active sites of the catalyst with a ratio of CuO and Al2O3 of 8 : 2 was the highest among the 2-component catalysts. Moreover, the reducibility of the catalyst with a ratio of CuO and Al2O3 of 8 : 2 was the best as it had the highest CuO dispersion. As a result, the oxygen removal ability of the catalyst with a ratio of CuO and Al2O3 of 8 : 2 was the best among the 2-component catalysts. The best oxygen removal capacity was obtained when 2wt% of ZnO was added to the sub-optimized catalyst (i.e., CuO : Al2O3 = 8 : 2) probably due to its outstanding reducibility. Furthermore, the optimized catalyst kept its performance during a couple of regeneration tests.

• Korean Journal of Environmental Agriculture
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• v.19 no.1
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• pp.62-66
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• 2000

This study was conducted to determine the soil chemical properties and microbial flora of platycodon and their effect on rhizome rot incidence. Sampling sites were Keochang 4, Kimhae 7, Haman 6, Chinju 6 and Koseong 3 fields in Kyongnam province and Hongcheong 6 fields in Kangwon province. The root disease incidence rate was in the order of Haman 56.8%, Hongcheon 52.5%, Kimhae 36.7%, Koechang 35.3%, Chinju 32.3%, Koseong 30.0%. The yield at the Chinju 36.17 Mg/ha was higher than that of Koseong 25.00 Mg/ha, Kimhae 13.57 Mg/ha, Koechang 11.75 Mg/ha, Haman 9.50 Mg/ha, Hongcheon 5.24 Mg/ha. The soil K, $NH_4-N$ content and EC value of injury root were higher than those of normal root. The root CaO content was positively correlated with yield $Y=20505X-367.9(R^2=0.129^{\ast})$. The Fe and Zn content of normal root were higher than those of injury root, while the T-N, $P_2O_5$ and $K_2O$ content of normal root were lower than those of injury root. The population of bacteria, actinomycetes and bacteria/fungi ratio increased in soil of normal root, but that of fungi decreased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.11-11
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• 2010

Thin-film-transistors (TFTs) that can be deposited at low temperature have recently attracted lots of applications such as sensors, solar cell and displays, because of the great flexible electronics and transparent. Transparent and flexible transistors are being required that high mobility and large-area uniformity at low temperature [1]. But, unfortunately most of TFT structures are used to be $SiO_2$ as gate dielectric layer. The $SiO_2$ has disadvantaged that it is required to high driving voltage to achieve the same operating efficiency compared with other high-k materials and its thickness is thicker than high-k materials [2]. To solve this problem, we find lots of high-k materials as $HfO_2$, $ZrO_2$, $SiN_x$, $TiO_2$, $Al_2O_3$. Among the High-k materials, $Al_2O_3$ is one of the outstanding materials due to its properties are high dielectric constant ( ~9 ), relatively low leakage current, wide bandgap ( 8.7 eV ) and good device stability. For the realization of flexible displays, all processes should be performed at very low temperatures, but low temperature $Al_2O_3$ grown by sputtering showed deteriorated electrical performance. Further decrease in growth temperature induces a high density of charge traps in the gate oxide/channel. This study investigated the effect of growth temperatures of ALD grown $Al_2O_3$ layers on the TFT device performance. The ALD deposition showed high conformal and defect-free dielectric layers at low temperature compared with other deposition equipments [2]. After ITO was wet-chemically etched with HCl : $HNO_3$ = 3:1, $Al_2O_3$ layer was deposited by ALD at various growth temperatures or lift-off process. Amorphous InGaZnO channel layers were deposited by rf magnetron sputtering at a working pressure of 3 mTorr and $O_2$/Ar (1/29 sccm). The electrodes were formed with electron-beam evaporated Ti (30 nm) and Au (70 nm) bilayer. The TFT devices were heat-treated in a furnace at $300^{\circ}C$ and nitrogen atmosphere for 1 hour by rapid thermal treatment. The electrical properties of the oxide TFTs were measured using semiconductor parameter analyzer (4145B), and LCR meter.

• Bulletin of the Korean Chemical Society
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• v.25 no.10
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• pp.1477-1483
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• 2004

We present the tandem mass spectrometry applications carried out to elucidate the coordination structure of Zn(II) bound lysine ternary complexes, $(Zn+Lys+Lys-H)^+$, which is a good model system to represent a simple (metallo)enzyme-substrate complex (ES). In particular, experimental efforts were focused on revealing the involvement of a lysine side chain ${\varepsilon}$-amino group in the coordination of $Zn^{2+}$ divalent ions. MS/MS fragmentation pattern showed that all the oxygen species within a complex fell off in the form of $H_2O$ in contrast to those of other ternary complexes containing amino acids with simple side chains (4-coordinate geometries, Figure 1a), suggesting that the lysine complexes have different coordination structures from the others. The participation of a lysine basic side chain in the coordination of Zn(II) was experimentally evidenced in MS/MS for $N{\varepsilon}$-Acetyl-L-Lys Zn(II) complexes with acetyl protection groups as well as in MS/MS for the ternary complexes with one $NH_3$ loss, $(Zn+Lys+Lys-NH_3-H)^+$. Detailed structures were predicted using ab initio calculations on $(Zn+Lys+Lys-H)^+$ isomers with 4-, 5-, and 6-coordinate structures. A zwitterionic 4-coordinate complex (Figure 7d) and a 5-coordinate structure with distorted bipyramidal geometry (Figure 7b) are found to be most plausible in terms of energy stability and compatibility with the experimental observations, respectively.

• Bulletin of the Korean Chemical Society
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• v.18 no.2
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• pp.213-217
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• 1997

Magnesium reduction of Mo(N-C6H3-2,6-i-Pr2)2Cl2(DME) in the presence of trimethylphosphine led to a mixture of Mo(N-C6H3-2,6-i-Pr2)(PMe3)2Cl3, 1, and Mo2(PMe3)4Cl4, 2. In solution 1 is slowly air-oxidized to Mo(N-2,6-i-Pr2-C6H3)(OPMe3)(PMe3)Cl3, 3. 1 is chemically inert to carbon nucleophiles (ZnMe2, ZnEt2, AlMe3, AlEt3, LiCp, NaCp, TlCp, NaCp*, MeMgBr, EtMgBr), oxygen nucleophiles (LiOEt, LiO-i-Pr, LiOPh, LiOSPh), and hydrides (LiBEt3H, LiBEt3D). Crystal data for 1: orthorhombic space group P212121, a=11.312(3) Å, b=11.908(3) Å, c=19.381(6) Å, Z=4, R(wR2)=0.0463 (0.1067). Crystal data for 2: monoclinic space group Cc, a=18.384(3) Å, b=9.181(2) Å, c=19.118(3) Å, b=124.98(1)°, Z=4, R(wR2)=0.0228 (0.0568). Crystal data for 3: orthorhombic space group P212121, a=11.464(1) Å, b=14.081(2) Å, c=16.614(3) Å, Z=4, R(wR2)=0.0394 (0.0923).