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Zumpf C, Cacho J, Grasse N, Quinn J, Hampton-Marcell J, Armstrong A, Campbell P, Negri MC, Lee DK. Influence of shrub willow buffers strategically integrated in an Illinois corn-soybean field on soil health and microbial community composition. Sci Total Environ 2021; 772:145674. [PMID: 33663956 DOI: 10.1016/j.scitotenv.2021.145674] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 02/02/2021] [Accepted: 02/02/2021] [Indexed: 06/12/2023]
Abstract
Soil serves many important ecological functions and is an integral part of our existence as a society. However, concerns for soil health are growing globally, in part due to the negative impacts of agricultural management on soil resources. The production of perennial bioenergy crops on marginal land in row-crop production systems is one solution that could improve land-use efficiency and address the sustainability of cropland management. Because the relationship between crop management and the environment is complex, more research is needed to evaluate the potential benefits perennial bioenergy crop production has on soil health, as well as other ecosystem services. In this study, shrub willow buffers were strategically integrated into a corn-soybean cropping system with the main objective of reducing nitrate-N leaching from grain crop production while producing biomass for bioenergy. Two buffer systems (defined by landscape positions) were included for comparison, one on marginal land with exposure to nitrate-N leaching from upslope grain (southern plots) and one on fertile soils with less nitrate-N leaching potential (northern plots). Evaluation of soil (chemistry, bulk density, microbial community) and shrub willow vegetation properties (fine roots, leaf litter decomposition, and nutrient uptake dynamics), showed that landscape position plays an important role in (1) the dynamics of soil chemical properties, (2) shrub willow's influence and productivity, and (3) the provision of additional ecosystem services such as reductions in nitrous oxide emissions and nitrate-N leaching. In addition, the combination of crop type and landscape position (N-grain, N-willow, S-grain, and S-willow) influenced the species composition of the soil microbial community, resulting in unique and identifiable communities. These results highlight the potential application of shrub willow buffers for ecosystem service provision and support of ecosystem processes; however, understanding the relationship between the microbial community, crop type, and landscape is important for understanding the sustainability of the design.
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Affiliation(s)
- Colleen Zumpf
- Argonne National Laboratory, Environmental Science Division, 9700 S. Cass Avenue, Lemont, IL 60439, USA.
| | - Jules Cacho
- Argonne National Laboratory, Environmental Science Division, 9700 S. Cass Avenue, Lemont, IL 60439, USA
| | - Nora Grasse
- Argonne National Laboratory, Environmental Science Division, 9700 S. Cass Avenue, Lemont, IL 60439, USA
| | - John Quinn
- Argonne National Laboratory, Environmental Science Division, 9700 S. Cass Avenue, Lemont, IL 60439, USA
| | - Jarrad Hampton-Marcell
- Argonne National Laboratory, Bioscience Division, 9700 S. Cass Avenue, Lemont, IL 60439, USA
| | - Abigail Armstrong
- Argonne National Laboratory, Environmental Science Division, 9700 S. Cass Avenue, Lemont, IL 60439, USA
| | - Patty Campbell
- Argonne National Laboratory, Environmental Science Division, 9700 S. Cass Avenue, Lemont, IL 60439, USA
| | - M Cristina Negri
- Argonne National Laboratory, Environmental Science Division, 9700 S. Cass Avenue, Lemont, IL 60439, USA
| | - D K Lee
- University of Illinois Urbana-Champaign, Crop Science Department, 1102 S. Goodwin Ave., Urbana, IL, USA
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Meyerov J, Louis M, Lee DK, Fletcher L, Banyasz D, Miles LF, Ma R, Tosif S, Koshy AN, Story DA, Bellomo R, Weinberg L. Associations between preoperative anaemia and hospital costs following major abdominal surgery: cohort study. BJS Open 2021; 5:6218127. [PMID: 33834189 PMCID: PMC8032965 DOI: 10.1093/bjsopen/zraa070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 12/09/2020] [Indexed: 11/28/2022] Open
Abstract
Background Determining the cost-effectiveness and sustainability of patient blood management programmes relies on quantifying the economic burden of preoperative anaemia. This retrospective cohort study aimed to evaluate the hospital costs attributable to preoperative anaemia in patients undergoing major abdominal surgery. Methods Patients who underwent major abdominal surgery between 2010 and 2018 were included. The association between preoperative patient haemoglobin (Hb) concentration and hospital costs was evaluated by curve estimation based on the least-square method. The in-hospital cost of index admission was calculated using an activity-based costing methodology. Multivariable regression analysis and propensity score matching were used to estimate the effects of Hb concentration on variables related directly to hospital costs. Results A total of 1286 patients were included. The median overall cost was US $18 476 (i.q.r.13 784–27 880), and 568 patients (44.2 per cent) had a Hb level below 13.0 g/dl. Patients with a preoperative Hb level below 9.0 g/dl had total hospital costs that were 50.6 (95 per cent c.i. 14.1 to 98.9) per cent higher than those for patients with a preoperative Hb level of 9.0–13.0 g/dl (P < 0.001), 72.5 (30.6 to 128.0) per cent higher than costs for patients with a Hb concentration of 13.1–15.0 g/dl (P < 0.001), and 62.4 (21.8 to 116.7) per cent higher than those for patients with a Hb level greater than 15.0 g/dl (P < 0.001). Multivariable general linear modelling showed that packed red blood cell (PRBC) transfusions were a principal cost driver in patients with a Hb concentration below 9.0 g/dl. Conclusion Patients with the lowest Hb concentration incurred the highest hospital costs, which were strongly associated with increased PRBC transfusions. Costs and possible complications may be decreased by treating preoperative anaemia, particularly more severe anaemia.
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Affiliation(s)
- J Meyerov
- Department of Anaesthesia, Austin Health, Heidelberg, Victoria, Australia
| | - M Louis
- Department of Anaesthesia, Austin Health, Heidelberg, Victoria, Australia
| | - D K Lee
- Department of Anaesthesiology and Pain Medicine, Korea University Guro Hospital, Guro-Gu, Seoul, South Korea
| | - L Fletcher
- Department of Anaesthesia, Austin Health, Heidelberg, Victoria, Australia
| | - D Banyasz
- Department of Anaesthesia, Austin Health, Heidelberg, Victoria, Australia
| | - L F Miles
- Department of Anaesthesia, Austin Health, Heidelberg, Victoria, Australia
| | - R Ma
- Business Intelligence Unit, Austin Health, Heidelberg, Victoria, Australia
| | - S Tosif
- Department of Anaesthesia, Austin Health, Heidelberg, Victoria, Australia
| | - A N Koshy
- Department of Cardiology, Austin Health, Heidelberg, Victoria, Australia
| | - D A Story
- Department of Critical Care, University of Melbourne, Melbourne, Victoria, Australia
| | - R Bellomo
- Department of Critical Care, University of Melbourne, Melbourne, Victoria, Australia.,Department of Intensive Care, Austin Health, Heidelberg, Victoria, Australia.,Data Analytics Research and Evaluation Centre, Austin Hospital and University of Melbourne, Melbourne, Victoria, Australia
| | - L Weinberg
- Department of Anaesthesia, Austin Health, Heidelberg, Victoria, Australia.,Department of Critical Care, University of Melbourne, Melbourne, Victoria, Australia.,University of Melbourne Department of Surgery, Austin Health, Victoria, Australia
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Cho K, Jang J, Park JH, Lee DK, Song S, Kim K, Eo YJ, Yun JH, Gwak J, Chung CH. Optimal CdS Buffer Thickness to Form High-Quality CdS/Cu(In,Ga)Se 2 Junctions in Solar Cells without Plasma Damage and Shunt Paths. ACS Omega 2020; 5:23983-23988. [PMID: 32984719 PMCID: PMC7513370 DOI: 10.1021/acsomega.0c03268] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 08/27/2020] [Indexed: 06/11/2023]
Abstract
CdS has been known to be one of the best junction partners for Cu(In,Ga)Se2 (CIGS) in CIGS solar cells. However, the use of thick CdS buffer decreases the short-circuit current density of CIGS solar cells. There are two obstacles that limit the use of ultrathin CdS. The first is plasma damage to CIGS during the preparation of transparent conducting windows and the second is a low shunt resistance due to the direct contact between the window and CIGS via pinholes in the thin CdS buffer. In other words, to avoid plasma damage and shunt paths, we may have to use a CdS buffer that is thicker than necessary to form a high-quality CdS/CIGS junction. This work aims to determine how thin the CdS buffer can be employed without sacrificing device performance while also eliminating the above two obstacles. We investigate the effect of CdS thickness on the performance of CIGS solar cells with silver nanowire-based window layers, which can eliminate both obstacles. An approximately 13 nm thick CdS buffer allows us to achieve high short-circuit current density and fill factor values. To attain an even high open-circuit voltage, an additional CdS buffer with a thickness of 13 nm is needed. The data from this study imply that an approximately 26 nm thick CdS buffer is sufficient to form a high-quality CdS/CIGS junction.
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Affiliation(s)
- Kyung
Soo Cho
- Department
of Materials and Manufacturing Engineering, Hanbat National University, Daejeon 34158, Republic of Korea
| | - Jiseong Jang
- Department
of Materials and Manufacturing Engineering, Hanbat National University, Daejeon 34158, Republic of Korea
| | - Jeung-Hun Park
- Department
of Chemical and Biological Engineering, and Andlinger Center for Energy
and the Environment, Princeton University, Princeton, New Jersey 08544, United States
| | - Doh-Kwon Lee
- Photoelectronic
Hybrid Research Center, Korea Institute
of Science and Technology, Seoul 02792, Republic
of Korea
| | - Soomin Song
- Photovoltaics
Laboratory, Korea Institute of Energy Research, Daejeon 34129, Republic of Korea
| | - Kihwan Kim
- Photovoltaics
Laboratory, Korea Institute of Energy Research, Daejeon 34129, Republic of Korea
- University
of Science and Technology (UST), Daejeon 34113, Republic
of Korea
| | - Young-Joo Eo
- Photovoltaics
Laboratory, Korea Institute of Energy Research, Daejeon 34129, Republic of Korea
- University
of Science and Technology (UST), Daejeon 34113, Republic
of Korea
| | - Jae Ho Yun
- Photovoltaics
Laboratory, Korea Institute of Energy Research, Daejeon 34129, Republic of Korea
- University
of Science and Technology (UST), Daejeon 34113, Republic
of Korea
| | - Jihye Gwak
- Photovoltaics
Laboratory, Korea Institute of Energy Research, Daejeon 34129, Republic of Korea
- University
of Science and Technology (UST), Daejeon 34113, Republic
of Korea
| | - Choong-Heui Chung
- Department
of Materials and Manufacturing Engineering, Hanbat National University, Daejeon 34158, Republic of Korea
- Department
of Materials Science and Engineering, Hanbat
National University, Daejeon 34158, Republic of Korea
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Lee DK, Kang MS, Cho H. MRI size assessment of cerebral microvasculature using diffusion-time-dependent stimulated-echo acquisition: A feasibility study in rodent. Neuroimage 2020; 215:116784. [PMID: 32276059 DOI: 10.1016/j.neuroimage.2020.116784] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 03/18/2020] [Accepted: 03/21/2020] [Indexed: 11/19/2022] Open
Abstract
In this study, a stimulated-echo (STE) method was employed to robustify the cerebral vessel size estimation near air-tissue, bone-tissue interfaces, and large vessels. The proposed solution is to replace the relaxation rate change from gradient-echo (GRE) with that from STE with long diffusion time after the injection of an intravascular contrast agent, superparamagnetic iron oxide nanoparticles. The corresponding diffusion length of STE is shorter than the length over which the unwanted macroscopic field inhomogeneities but is still longer than the correlation length of the fields induced by small vessels. Therefore, the unwanted field inhomogeneities are refocused, while preserving microscopic susceptibility contrast from cerebral vessels. The mean vessel diameter (dimensionless) derived from the diffusion-time-varying STE method was compared to the mean vessel diameter obtained by a conventional spin-echo (SE) and GRE combination based on Monte-Carlo proton diffusion simulations and in vivo rat experiments at 7 T. The in vivo mean vessel diameter from the MRI experiments was directly compared to available reference mouse brain vasculature obtained by a knife-edge scanning microscope (KESM), which is considered to be the gold standard. Monte-Carlo simulation revealed that SE and GRE-based MR relaxation rate changes (ΔR2 and ΔR2∗, respectively) can be enhanced using single STE-based MR relaxation rate change (ΔRSTE) by regulating diffusion time, especially for small vessels. The in vivo mean vessel diameter from the STE method demonstrated a closer agreement with that from the KESM compared to the combined SE and GRE method, especially in the olfactory bulb and cortex. This study demonstrates that STE relaxation rate changes can be used as consistent measures for assessing small cerebral microvasculature, where macroscopic field inhomogeneity is severe and signal contamination from adjacent large vessels is significant.
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Affiliation(s)
- D K Lee
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - M S Kang
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - H Cho
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, South Korea.
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Lee S, Jang J, Park T, Park YM, Park JS, Kim YK, Lee HK, Jeon EC, Lee DK, Ahn B, Chung CH. Electrodeposited Silver Nanowire Transparent Conducting Electrodes for Thin-Film Solar Cells. ACS Appl Mater Interfaces 2020; 12:6169-6175. [PMID: 31933356 DOI: 10.1021/acsami.9b17168] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Silver nanowire (AgNW) networks have demonstrated high optical and electrical properties, even better than those of indium tin oxide thin films, and are expected to be a next-generation transparent conducting electrode (TCE). Enhanced electrical and optical properties are achieved when the diameter of the AgNWs in the network is fairly small, that is, typically less than 30 nm. However, when AgNWs with such small diameters are used in the network, stability issues arise. One method to resolve the stability issues is to increase the diameter of the AgNWs, but the use of AgNWs with large diameters has the disadvantage of causing a rough surface morphology. In this work, we resolve all of the aforementioned issues with AgNW TCEs by the electrodeposition of Ag onto as-spin-coated thin AgNW TCEs. The electrodeposition of Ag offers many advantages, including the precise adjustment of the AgNW diameter and wire-to-wire welding to improve the junction conductance while minimizing the increase in protrusion height because of the overlap of AgNWs upon increasing the diameter. In addition, Ag electrodeposition on AgNW TCEs can provide higher conductance than that of as-spin-coated AgNW TCEs at the same transparency because of the reduced junction resistance, which generates a superior figure of merit. We applied the electrodeposited (ED) AgNW network to a Cu(In,Ga)Se2 thin-film solar cell and compared the device performance to a device with a standard sputtered transparent conducting oxide (TCO). The cell fabricated by the electrodeposition method showed nearly equal performance to that of a cell with the sputtered TCO. We expect that ED AgNW networks can be used as high-performance and robust TCEs for various optoelectronic applications.
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Affiliation(s)
- Sangyeob Lee
- Department of Materials Science and Engineering , Hanbat National University , Daejeon 34158 , Korea
| | - Jiseong Jang
- Department of Materials Science and Engineering , Hanbat National University , Daejeon 34158 , Korea
| | - Taejun Park
- Department of Materials Science and Engineering , Hanbat National University , Daejeon 34158 , Korea
| | - Young Min Park
- Surface Technology Group , Korea Institute of Industrial Technology , Incheon 21999 , Korea
| | - Joon Sik Park
- Department of Materials Science and Engineering , Hanbat National University , Daejeon 34158 , Korea
| | - Yoon-Kee Kim
- Department of Materials Science and Engineering , Hanbat National University , Daejeon 34158 , Korea
| | - Hyoung-Keun Lee
- Department of Materials Science and Engineering , Hanbat National University , Daejeon 34158 , Korea
| | - Eun-Chae Jeon
- School of Materials Science and Engineering , University of Ulsan , Ulsan 44610 , Korea
| | - Doh-Kwon Lee
- Photoelectronic Hybrid Research Center , Korea Institute of Science and Technology , Seoul 02792 , Korea
| | - Byungmin Ahn
- Department of Materials Science and Engineering and Energy System Research , Ajou University , Suwon 16499 , Korea
| | - Choong-Heui Chung
- Department of Materials Science and Engineering , Hanbat National University , Daejeon 34158 , Korea
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Cheng MH, Dien BS, Lee DK, Singh V. Sugar production from bioenergy sorghum by using pilot scale continuous hydrothermal pretreatment combined with disk refining. Bioresour Technol 2019; 289:121663. [PMID: 31234074 DOI: 10.1016/j.biortech.2019.121663] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 06/14/2019] [Accepted: 06/15/2019] [Indexed: 06/09/2023]
Abstract
Chemical-free pretreatments are attracting increased interest because they generate less inhibitor in hydrolysates. In this study, pilot-scaled continuous hydrothermal (PCH) pretreatment followed by disk refining was evaluated and compared to laboratory-scale batch hot water (LHW) pretreatment. Bioenergy sorghum bagasse (BSB) was pretreated at 160-190 °C for 10 min with and without subsequent disk milling. Hydrothermal pretreatment and disk milling synergistically improved glucose and xylose release by 10-20% compared to hydrothermal pretreatment alone. Maximum yields of glucose and xylose of 82.55% and 70.78%, respectively were achieved, when BSB was pretreated at 190 °C and 180 °C followed by disk milling. LHW pretreated BSB had 5-15% higher sugar yields compared to PCH for all pretreatment conditions. The surface area improvement was also performed. PCH pretreatment combined with disk milling increased BSB surface area by 31.80-106.93%, which was greater than observed using LHW pretreatment.
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Affiliation(s)
- Ming-Hsun Cheng
- Department of Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Bruce S Dien
- Bioenergy Research Unit, National Center for Agricultural Utilization Research, USDA-ARS, Peoria, IL 61604, USA
| | - D K Lee
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Vijay Singh
- Department of Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
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Lee Y, Kim SJ, Kim YS, Kim H, Lee DK, Lee J, Go TH, Cha YS. The usefulness of the SOFA and APACHE II scoring systems for the early prediction of mortality in patients with dapsone poisoning. Hum Exp Toxicol 2018; 38:280-287. [DOI: 10.1177/0960327118806647] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The rate of mortality from dapsone poisoning is high because of the long absorption half-life of dapsone. This study aimed to evaluate the usefulness of the sequential organ failure assessment (SOFA) and acute physiology and chronic health evaluation II (APACHE II) scoring systems for the early prediction of mortality in patients with dapsone poisoning. This is a retrospective and observational study of consecutive patients diagnosed with dapsone poisoning. The SOFA and APACHE II scores were obtained within the first 24 h of admission. Patients were divided into survivor and non-survivor groups. In total, 106 patients were included. The SOFA scores of the survivor and non-survivor groups were 1 (0–8) and 4 (1–10), respectively ( p < 0.001). The APACHE II scores of the survivor and non-survivor groups were 9 (1–25) and 14 (3–23), respectively ( p < 0.001). Based on these scores and in-hospital mortality cases, the standardized mortality ratios for the APACHE II and SOFA were 1.00 (95% confidence interval (CI): 0.64–1.48) and 1.00 (95% CI: 0.64–1.49), respectively. In the model adjusted for clinically important variables and variables with significant differences between the survivor and non-survivor groups, the area under the curve of the SOFA (0.907; 95% CI: 0.834–0.955) was significantly higher than that of the APACHE II (0.793; 95% CI: 0.703–0.867) ( p = 0.008). The SOFA and APACHE II score systems had good discrimination and satisfactory calibration performance in patients with dapsone poisoning. However, the SOFA score was a more useful method in predicting mortality than the APACHE II score.
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Affiliation(s)
- Y Lee
- Department of Emergency Medicine, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - SJ Kim
- Department of Emergency Medicine, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - YS Kim
- Department of Emergency Medicine, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - H Kim
- Department of Emergency Medicine, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - DK Lee
- Department of Emergency Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea
| | - J Lee
- Department of Emergency Medicine, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - TH Go
- Center of Biomedical Data Science, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - YS Cha
- Department of Emergency Medicine, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
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8
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Seo SW, Seo JW, Kim D, Cheon KB, Lee DK, Kim JY. Al-/Ga-Doped ZnO Window Layers for Highly Efficient Cu₂ZnSn(S,Se)₄ Thin Film Solar Cells. J Nanosci Nanotechnol 2018; 18:6437-6441. [PMID: 29677810 DOI: 10.1166/jnn.2018.15674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The successful use of Al-/Ga-doped ZnO (AGZO) thin films as a transparent conducting oxide (TCO) layer of a Cu2ZnSn(S,Se)4 (CZTSSe) thin film solar cell is demonstrated. The AGZO thin films were prepared by radio frequency (RF) sputtering. The structural, crystallographic, electrical, and optical properties of the AGZO thin films were systematically investigated. The photovoltaic properties of CZTSSe thin film solar cells incorporating the AGZO-based TCO layer were also reported. It has been found that the RF power and substrate temperature of the AGZO thin film are important factors determining the electrical, optical, and structural properties. The optimization process involving the RF power and the substrate temperature leads to good electrical and optical transmittance of the AGZO thin films. Finally, the CZTSSe solar cell with the AGZO TCO layer demonstrated a high conversion efficiency of 9.68%, which is higher than that of the conventional AZO counterpart by 12%.
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Affiliation(s)
- Se Won Seo
- Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Korea
| | - Jung Woo Seo
- Green School, Korea University, Seoul 02841, Korea
| | - Donghwan Kim
- Green School, Korea University, Seoul 02841, Korea
| | - Ki-Beom Cheon
- Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Korea
| | - Doh-Kwon Lee
- Green School, Korea University, Seoul 02841, Korea
| | - Jin Young Kim
- Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Korea
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Lee DK, Song YK, Park BW, Cho HP, Yeom JS, Cho G, Cho H. The robustness of T 2 value as a trabecular structural index at multiple spatial resolutions of 7 Tesla MRI. Magn Reson Med 2018; 80:1949-1961. [PMID: 29656389 DOI: 10.1002/mrm.27202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 03/09/2018] [Accepted: 03/11/2018] [Indexed: 12/13/2022]
Abstract
PURPOSE To evaluate the robustness of MR transverse relaxation times of trabecular bone from spin-echo and gradient-echo acquisitions at multiple spatial resolutions of 7 T. METHODS The effects of MRI resolutions to T2 and T2* of trabecular bone were numerically evaluated by Monte Carlo simulations. T2 , T2*, and trabecular structural indices from multislice multi-echo and UTE acquisitions were measured in defatted human distal femoral condyles on a 7 T scanner. Reference structural indices were extracted from high-resolution microcomputed tomography images. For bovine knee trabecular samples with intact bone marrow, T2 and T2* were measured by degrading spatial resolutions on a 7 T system. RESULTS In the defatted trabecular experiment, both T2 and T2* values showed strong ( |r| > 0.80) correlations with trabecular spacing and number, at a high spatial resolution of 125 µm3 . The correlations for MR image-segmentation-derived structural indices were significantly degraded ( |r| < 0.50) at spatial resolutions of 250 and 500 µm3 . The correlations for T2* rapidly dropped ( |r| < 0.50) at a spatial resolution of 500 µm3 , whereas those for T2 remained consistently high ( |r| > 0.85). In the bovine trabecular experiments with intact marrow, low-resolution (approximately 1 mm3 , 2 minutes) T2 values did not shorten ( |r| > 0.95 with respect to approximately 0.4 mm3 , 11 minutes) and maintained consistent correlations ( |r| > 0.70) with respect to trabecular spacing (turbo spin echo, 22.5 minutes). CONCLUSION T2 measurements of trabeculae at 7 T are robust with degrading spatial resolution and may be preferable in assessing trabecular spacing index with reduced scan time, when high-resolution 3D micro-MRI is difficult to obtain.
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Affiliation(s)
- D K Lee
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - Y K Song
- Korea Basic Science Institute, Ochang, South Korea
| | - B W Park
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - H P Cho
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - J S Yeom
- Department of Orthopedic Surgery, Seoul National University, Seoul, South Korea
| | - G Cho
- Korea Basic Science Institute, Ochang, South Korea
| | - H Cho
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, South Korea
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Lee HS, Suk J, Kim H, Kim J, Song J, Jeong DS, Park JK, Kim WM, Lee DK, Choi KJ, Ju BK, Lee TS, Kim I. Enhanced efficiency of crystalline Si solar cells based on kerfless-thin wafers with nanohole arrays. Sci Rep 2018; 8:3504. [PMID: 29472631 PMCID: PMC5823930 DOI: 10.1038/s41598-018-21381-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 01/31/2018] [Indexed: 11/09/2022] Open
Abstract
Several techniques have been proposed for kerfless wafering of thin Si wafers, which is one of the most essential techniques for reducing Si material loss in conventional wafering methods to lower cell cost. Proton induced exfoliation is one of promising kerfless techniques due to the simplicity of the process of implantation and cleaving. However, for application to high efficiency solar cells, it is necessary to cope with some problems such as implantation damage removal and texturing of (111) oriented wafers. This study analyzes the end-of-range defects at both kerfless and donor wafers and ion cutting sites. Thermal treatment and isotropic etching processes allow nearly complete removal of implantation damages in the cleaved-thin wafers. Combining laser interference lithography and a reactive ion etch process, a facile nanoscale texturing process for the kerfless thin wafers of a (111) crystal orientation has been developed. We demonstrate that the introduction of nanohole array textures with an optimal design and complete damage removal lead to an improved efficiency of 15.2% based on the kerfless wafer of a 48 μm thickness using the standard architecture of the Al back surface field.
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Affiliation(s)
- Hyeon-Seung Lee
- Center for Electronic Materials, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea.,School of Electrical Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Jaekwon Suk
- Advanced Analysis Center, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Hyeyeon Kim
- Advanced Analysis Center, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Joonkon Kim
- Advanced Analysis Center, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Jonghan Song
- Advanced Analysis Center, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Doo Seok Jeong
- Center for Electronic Materials, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Jong-Keuk Park
- Center for Electronic Materials, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Won Mok Kim
- Center for Electronic Materials, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Doh-Kwon Lee
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Kyoung Jin Choi
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, South Korea
| | - Byeong-Kwon Ju
- School of Electrical Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Taek Sung Lee
- Center for Electronic Materials, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Inho Kim
- Center for Electronic Materials, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea.
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11
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Lee MS, Anderson EK, Stojšin D, McPherson MA, Baltazar B, Horak MJ, de la Fuente JM, Wu K, Crowley JH, Rayburn AL, Lee DK. Assessment of the potential for gene flow from transgenic maize (Zea mays L.) to eastern gamagrass (Tripsacum dactyloides L.). Transgenic Res 2017; 26:501-514. [PMID: 28466411 PMCID: PMC5504203 DOI: 10.1007/s11248-017-0020-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 04/24/2017] [Indexed: 10/24/2022]
Abstract
Eastern gamagrass (Tripsacum dactyloides L.) belongs to the same tribe of the Poaceae family as maize (Zea mays L.) and grows naturally in the same region where maize is commercially produced in the USA. Although no evidence exists of gene flow from maize to eastern gamagrass in nature, experimental crosses between the two species were produced using specific techniques. As part of environmental risk assessment, the possibility of transgene flow from maize to eastern gamagrass populations in nature was evaluated with the objectives: (1) to assess the seeds of eastern gamagrass populations naturally growing near commercial maize fields for the presence of a transgenic glyphosate-tolerance gene (cp4 epsps) that would indicate cross-pollination between the two species, and (2) to evaluate the possibility of interspecific hybridization between transgenic maize used as male parent and eastern gamagrass used as female parent. A total of 46,643 seeds from 54 eastern gamagrass populations collected in proximity of maize fields in Illinois, USA were planted in a field in 2014 and 2015. Emerged seedlings were treated with glyphosate herbicide and assessed for survival. An additional 48,000 seeds from the same 54 eastern gamagrass populations were tested for the presence of the cp4 epsps transgene markers using TaqMan® PCR method. The results from these trials showed that no seedlings survived the herbicide treatment and no seed indicated presence of the herbicide tolerant cp4 epsps transgene, even though these eastern gamagrass populations were exposed to glyphosate-tolerant maize pollen for years. Furthermore, no interspecific hybrid seeds were produced from 135 hand-pollination attempts involving 1529 eastern gamagrass spikelets exposed to maize pollen. Together, these results indicate that there is no evidence of gene flow from maize to eastern gamagrass in natural habitats. The outcome of this study should be taken in consideration when assessing for environmental risks regarding the consequence of gene flow from transgenic maize to its wild relatives.
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Affiliation(s)
- Moon-Sub Lee
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1102 S. Goodwin Ave., Urbana, IL, 61801, USA
| | - Eric K Anderson
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1102 S. Goodwin Ave., Urbana, IL, 61801, USA
| | - Duška Stojšin
- Monsanto Company, 800 North Lindbergh Blvd., St. Louis, MO, 63167, USA
| | - Marc A McPherson
- Monsanto Company, 800 North Lindbergh Blvd., St. Louis, MO, 63167, USA
| | - Baltazar Baltazar
- Monsanto Company, 800 North Lindbergh Blvd., St. Louis, MO, 63167, USA
| | - Michael J Horak
- Monsanto Company, 800 North Lindbergh Blvd., St. Louis, MO, 63167, USA
| | - Juan Manuel de la Fuente
- Monsanto Company, Park Plaza Torre II, 504 Javier Barros Sierra Ave., Col. Santa Fe, Del. Alvaro Obregon, CP 01210, Mexico, DF, Mexico
| | - Kunsheng Wu
- Monsanto Company, 700 Chesterfield Parkway W., St. Louis, MO, 63017, USA
| | - James H Crowley
- Monsanto Company, 700 Chesterfield Parkway W., St. Louis, MO, 63017, USA
| | - A Lane Rayburn
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1102 S. Goodwin Ave., Urbana, IL, 61801, USA
| | - D K Lee
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1102 S. Goodwin Ave., Urbana, IL, 61801, USA.
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12
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Bishop JW, Kim S, Villamil MB, Lee DK, Rayburn AL. Meiotic pairing as an indicator of genome composition in polyploid prairie cordgrass (Spartina pectinata Link). Genetica 2017; 145:235-240. [PMID: 28243829 DOI: 10.1007/s10709-017-9955-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 01/31/2017] [Indexed: 11/27/2022]
Abstract
The existence of neopolyploidy in prairie cordgrass (Spartina pectinata Link) has been documented. The neohexaploid was discovered coexisting with tetraploids in central Illinois, and has been reported to exhibit competitiveness in the natural environment. It is hypothesized that the natural tetraploid cytotype produced the hexaploid cytotype via production of unreduced gametes. Meiosis I chromosome pairing was observed in tetraploid (2n = 4x = 40), hexaploid (2n = 6x = 60), and octoploid (2n = 8x = 80) accessions and the percentage of meiotic abnormality was determined. Significant differences in meiotic abnormality exist between tetraploid, hexaploid, and octoploid cytotypes. An elevated incidence of abnormal, predominantly trivalent pairing in the neohexaploid suggests that it may possess homologous chromosomes in sets of three, in contrast to the tetraploid and octoploid cytotypes, which likely possess homologous chromosomes in sets of two. Abnormal chromosome pairing in the hexaploid may result in unequal allocation of chromosomes to daughter cells during later stages of meiosis. Chromosome pairing patterns in tetraploid, hexaploid, and octoploid cytotypes indicate genome compositions of AABB, AAABBB, and AABBA'A'B'B', respectively.
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Affiliation(s)
- Jeffrey W Bishop
- Department of Crop Sciences, University of Illinois, 1102 S. Goodwin Ave, Urbana, IL, 61801, USA
| | - Sumin Kim
- Department of Crop Sciences, University of Illinois, 1102 S. Goodwin Ave, Urbana, IL, 61801, USA
| | - María B Villamil
- Department of Crop Sciences, University of Illinois, 1102 S. Goodwin Ave, Urbana, IL, 61801, USA
| | - D K Lee
- Department of Crop Sciences, University of Illinois, 1102 S. Goodwin Ave, Urbana, IL, 61801, USA
| | - A Lane Rayburn
- Department of Crop Sciences, University of Illinois, 1102 S. Goodwin Ave, Urbana, IL, 61801, USA.
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13
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Lee BS, Park SYL, Lee JM, Jeong JH, Kim JY, Chung CH, Lee DK. Suppressed Formation of Conductive Phases in One-Pot Electrodeposited CuInSe2 by Tuning Se Concentration in Aqueous Electrolyte. ACS Appl Mater Interfaces 2016; 8:24585-24593. [PMID: 27585315 DOI: 10.1021/acsami.6b07065] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The single-bath electrochemical deposition of CuInSe2 often leads to short-circuit behavior of the resulting solar cells due to the high shunt conductance. In this study, in an attempt to resolve this problem, the influence of the Se precursor concentration (CSe) on electrodeposited CuInSe2 films and solar cell devices is examined in the CSe range of 4.8 to 12.0 mM in selenite-based aqueous solutions containing Cu and In chlorides along with sulfamic acid (H3NSO3) and potassium hydrogen phthalate (C8H5KO4) additives. As CSe increases, the CuInSe2 layers become porous, and the grain growth of the CuInSe2 phase is restricted, while the parasitic shunting problem was markedly alleviated, as unambiguously demonstrated by measurements of the local current distribution. Due to these ambivalent influences, an optimal value of CSe that achieves the best quality of the films for high-efficiency solar cells is identified. Thus, the device prepared with 5.2 mM Se exhibits a power-conversion efficiency exceeding 10% with greatly improved device parameters, such as the shunt conductance and the reverse saturation current. The rationale of the present approach along with the physicochemical origin of its conspicuous impact on the resulting devices is discussed in conjunction with the electro-crystallization mechanism of the CuInSe2 compound.
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Affiliation(s)
- Byung-Seok Lee
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST) , Seoul 136-791, Korea
- Nanomaterials Science and Engineering, Korea University of Science and Technology , Daejeon 305-350, Korea
| | - Sung-Yul L Park
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST) , Seoul 136-791, Korea
- Nanomaterials Science and Engineering, Korea University of Science and Technology , Daejeon 305-350, Korea
| | - Jang Mi Lee
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST) , Seoul 136-791, Korea
- Nanomaterials Science and Engineering, Korea University of Science and Technology , Daejeon 305-350, Korea
| | - Jeung-Hyun Jeong
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST) , Seoul 136-791, Korea
| | - Jin Young Kim
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST) , Seoul 136-791, Korea
| | - Choong-Heui Chung
- Department of Material Sciences and Engineering, Hanbat National University , Daejeon 305-719, Korea
| | - Doh-Kwon Lee
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST) , Seoul 136-791, Korea
- Nanomaterials Science and Engineering, Korea University of Science and Technology , Daejeon 305-350, Korea
- Green School, Korea University , Seoul 136-713, Korea
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14
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Jung HS, Jin SH, Cho JH, Han SH, Lee DK, Cho H. UTE-ΔR2 -ΔR2 * combined MR whole-brain angiogram using dual-contrast superparamagnetic iron oxide nanoparticles. NMR Biomed 2016; 29:690-701. [PMID: 27061076 DOI: 10.1002/nbm.3514] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2015] [Revised: 02/10/2016] [Accepted: 02/19/2016] [Indexed: 06/05/2023]
Abstract
The ability to visualize whole-brain vasculature is important for quantitative in vivo investigation of vascular malfunctions in cerebral small vessel diseases, including cancer, stroke and neurodegeneration. Transverse relaxation-based ΔR2 and ΔR2 * MR angiography (MRA) provides improved vessel-tissue contrast in animal deep brain with the aid of intravascular contrast agents; however, it is susceptible to orientation dependence, air-tissue interface artifacts and vessel size overestimation. Dual-mode MRA acquisition with superparamagnetic iron oxide nanoparticles (SPION) provides a unique opportunity to systematically compare and synergistically combine both longitudinal (R1 ) and transverse (ΔR2 and ΔR2 *) relaxation-based MRA. Through Monte Carlo (MC) simulation and MRA experiments in normal and tumor-bearing animals with intravascular SPION, we show that ultrashort TE (UTE) MRA acquires well-defined vascularization on the brain surface, minimizing air-tissue artifacts, and combined ΔR2 and ΔR2 * MRA simultaneously improves the sensitivity to intracortical penetrating vessels and reduces vessel size overestimation. Consequently, UTE-ΔR2 -ΔR2 * combined MRA complements the shortcomings of individual angiograms and provides a strategy to synergistically merge longitudinal and transverse relaxation effects to generate more robust in vivo whole-brain micro-MRA. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- H S Jung
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - S H Jin
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - J H Cho
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - S H Han
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - D K Lee
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - H Cho
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan, South Korea
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15
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Seo SW, Jeon JO, Seo JW, Yu YY, Jeong JH, Lee DK, Kim H, Ko MJ, Son HJ, Jang HW, Kim JY. Compositional and Interfacial Modification of Cu2 ZnSn(S,Se)4 Thin-Film Solar Cells Prepared by Electrochemical Deposition. ChemSusChem 2016; 9:439-444. [PMID: 26822494 DOI: 10.1002/cssc.201501256] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 12/24/2015] [Indexed: 06/05/2023]
Abstract
A highly efficient Cu2 ZnSn(S,Se)4 (CZTSSe)-based thin-film solar cell (9.9%) was prepared using an electrochemical deposition method followed by thermal annealing. The Cu-Zn-Sn alloy films was grown on a Mo-coated glass substrate using a one-pot electrochemical deposition process, and the metallic precursor films was annealed under a mixed atmosphere of S and Se to form CZTSSe thin films with bandgap energies ranging from 1.0 to 1.2 eV. The compositional modification of the S/(S+Se) ratio shows a trade-off effect between the photocurrent and photovoltage, resulting in an optimum bandgap of roughly 1.14 eV. In addition, the increased S content near the p-n junction reduces the dark current and interface recombination, resulting in a further enhancement of the open-circuit voltage. As a result of the compositional and interfacial modification, the best CZTSSe-based thin-film solar cell exhibits a conversion efficiency of 9.9%, which is among the highest efficiencies reported so far for electrochemically deposited CZTSSe-based thin-film solar cells.
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Affiliation(s)
- Se Won Seo
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Seoul, 02792, South Korea
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, South Korea
| | - Jong-Ok Jeon
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Seoul, 02792, South Korea
- Department of Nanomaterials Science and Engineering, University of Science and Technology, Daejeon, 34113, South Korea
| | - Jung Woo Seo
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Seoul, 02792, South Korea
- Green School, Korea University, Seoul, 136-701, South Korea
| | - Yi Yin Yu
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Seoul, 02792, South Korea
| | - Jeung-Hyun Jeong
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Seoul, 02792, South Korea
| | - Doh-Kwon Lee
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Seoul, 02792, South Korea
- Green School, Korea University, Seoul, 136-701, South Korea
| | - Honggon Kim
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Seoul, 02792, South Korea
| | - Min Jae Ko
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Seoul, 02792, South Korea
- KU-KIST Graduate School of Convering Science and Technology, Korea University, Seoul, 136-701, South Korea
| | - Hae Jung Son
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Seoul, 02792, South Korea
| | - Ho Won Jang
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, South Korea
| | - Jin Young Kim
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, South Korea.
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16
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Friesen PC, Peixoto MDM, Lee DK, Sage RF. Sub-zero cold tolerance of Spartina pectinata (prairie cordgrass) and Miscanthus × giganteus: candidate bioenergy crops for cool temperate climates. J Exp Bot 2015; 66:4403-13. [PMID: 25873680 PMCID: PMC4493780 DOI: 10.1093/jxb/erv085] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Miscanthus × giganteus grown in cool temperate regions of North America and Europe can exhibit severe mortality in the year after planting, and poor frost tolerance of leaves. Spartina pectinata (prairie cordgrass), a productive C4 perennial grass native to North America, has been suggested as an alternative biofuel feedstock for colder regions; however, its cold tolerance relative to M. × giganteus is uncertain. Here, we compare the cold tolerance thresholds for winter-dormant rhizomes and spring/summer leaves of M. × giganteus and three accessions of S. pectinata. All genotypes were planted at a field site in Ontario, Canada. In November and February, the temperatures corresponding to 50% rhizome mortality (LT(50)) were near -24°C for S. pectinata and -4°C for M. × giganteus. In late April, the LT50 of rhizomes rose to -10°C for S. pectinata but remained near -4°C for M. × giganteus. Twenty percent of the M. × giganteus rhizomes collected in late April were dead while S. pectinata rhizomes showed no signs of winter injury. Photosynthesis and electrolyte leakage measurements in spring and summer demonstrate that S. pectinata leaves have greater frost tolerance in the field. For example, S. pectinata leaves remained viable above -9°C while the mortality threshold was near -5°C for M. × giganteus. These results indicate M. × giganteus will be unsuitable for production in continental interiors of cool-temperate climate zones unless freezing and frost tolerance are improved. By contrast, S. pectinata has the freezing and frost tolerance required for a higher-latitude bioenergy crop.
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Affiliation(s)
- Patrick C Friesen
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada, M5S 3B2
| | - Murilo de Melo Peixoto
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada, M5S 3B2
| | - D K Lee
- Department of Crop Sciences, University of Illinois, 1102 S. Goodwin Ave, Urbana, IL 61801, USA
| | - Rowan F Sage
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada, M5S 3B2
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17
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Yu JC, Kim DB, Baek G, Lee BR, Jung ED, Lee S, Chu JH, Lee DK, Choi KJ, Cho S, Song MH. High-Performance Planar Perovskite Optoelectronic Devices: A Morphological and Interfacial Control by Polar Solvent Treatment. Adv Mater 2015; 27:3492-3500. [PMID: 25939990 DOI: 10.1002/adma.201500465] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 03/27/2015] [Indexed: 06/04/2023]
Abstract
Highly efficient planar perovskite optoelectronic devices are realized by amine-based solvent treatment on compact TiO2 and by optimizing the morphology of the perovskite layers. Amine-based solvent treatment between the TiO2 and the perovskite layers enhances electron injection and extraction and reduces the recombination of photogenerated charges at the interface.
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Affiliation(s)
- Jae Choul Yu
- School of Materials Science Engineering and KIST-UNIST Ulsan Center for Convergent, Materials Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan, 689-798, Republic of Korea
| | - Da Bin Kim
- School of Materials Science Engineering and KIST-UNIST Ulsan Center for Convergent, Materials Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan, 689-798, Republic of Korea
| | - Gyoelim Baek
- Departmat of Physics and EHSRC, University of Ulsan, Ulsan, 680-749, Republic of Korea
| | - Bo Ram Lee
- School of Materials Science Engineering and KIST-UNIST Ulsan Center for Convergent, Materials Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan, 689-798, Republic of Korea
| | - Eui Dae Jung
- School of Materials Science Engineering and KIST-UNIST Ulsan Center for Convergent, Materials Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan, 689-798, Republic of Korea
| | - Seungjin Lee
- School of Materials Science Engineering and KIST-UNIST Ulsan Center for Convergent, Materials Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan, 689-798, Republic of Korea
| | - Jae Hwan Chu
- School of Materials Science Engineering, Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan, 689-798, Republic of Korea
| | - Doh-Kwon Lee
- Photo-electronic Hybrids Research Center and KIST-UNIST Ulsan Center for Convergent Materials, Korea Institute of Science and Technology (KIST), Seoul, 136-791, Republic of Korea
| | - Kyoung Jin Choi
- School of Materials Science Engineering and KIST-UNIST Ulsan Center for Convergent, Materials Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan, 689-798, Republic of Korea
| | - Shinuk Cho
- Departmat of Physics and EHSRC, University of Ulsan, Ulsan, 680-749, Republic of Korea
| | - Myoung Hoon Song
- School of Materials Science Engineering and KIST-UNIST Ulsan Center for Convergent, Materials Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan, 689-798, Republic of Korea
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18
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Kim SM, Guo J, Kwak S, Jin YS, Lee DK, Singh V. Effects of genetic variation and growing condition of prairie cordgrass on feedstock composition and ethanol yield. Bioresour Technol 2015; 183:70-77. [PMID: 25723129 DOI: 10.1016/j.biortech.2015.02.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 02/06/2015] [Accepted: 02/07/2015] [Indexed: 06/04/2023]
Abstract
Prairie cordgrass (Spartina pectinata L.) has the potential to be a feedstock for bioethanol. It is native to North America, and has extensive genetic diversity. Eleven natural populations of prairie cordgrass harvested in 2011 and 2012 were studied. Compositions of the samples showed significant differences within the same year, and between the two years. Two highest, one medium and two lowest glucan concentration samples from each year were selected to evaluate ethanol yield after dilute acid pretreatment and simultaneous saccharification and co-fermentation using Saccharomycescerevisiae SR8 that can ferment both glucose and xylose. Up to 88% of theoretical ethanol yields were achieved. Our research demonstrates the potential of prairie cordgrass as a dedicated energy crop with ethanol yields of 205.0-275.6 g/kg biomass and 1748-4368 L/ha, depending on feedstock composition and biomass yield. These ethanol yields are comparable with those of switchgrass, corn stover and bagasse.
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Affiliation(s)
- Sun Min Kim
- Department of Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, 1304 West Pennsylvania Avenue, Urbana, IL 61801, United States
| | - Jia Guo
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1102 South Goodwin Avenue, Urbana, IL 61801, United States
| | - Suryang Kwak
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, 905 South Goodwin Avenue, Urbana, IL 61801, United States
| | - Yong-Su Jin
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, 905 South Goodwin Avenue, Urbana, IL 61801, United States; Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 West Gregory Drive, Urbana, IL 61801, United States
| | - D K Lee
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1102 South Goodwin Avenue, Urbana, IL 61801, United States
| | - Vijay Singh
- Department of Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, 1304 West Pennsylvania Avenue, Urbana, IL 61801, United States.
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Yoo K, Kim JY, Lee JA, Kim JS, Lee DK, Kim K, Kim JY, Kim B, Kim H, Kim WM, Kim JH, Ko MJ. Completely transparent conducting oxide-free and flexible dye-sensitized solar cells fabricated on plastic substrates. ACS Nano 2015; 9:3760-3771. [PMID: 25769343 DOI: 10.1021/acsnano.5b01346] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
To achieve commercialization and widespread application of next-generation photovoltaics, it is important to develop flexible and cost-effective devices. Given this, the elimination of expensive transparent conducting oxides (TCO) and replacement of conventional glass substrates with flexible plastic substrates presents a viable strategy to realize extremely low-cost photovoltaics with a potentially wide applicability. To this end, we report a completely TCO-free and flexible dye-sensitized solar cell (DSSC) fabricated on a plastic substrate using a unique transfer method and back-contact architecture. By adopting unique transfer techniques, the working and counter electrodes were fabricated by transferring high-temperature-annealed TiO2 and Pt/carbon films, respectively, onto flexible plastic substrates without any exfoliation. The fabricated working electrode with the conventional counter electrode exhibited a record efficiency for flexible DSSCs of 8.10%, despite its TCO-free structure. In addition, the completely TCO-free and flexible DSSC exhibited a remarkable efficiency of 7.27%. Furthermore, by using an organic hole-transporting material (spiro-MeOTAD) with the same transfer method, solid-state flexible TCO-free DSSCs were also successfully fabricated, yielding a promising efficiency of 3.36%.
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Affiliation(s)
- Kicheon Yoo
- ‡Department of Chemical and Biomolecular Engineering, Yonsei University, Seoul, 120-746, Republic of Korea
| | | | | | | | | | | | | | | | | | | | - Jong Hak Kim
- ‡Department of Chemical and Biomolecular Engineering, Yonsei University, Seoul, 120-746, Republic of Korea
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20
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Lee MW, Kim JY, Son HJ, Kim JY, Kim B, Kim H, Lee DK, Kim K, Lee DH, Ko MJ. Tailoring of energy levels in D-π-A organic dyes via fluorination of acceptor units for efficient dye-sensitized solar cells. Sci Rep 2015; 5:7711. [PMID: 25591722 PMCID: PMC4296309 DOI: 10.1038/srep07711] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 12/01/2014] [Indexed: 11/11/2022] Open
Abstract
A molecular design is presented for tailoring the energy levels in D-π-A organic dyes through fluorination of their acceptor units, which is aimed at achieving efficient dye-sensitized solar cells (DSSCs). This is achieved by exploiting the chemical structure of common D-π-A organic dyes and incorporating one or two fluorine atoms at the ortho-positions of the cyanoacetic acid as additional acceptor units. As the number of incorporated fluorine atoms increases, the LUMO energy level of the organic dye is gradually lowered due to the electron-withdrawing effect of fluorine, which ultimately results in a gradual reduction of the HOMO-LUMO energy gap and an improvement in the spectral response. Systematic investigation of the effects of incorporating fluorine on the photovoltaic properties of DSSCs reveals an upshift in the conduction-band potential of the TiO2 electrode during impedance analysis; however, the incorporation of fluorine also results in an increased electron recombination rate, leading to a decrease in the open-circuit voltage (Voc). Despite this limitation, the conversion efficiency is gradually enhanced as the number of incorporated fluorine atoms is increased, which is attributed to the highly improved spectral response and photocurrent.
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Affiliation(s)
- Min-Woo Lee
- 1] Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology, Seoul, 136-791, Korea [2] Department of Chemistry, Sogang University, Seoul, 121-742, Korea
| | - Jae-Yup Kim
- Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology, Seoul, 136-791, Korea
| | - Hae Jung Son
- Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology, Seoul, 136-791, Korea
| | - Jin Young Kim
- 1] Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology, Seoul, 136-791, Korea [2] Green School, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul 136-701, Korea
| | - BongSoo Kim
- 1] Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology, Seoul, 136-791, Korea [2] Green School, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul 136-701, Korea
| | - Honggon Kim
- 1] Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology, Seoul, 136-791, Korea [2] Green School, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul 136-701, Korea
| | - Doh-Kwon Lee
- Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology, Seoul, 136-791, Korea
| | - Kyungkon Kim
- Department Chemistry and Nano Science, Ewha Womans University, Seoul, 120-750, Korea
| | - Duck-Hyung Lee
- Department of Chemistry, Sogang University, Seoul, 121-742, Korea
| | - Min Jae Ko
- 1] Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology, Seoul, 136-791, Korea [2] Green School, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul 136-701, Korea
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21
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Park S, Seo D, Ryu TI, Ahn G, Kwak K, Kim H, Cheon CH, Park NG, Kim B, Ko MJ, Lee DK, Kim JY, Kim H, Son HJ. Enhancement of Organic Photovoltaic Efficiency via Nanomorphology Control using Conjugated Polymers Incorporating Fullerene Compatible Side-Chains. Macromolecules 2015. [DOI: 10.1021/ma502546b] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Sungmin Park
- Photoelectronic
Hybrid Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea
- Department
of Chemistry, Korea University, Seoul 136-713, Korea
| | - Dongkyun Seo
- Department
of Chemistry, Chung-Ang University, Seoul 156-756, Korea
| | - Tae In Ryu
- School
of Chemical Engineering, Sungkyunkwan University, Suwon 440-746, Korea
| | - Gukil Ahn
- Department
of Physics, Sogang University, Seoul 121-742, Korea
| | - Kyungwon Kwak
- Department
of Chemistry, Chung-Ang University, Seoul 156-756, Korea
| | - Hyunjung Kim
- Department
of Physics, Sogang University, Seoul 121-742, Korea
| | | | - Nam-Gyu Park
- School
of Chemical Engineering, Sungkyunkwan University, Suwon 440-746, Korea
- Department
of Energy Science, Sungkyunkwan University, Suwon 440-746, Korea
| | - BongSoo Kim
- Photoelectronic
Hybrid Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea
| | - Min Jae Ko
- Photoelectronic
Hybrid Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea
| | - Doh-Kwon Lee
- Photoelectronic
Hybrid Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea
| | - Jin Young Kim
- Photoelectronic
Hybrid Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea
| | - Honggon Kim
- Photoelectronic
Hybrid Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea
| | - Hae Jung Son
- Photoelectronic
Hybrid Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea
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22
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Li Y, Yoo K, Lee DK, Kim JY, Son HJ, Kim JH, Lee CH, Míguez H, Ko MJ. Synergistic strategies for the preparation of highly efficient dye-sensitized solar cells on plastic substrates: combination of chemical and physical sintering. RSC Adv 2015. [DOI: 10.1039/c5ra10290a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Synergistic strategies combining chemical and physical sintering at low temperature were employed for the preparation of highly efficient dye-sensitized solar cells on plastic substrates.
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Affiliation(s)
- Yuelong Li
- Photo-Electronic Hybrids Research Center
- Korea Institute of Science and Technology
- Seoul 02792
- Republic of Korea
- Instituto de Ciencia de Materiales de Sevilla
| | - Kicheon Yoo
- Photo-Electronic Hybrids Research Center
- Korea Institute of Science and Technology
- Seoul 02792
- Republic of Korea
- Department of Chemical and Biomolecular Engineering
| | - Doh-Kwon Lee
- Photo-Electronic Hybrids Research Center
- Korea Institute of Science and Technology
- Seoul 02792
- Republic of Korea
- Green School
| | - Jin Young Kim
- Photo-Electronic Hybrids Research Center
- Korea Institute of Science and Technology
- Seoul 02792
- Republic of Korea
- Department of Materials Science and Engineering
| | - Hae Jung Son
- Photo-Electronic Hybrids Research Center
- Korea Institute of Science and Technology
- Seoul 02792
- Republic of Korea
| | - Jong Hak Kim
- Department of Chemical and Biomolecular Engineering
- Yonsei University
- Republic of Korea
| | - Chul-Ho Lee
- Department of Materials Science and Engineering
- Seoul National University
- Seoul 08826
- Republic of Korea
| | - Hernán Míguez
- Instituto de Ciencia de Materiales de Sevilla
- Consejo Superior de Investigaciones Científicas
- 41092 Sevilla
- Spain
| | - Min Jae Ko
- Photo-Electronic Hybrids Research Center
- Korea Institute of Science and Technology
- Seoul 02792
- Republic of Korea
- Green School
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23
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Jung H, Koo B, Kim JY, Kim T, Son HJ, Kim B, Kim JY, Lee DK, Kim H, Cho J, Ko MJ. Enhanced photovoltaic properties and long-term stability in plasmonic dye-sensitized solar cells via noncorrosive redox mediator. ACS Appl Mater Interfaces 2014; 6:19191-19200. [PMID: 25296336 DOI: 10.1021/am5051982] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We demonstrate the localized surface plasmon resonance (LSPR) effect, which can enhance the photovoltaic properties of dye-sensitized solar cells (DSSCs), and the long-term stability of size-controlled plasmonic structures using a noncorrosive redox mediator. Gold nanoparticles (Au NPs) were synthesized with a phase transfer method based on ligand exchange. This synthetic method is advantageous because the uniformly sized Au NPs, can be mass produced and easily applied to DSSC photoanodes. The plasmonic DSSCs showed an 11% improvement of power conversion efficiency due to the incorporation of 0.07 wt % Au NPs, compared to the reference DSSCs without Au NPs. The improved efficiency was primarily due to the enhanced photocurrent generation by LSPR effect. With the cobalt redox mediator, the long-term stability of the plasmonic structures also significantly increased. The plasmonic DSSCs with cobalt(II/III) tris(2,2'-bipyridine) ([Co(bpy)3](2+/3+)) redox mediator maintained the LSPR effect with stable photovoltaic performance for 1000 h. This is, to our knowledge, the first demonstration of the long-term stability of plasmonic nanostructures in plasmonic DSSCs based on liquid electrolytes. As a result, the enhanced long-term stability of plasmonic NPs via a noncorrosive redox mediator will increase the feasibility of plasmonic DSSCs.
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Affiliation(s)
- Heesuk Jung
- Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST) , Seoul 136-791, Korea
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24
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Park BI, Hwang Y, Lee SY, Lee JS, Park JK, Jeong J, Kim JY, Kim B, Cho SH, Lee DK. Solvent-free synthesis of Cu2ZnSnS4 nanocrystals: a facile, green, up-scalable route for low cost photovoltaic cells. Nanoscale 2014; 6:11703-11711. [PMID: 25091974 DOI: 10.1039/c4nr02564d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Efficient Cu2ZnSnSe4 (CZTSe) solar cells were fabricated with a simple, environmentally friendly, and scalable synthetic method for Cu2ZnSnS4 (CZTS) nanocrystals. CZTS nanoparticles were mechanochemically synthesized from elemental precursors on a relatively large scale (∼20 g), during which no solvents or additives were used, thus alleviating the complex process of particle synthesis. An analysis of the time evolution of the crystalline phase and morphology of precursor powders revealed that the formation of the CZTS compound was completed in 0.5 h once initiated, suggesting that the mechanochemically induced self-propagating reaction prevails. CZTS ink was prepared by dispersing the as-synthesized nanoparticles in an environmentally benign solvent (160 mg mL(-1) in ethanol) without using any additives, after which it was cast onto Mo-coated glass substrates by a doctor-blade method. Subsequent reactive annealing at 560 °C under a Se-containing atmosphere resulted in substantial grain growth along with the nearly complete substitution of Se. The CZTSe solar cells therefrom exhibited power conversion efficiency levels as high as 6.1% (based on the active area, 0.44 cm(2)) with a relatively high open-circuit voltage (0.42 V) in comparison with the bandgap energy of 1.0 eV.
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Affiliation(s)
- Bo-In Park
- Center for Materials Architecturing, Korea Institute of Science and Technology (KIST), Seoul 136-791, Korea.
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25
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Kim I, Jeong DS, Lee WS, Kim WM, Lee TS, Lee DK, Song JH, Kim JK, Lee KS. Silicon nanodisk array design for effective light trapping in ultrathin c-Si. Opt Express 2014; 22 Suppl 6:A1431-A1439. [PMID: 25607300 DOI: 10.1364/oe.22.0a1431] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The use of ultrathin c-Si (crystalline silicon) wafers thinner than 20 μm for solar cells is a very promising approach to realize dramatic reduction in cell cost. However, the ultrathin c-Si requires highly effective light trapping to compensate optical absorption reduction. Conventional texturing in micron scale is hardly applicable to the ultrathin c-Si wafers; thus, nano scale texturing is demanded. In general, nanotexturing is inevitably accompanied by surface area enlargements, which must be minimized in order to suppress surface recombination of minority carriers. In this study, we demonstrate using optical simulations that periodic c-Si nanodisk arrays of short heights less than 200 nm and optimal periods are very useful in terms of light trapping in the ultrathin c-Si wafers while low surface area enlargements are maintained. Double side texturing with the nanodisk arrays leads to over 90% of the Lambertian absorption limit while the surface area enlargement is kept below 1.5.
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27
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Ryu TI, Yoon Y, Kim JH, Hwang DH, Ko MJ, Lee DK, Kim JY, Kim H, Park NG, Kim B, Son HJ. Simultaneous Enhancement of Solar Cell Efficiency and Photostability via Chemical Tuning of Electron Donating Units in Diketopyrrolopyrrole-Based Push–Pull Type Polymers. Macromolecules 2014. [DOI: 10.1021/ma501300a] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
| | - Youngwoon Yoon
- Photoelectronic
Hybrid Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea
| | - Ji-Hoon Kim
- Department
of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 609-735, Korea
| | - Do-Hoon Hwang
- Department
of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 609-735, Korea
| | - Min Jae Ko
- Photoelectronic
Hybrid Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea
| | - Doh-Kwon Lee
- Photoelectronic
Hybrid Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea
| | - Jin Young Kim
- Photoelectronic
Hybrid Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea
| | - Honggon Kim
- Photoelectronic
Hybrid Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea
| | | | - BongSoo Kim
- Photoelectronic
Hybrid Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea
| | - Hae Jung Son
- Photoelectronic
Hybrid Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea
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28
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Kang TY, Yoo K, Lee JA, Lee W, Kim K, Lee DK, Kim H, Ko MJ. A facile and rapid process to fabricate platinum counter electrode in dye-sensitized solar cell using nanosecond pulsed laser sintering at room temperature. J Nanosci Nanotechnol 2014; 14:5309-5312. [PMID: 24758023 DOI: 10.1166/jnn.2014.8447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
To fabricate the platinum (Pt) counter electrode in dye-sensitized solar cells (DSSCs), rapid and low sintering process was carried out using nanosecond pulsed laser sintering (LS) method based on third harmonic (355 nm) of an Nd:YAG laser at room temperature. The surface morphology of LS-Pt on fluorine-doped tin oxide (FTO) electrode showed thin and compact structure, consisting of particles size of - 10-30 nm and thickness of below 30 nm. The DSSCs with the LS-Pt/FTO counter electrodes displayed the power conversion efficiency of 4.4% with short-circuit current = 9.07 mA/cm2, open-circuit voltage = 0.79 V and fill factor = 61.3.
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29
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Jung M, Yoon Y, Park JH, Cha W, Kim A, Kang J, Gautam S, Seo D, Cho JH, Kim H, Choi JY, Chae KH, Kwak K, Son HJ, Ko MJ, Kim H, Lee DK, Kim JY, Choi DH, Kim B. Nanoscopic management of molecular packing and orientation of small molecules by a combination of linear and branched alkyl side chains. ACS Nano 2014; 8:5988-6003. [PMID: 24861723 DOI: 10.1021/nn501133y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We synthesized a series of acceptor-donor-acceptor-type small molecules (SIDPP-EE, SIDPP-EO, SIDPP-OE, and SIDPP-OO) consisting of a dithienosilole (SI) electron-donating moiety and two diketopyrrolopyrrole (DPP) electron-withdrawing moieties each bearing linear n-octyl (O) and/or branched 2-ethylhexyl (E) alkyl side chains. X-ray diffraction patterns revealed that SIDPP-EE and SIDPP-EO films were highly crystalline with pronounced edge-on orientation, whereas SIDPP-OE and SIDPP-OO films were less crystalline with a radial distribution of molecular orientations. Near-edge X-ray absorption fine structure spectroscopy disclosed an edge-on orientation with a molecular backbone tilt angle of ∼22° for both SIDPP-EE and SIDPP-EO. Our analysis of the molecular packing and orientation indicated that the shorter 2-ethylhexyl groups on the SI core promote tight π-π stacking of the molecular backbone, whereas n-octyl groups on the SI core hinder close π-π stacking to some degree. Conversely, the longer linear n-octyl groups on the DPP arms facilitate close intermolecular packing via octyl-octyl interdigitation. Quantum mechanics/molecular mechanics molecular dynamics simulations determined the optimal three-dimensional positions of the flexible alkyl side chains of the SI and DPP units, which elucidates the structural cause of the molecular packing and orientation explicitly. The alkyl-chain-dependent molecular stacking significantly affected the electrical properties of the molecular films. The edge-on oriented molecules showed high hole mobilities in organic field-effect transistors, while the radially oriented molecules exhibited high photovoltaic properties in organic photovoltaic cells. These results demonstrate that appropriate positioning of alkyl side chains can modulate crystallinity and molecular orientation in SIDPP films, which ultimately have a profound impact on carrier transport and photovoltaic performance.
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Affiliation(s)
- Minwoo Jung
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST) , Seoul 136-791, Republic of Korea
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30
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Kang W, Jung M, Cha W, Jang S, Yoon Y, Kim H, Son HJ, Lee DK, Kim B, Cho JH. High crystalline dithienosilole-cored small molecule semiconductor for ambipolar transistor and nonvolatile memory. ACS Appl Mater Interfaces 2014; 6:6589-6597. [PMID: 24708562 DOI: 10.1021/am500080p] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We characterized the electrical properties of a field-effect transistor (FET) and a nonvolatile memory device based on a solution-processable low bandgap small molecule, Si1TDPP-EE-C6. The small molecule consisted of electron-rich thiophene-dithienosilole-thiophene (Si1T) units and electron-deficient diketopyrrolopyrrole (DPP) units. The as-spun Si1TDPP-EE-C6 FET device exhibited ambipolar transport properties with a hole mobility of 7.3×10(-5) cm2/(Vs) and an electron mobility of 1.6×10(-5) cm2/(Vs). Thermal annealing at 110 °C led to a significant increase in carrier mobility, with hole and electron mobilities of 3.7×10(-3) and 5.1×10(-4) cm2/(Vs), respectively. This improvement is strongly correlated with the increased film crystallinity and reduced π-π intermolecular stacking distance upon thermal annealing, revealed by grazing incidence X-ray diffraction (GIXD) and atomic force microscopy (AFM) measurements. In addition, nonvolatile memory devices based on Si1TDPP-EE-C6 were successfully fabricated by incorporating Au nanoparticles (AuNPs) as charge trapping sites at the interface between the silicon oxide (SiO2) and cross-linked poly(4-vinylphenol) (cPVP) dielectrics. The device exhibited reliable nonvolatile memory characteristics, including a wide memory window of 98 V, a high on/off-current ratio of 1×10(3), and good electrical reliability. Overall, we demonstrate that donor-acceptor-type small molecules are a potentially important class of materials for ambipolar FETs and nonvolatile memory applications.
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Affiliation(s)
- Woonggi Kang
- SKKU Advanced Institute of Nanotechnology (SAINT), School of Chemical Engineering, Sungkyunkwan University , Suwon 440-746, Republic of Korea
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31
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Jeon JO, Lee KD, Seul Oh L, Seo SW, Lee DK, Kim H, Jeong JH, Ko MJ, Kim B, Son HJ, Kim JY. Highly efficient copper-zinc-tin-selenide (CZTSe) solar cells by electrodeposition. ChemSusChem 2014; 7:1073-1077. [PMID: 24692285 DOI: 10.1002/cssc.201301347] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Indexed: 06/03/2023]
Abstract
Highly efficient copper-zinc-tin-selenide (Cu2ZnSnSe4 ; CZTSe) thin-film solar cells are prepared via the electrodepostion technique. A metallic alloy precursor (CZT) film with a Cu-poor, Zn-rich composition is directly deposited from a single aqueous bath under a constant current, and the precursor film is converted to CZTSe by annealing under a Se atmosphere at temperatures ranging from 400 °C to 600 °C. The crystallization of CZTSe starts at 400 °C and is completed at 500 °C, while crystal growth continues at higher temperatures. Owing to compromises between enhanced crystallinity and poor physical properties, CZTSe thin films annealed at 550 °C exhibit the best and most-stable device performances, reaching up to 8.0 % active efficiency; among the highest efficiencies for CZTSe thin-film solar cells prepared by electrodeposition. Further analysis of the electronic properties and a comparison with another state-of-the-art device prepared from a hydrazine-based solution, suggests that the conversion efficiency can be further improved by optimizing parameters such as film thickness, antireflection coating, MoSe2 formation, and p-n junction properties.
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Affiliation(s)
- Jong-Ok Jeon
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Seoul 136-791 (South Korea); Department of Nanomaterials Science and Engineering, University of Science and Technology, Daejeon 305-350 (South Korea)
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32
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Lee IH, Sohn M, Lim HJ, Yoon S, Oh H, Shin S, Shin JH, Oh SH, Kim J, Lee DK, Noh DY, Bae DS, Seong JK, Bae YS. Ahnak functions as a tumor suppressor via modulation of TGFβ/Smad signaling pathway. Oncogene 2014; 33:4675-84. [PMID: 24662814 PMCID: PMC4180639 DOI: 10.1038/onc.2014.69] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 12/15/2013] [Accepted: 12/24/2013] [Indexed: 02/06/2023]
Abstract
We provide detailed mechanisms of Ahnak-mediated potentiation of transforming growth factor β (TGFβ) signaling, which leads to a negative regulation of cell growth. We show that Smad3 interacts with Ahnak through MH2 domain and that Ahnak stimulates Smad3 localization into nucleus leading to potentiating TGFβ-induced transcriptional activity of R-Smad. Moreover, overexpression of Ahnak resulted in growth retardation and cell cycle arrest through downregulation of c-Myc and cyclin D1/D2. We describe results from analyses of Ahnak−/− mouse model expressing middle T antigen in a mammary gland-specific manner (MMTVTg/+Ahnak−/−), which showed significantly progressed hyperplasia of mammary glands compared with MMTVTg/+Ahnak+/+. Finally, we screened multiple human breast cancer tissues and showed that the expression of Ahnak in cancer tissues is lower than that in control tissues by 50%. Taken together, these data indicate that Ahnak mediates a negative regulation of cell growth and acts as novel tumor suppressor through potentiation of TGFβ signaling.
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Affiliation(s)
- I H Lee
- Department of Life Sciences and GT5 program, Ewha Womans University, Seoul, Korea
| | - M Sohn
- Department of Life Sciences and GT5 program, Ewha Womans University, Seoul, Korea
| | - H J Lim
- Department of Life Sciences and GT5 program, Ewha Womans University, Seoul, Korea
| | - S Yoon
- Department of Life Sciences and GT5 program, Ewha Womans University, Seoul, Korea
| | - H Oh
- Department of Life Sciences and GT5 program, Ewha Womans University, Seoul, Korea
| | - S Shin
- Department of Life Sciences and GT5 program, Ewha Womans University, Seoul, Korea
| | - J H Shin
- Laboratory of Developmental Biology and Genomics, College of Veterinary Medicine, Seoul National University, Seoul, Korea
| | - S-H Oh
- College of Pharmacy, Gachon University, Incheon, Korea
| | - J Kim
- Department of Life Sciences and GT5 program, Ewha Womans University, Seoul, Korea
| | - D K Lee
- Department of Life Sciences and GT5 program, Ewha Womans University, Seoul, Korea
| | - D Y Noh
- Department of Surgery, School of Medicine, Seoul National University, Seoul, Korea
| | - D S Bae
- Department of Obstetrics and Gynecology, Samsung Hospital, SungKyunKwan University, Seoul, Korea
| | - J K Seong
- Laboratory of Developmental Biology and Genomics, College of Veterinary Medicine, Seoul National University, Seoul, Korea
| | - Y S Bae
- Department of Life Sciences and GT5 program, Ewha Womans University, Seoul, Korea
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33
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Tsuchiya T, Itoi T, Sofuni A, Itokawa F, Lee DK. Biliary duct-to-duct anastomosis using magnets in a Billroth II gastrectomy patient. Endoscopy 2014; 45 Suppl 2 UCTN:E243-4. [PMID: 24008446 DOI: 10.1055/s-0032-1310071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Affiliation(s)
- T Tsuchiya
- Department of Gastroenterology and Hepatology, Tokyo Medical University Hospital, Shinjuku-ku, Tokyo, Japan.
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34
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Yoon Y, Kim HJ, Cho CH, Kim S, Son HJ, Ko MJ, Kim H, Lee DK, Kim JY, Lee W, Kim BJ, Kim B. Carrier lifetime extension via the incorporation of robust hole/electron blocking layers in bulk heterojunction polymer solar cells. ACS Appl Mater Interfaces 2014; 6:333-9. [PMID: 24256096 DOI: 10.1021/am404381e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We report the achievement of a power conversion efficiency (PCE) improvement in P3HT:PCBM-based bulk-heterojunction type polymer solar cells using photocrosslinked P3HT (c-P3HT) as the electron blocking/hole extraction layer and titanium oxide nanoparticles (TiO2) as the hole blocking/electron extraction layer. Devices prepared with a 20 nm thick c-P3HT layer showed an improved PCE of 3.4% compared to devices prepared without the c-P3HT layer (PCE = 3.0%). This improvement was attributed to an extension in the carrier lifetime and an enhancement in the carrier mobility. The incorporation of the c-P3HT layer lengthened (by more than a factor of 2) the carrier lifetime and increased (by a factor of 5) the hole mobility. These results suggest that the c-P3HT layer not only prevented non-geminate recombination but it also improved carrier transport. The PCE was further improved to 4.0% through the insertion of a TiO2 layer that acted as an effective hole-blocking layer at the interface between the photoactive layer and the cathode. This work demonstrates that the incorporation of solution-processable hole and electron blocking/extraction layers offers an effective means for preventing nongeminate recombination at the interfaces between a photoactive layer and an electrode in bulk-heterojunction-type polymer solar cells.
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Affiliation(s)
- Youngwoon Yoon
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology , Seoul 136-791, Republic of Korea
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Lim YS, Kwon HS, Jeong J, Kim JY, Kim H, Ko MJ, Jeong U, Lee DK. Colloidal solution-processed CuInSe2 solar cells with significantly improved efficiency up to 9% by morphological improvement. ACS Appl Mater Interfaces 2014; 6:259-267. [PMID: 24328265 DOI: 10.1021/am4040976] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We demonstrate here that an improvement in the green density leads to a great enhancement in the photovoltaic performance of CuInSe2 (CISe) solar cells fabricated with Cu-In nanoparticle precursor films via colloidal solution deposition. Cold-isostatic pressing (CIP) increases the precursor film density by ca. 20%, which results in an appreciable improvement in the microstructural features of the sintered CISe film in terms of a lower porosity, a more uniform surface morphology, and a thinner MoSe2 layer. The low-band-gap (1.0 eV) CISe solar cells with the CIP-treated films exhibit greatly enhanced open-circuit voltage (V(OC), typically from 0.265 to 0.413 V) and fill factor (FF, typically from 0.34 to 0.55), compared to the control devices. As a consequence, an almost 3-fold increase in the average efficiency, from 3.0 to 8.2% (with the highest value of 9.02%), is realized. Diode analysis reveals that the enhanced V(OC) and FF are essentially attributed to the reduced reverse saturation current density and diode ideality factor. This is associated with suppressed recombination, likely due to the reduction in recombination sites at grain/air surfaces, intergranular interfaces, and defective CISe/CdS junctions. From the temperature dependences of V(OC), it is revealed that CIP-treated devices suffer less from interface recombination.
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Affiliation(s)
- Ye Seul Lim
- Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST) , Seoul 136-791, Korea
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Park SM, Yoon Y, Jeon CW, Kim H, Ko MJ, Lee DK, Kim JY, Son HJ, Kwon SK, Kim YH, Kim B. Synthesis of phenanthro[1,10,9,8-cdefg]carbazole-based conjugated polymers for organic solar cell applications. ACTA ACUST UNITED AC 2013. [DOI: 10.1002/pola.27059] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- So Min Park
- School of Materials Science and Engineering; Engineering Research Institute, Gyeongsang National University; Jinju 660-701 Korea
| | - Youngwoon Yoon
- Photo-electronic Hybrids Research Center; Korea Institute of Science and Technology (KIST); Seoul 136-791 Republic of Korea
| | - Chan Woo Jeon
- Department of Chemistry; Gyeongsang National University; JinJu 660-701 Korea
| | - Honggon Kim
- Photo-electronic Hybrids Research Center; Korea Institute of Science and Technology (KIST); Seoul 136-791 Republic of Korea
| | - Min Jae Ko
- Photo-electronic Hybrids Research Center; Korea Institute of Science and Technology (KIST); Seoul 136-791 Republic of Korea
| | - Doh-Kwon Lee
- Photo-electronic Hybrids Research Center; Korea Institute of Science and Technology (KIST); Seoul 136-791 Republic of Korea
| | - Jin Young Kim
- Photo-electronic Hybrids Research Center; Korea Institute of Science and Technology (KIST); Seoul 136-791 Republic of Korea
| | - Hae Jung Son
- Photo-electronic Hybrids Research Center; Korea Institute of Science and Technology (KIST); Seoul 136-791 Republic of Korea
| | - Soon-Ki Kwon
- School of Materials Science and Engineering; Engineering Research Institute, Gyeongsang National University; Jinju 660-701 Korea
| | - Yun-Hi Kim
- Department of Chemistry; Gyeongsang National University; JinJu 660-701 Korea
| | - BongSoo Kim
- Photo-electronic Hybrids Research Center; Korea Institute of Science and Technology (KIST); Seoul 136-791 Republic of Korea
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Han JW, Jang SI, Ma DW, Yoon SO, Lee DK. Invaginated ampulla of Vater in synchronous malignant intraductal papillary mucinous neoplasm of the pancreas and common bile duct cancer. Endoscopy 2013; 45 Suppl 2 UCTN:E25-6. [PMID: 23468151 DOI: 10.1055/s-0032-1326106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Affiliation(s)
- J W Han
- Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
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Lim H, Jang HW, Lee DK, Kim I, Hwang CS, Jeong DS. Elastic resistance change and action potential generation of non-faradaic Pt/TiO2/Pt capacitors. Nanoscale 2013; 5:6363-6371. [PMID: 23733132 DOI: 10.1039/c3nr02154h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Electric current in the mixed ionic-electronic conductor TiO2 is hysteretic, i.e. history-dependent, and its use is versatile in electronic devices. Nowadays, biologically inspired, analogue-type computing systems, known as neuromorphic systems, are being actively investigated owing to their new and intriguing physical concepts. The realization of artificial synapses is important for constructing neuromorphic systems. In mammalians' brains, the plasticity of synapses between neighbouring nerve cells arises from action potential firing. Emulating action potential firing via inorganic systems has therefore become important in neuromorphic engineering. In this work, the current-voltage hysteresis of TiO2-based non-faradaic capacitors is investigated to primarily focus on the correlation between the blocking contact and the elasticity, i.e. non-plasticity, of the capacitors' resistance change, in experimental and theoretical methods. The similarity between the action potential firing behaviour in nerve cells and the elasticity of the non-faradaic capacitors is addressed.
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Affiliation(s)
- Hyungkwang Lim
- Electronic Materials Research Centre, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Republic of Korea
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Zhang C, Zhang P, Mo C, Yang W, Li Q, Pan L, Lee DK. Cadmium uptake, chemical forms, subcellular distribution, and accumulation in Echinodorus osiris Rataj. Environ Sci Process Impacts 2013; 15:1459-65. [PMID: 23764771 DOI: 10.1039/c3em00002h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Phytoremediation is a technology for extracting or inactivating pollutants in soil. Echinodorus osiris (E. osiris) is a fast growing perennial wetland plant that is common in tropical and subtropical areas and has a high tolerance to cadmium (Cd). However, the absorption dynamics, subcellular distribution and accumulation of Cd by E. osiris had not been investigated. In this paper, hydroponic experiments with different levels of Cd(2+) (0, 5.0, 15.0 mg L(-1)) were carried out to determine these characteristics of E. osiris. The results indicated that the Cd absorption rate of Echinodorus osiris decreased over time, and the absorption rate within 0.5-1.0 h was faster than after 1.0 h. In a 6.0 hour time period, the rate of Cd uptake fit a quadratic polynomial curve when E. osiris was grown under the 5 mg L(-1) Cd treatment. However, the rate of Cd uptake by E. osiris fit a cubic polynomial model with the 15 mg L(-1) Cd treatment. In the roots, the ethanol-extractable Cd, water-extractable Cd, and NaCl-extractable Cd were the largest proportions of the total Cd. The HAc-extractable Cd, HCl-extractable Cd, and residual-Cd represented a larger proportion of the total Cd in the leaves which was combined with phosphate including CdHPO4, Cd3 (PO4)2, and oxalic acid. When analyzing the subcellular distribution of Cd in the plant, the soluble fraction containing Cd accounted for the largest part (69.49-88.39%) followed by the Cd bound to the cell wall (8.44-25.62%). Both the lower and the higher Cd treatments demonstrated that compartmentation by the vacuole and cell wall binding were two effective defense mechanisms of the plant. However, the vacuole became the main site for Cd accumulation in the leaves under the 15 mg L(-1) Cd treatment. E. osiris was able to accumulate high concentrations of Cd in both the roots and the leaves. The Cd concentration reached 502.97 mg kg(-1) and 2742.95 mg kg(-1) in the shoots and roots, respectively, after 27 days of cultivation. It was concluded that E. osiris is a potential hyperaccumulator of Cd.
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Affiliation(s)
- Chaolan Zhang
- School of Environment, Guangxi University, Nanning, Guangxi 530004, PR China.
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Kim B, Park SW, Kim JY, Yoo K, Lee JA, Lee MW, Lee DK, Kim JY, Kim B, Kim H, Han S, Son HJ, Ko MJ. Rapid dye adsorption via surface modification of TiO2 photoanodes for dye-sensitized solar cells. ACS Appl Mater Interfaces 2013; 5:5201-5207. [PMID: 23679678 DOI: 10.1021/am401034r] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A facile method for increasing the reaction rate of dye adsorption, which is the most time-consuming step in the production of dye-sensitized solar cells (DSSCs), was developed. Treatment of a TiO2 photoanode with aqueous nitric acid solution (pH 1) remarkably reduced the reaction time required to anchor a carboxylate anion of the dye onto the TiO2 nanoparticle surface. After optimization of the reaction conditions, the dye adsorption process became 18 times faster than that of the conventional adsorption method. We studied the influence of the nitric acid treatment on the properties of TiO2 nanostructures, binding modes of the dye, and adsorption kinetics, and found that the reaction rate improved via the synergistic effects of the following: (1) electrostatic attraction between the positively charged TiO2 surface and ruthenium anion increases the collision frequency between the adsorbent and the anchoring group of the dye; (2) the weak anchoring affinity of NO3(-) in nitric acid with metal oxides enables the rapid coordination of an anionic dye with the metal oxide; and (3) sufficient acidity of the nitric acid solution effectively increases the positive charge density on the TiO2 surface without degrading or transforming the TiO2 nanostructure. These results demonstrate the developed method is effective for reducing the overall fabrication time without sacrificing the performance and long-term stability of DSSCs.
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Affiliation(s)
- Boeun Kim
- Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), Seoul 136-791, Republic of Korea
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Li Y, Yoo K, Lee DK, Kim JY, Kim H, Kim B, Ko MJ. Photovoltaic properties of high efficiency plastic dye-sensitized solar cells employing interparticle binding agent "nanoglue". Nanoscale 2013; 5:4711-4719. [PMID: 23340722 DOI: 10.1039/c2nr33352j] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
An interparticle binding agent, or nanoglue, was synthesized by a sol-gel process, which facilitated the preparation of well-interconnected TiO2 electrodes at low-temperatures for plastic dye-sensitized solar cells. The viscosity of the nanoglue-based pastes was seven times higher than that obtained in pastes without any nanoglue. The increased viscosity was sufficiently high enough for coating thick films to fabricate TiO2 electrodes. The structural and photovoltaic properties of the films were extensively investigated by varying the amounts of nanoglue. A reduced pore size and greatly enhanced surface area were observed in the nanoglue-based films. Improved interparticle connectivity, resulting in faster electron transport, was confirmed by photocurrent transient spectroscopy and electrochemical impedance measurements of the nanoglue-based films. The electron diffusion length and charge collection efficiency were also enhanced in these nanoglue-based films. A maximum conversion efficiency of 5.43% was achieved in films containing 20 wt% nanoglue fabricated on a plastic substrate under one-sun illumination, even without any additional treatment.
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Affiliation(s)
- Yuelong Li
- Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea
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Park SJ, Yoo K, Kim JY, Kim JY, Lee DK, Kim B, Kim H, Kim JH, Cho J, Ko MJ. Water-based thixotropic polymer gel electrolyte for dye-sensitized solar cells. ACS Nano 2013; 7:4050-4056. [PMID: 23618493 DOI: 10.1021/nn4001269] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
For the practical application of dye-sensitized solar cells (DSSCs), it is important to replace the conventional organic solvents based electrolyte with environmentally friendly and stable ones, due to the toxicity and leakage problems. Here we report a noble water-based thixotropic polymer gel electrolyte containing xanthan gum, which satisfies both the environmentally friendliness and stability against leakage and water intrusion. For application in DSSCs, it was possible to infiltrate the prepared electrolyte into the mesoporous TiO2 electrode at the fluidic state, resulting in sufficient penetration. As a result, this electrolyte exhibited similar conversion efficiency (4.78% at 100 mW cm(-2)) and an enhanced long-term stability compared to a water-based liquid electrolyte. The effects of water on the photovoltaic properties were examined elaborately from the cyclic voltammetry curves and impedance spectra. Despite the positive shift in the conduction band potential of the TiO2 electrode, the open-circuit voltage was enhanced by addition of water in the electrolyte due to the greater positive shift in the I(-)/I3(-) redox potential. However, due to the dye desorption and decreased diffusion coefficient caused by the water content, the short-circuit photocurrent density was reduced. These results will provide great insight into the development of efficient and stable water-based electrolytes.
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Affiliation(s)
- Se Jeong Park
- Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea
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Lee H, Lee W, Kim JY, Ko MJ, Kim K, Seo K, Lee DK, Kim H. Highly dense and crystalline CuInSe2 thin films prepared by single bath electrochemical deposition. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2012.09.118] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Jang SI, Kim JH, Kim M, Yang S, Jo EA, Lee JW, Na K, Kim JM, Jeong S, Lee DH, Lee DK. Porcine feasibility and safety study of a new paclitaxel-eluting biliary stent with a Pluronic-containing membrane. Endoscopy 2012; 44:825-31. [PMID: 22752887 DOI: 10.1055/s-0032-1309881] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND AND STUDY AIM Metal stents for malignant biliary obstruction are susceptible to occlusion by tumor ingrowth or overgrowth. Therefore, we previously reported our use of a metal stent covered with a paclitaxel-incorporated membrane giving an antitumor effect to prevent occlusion from tumor ingrowth. We have also developed a new generation of paclitaxel-eluting biliary stent using a membrane containing Pluronic F-127 for effective drug delivery. The aim of this study was to investigate the safety and efficacy of drug delivery for this newly developed stent in the biliary tract. METHODS Metal stents were coated with paclitaxel and various concentrations of Pluronic F-127 in phosphate-buffered saline solution. Stents containing varying concentrations were placed in the bile ducts of eight pigs divided as follows: group I, 0% Pluronic + 0% paclitaxel; group II, 0% Pluronic + 10% paclitaxel; group III, 10% Pluronic + 10% paclitaxel; group IV, 20% Pluronic + 10% paclitaxel. The histology of the porcine bile duct and the amount of paclitaxel in the porcine serum were examined. The amount of paclitaxel released was also measured in vitro. RESULTS Histologic changes in the porcine biliary epithelium were acceptable in terms of safety, based on inflammatory cell infiltration and fibrotic reaction. No significant differences in histology were observed between the groups. In the porcine serum analysis, released paclitaxel was detected for 28 days with the 10% Pluronic concentration (group III). However, released paclitaxel was observed for only 7 days in groups II and IV. In the in vitro experiments, long-lasting release of paclitaxel was also noted from the stent with 10% Pluronic. CONCLUSIONS The new paclitaxel-eluting stent with 10% Pluronic F-127 is safe and provides enhanced local drug delivery.
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Affiliation(s)
- S I Jang
- Department of Internal Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
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Lee W, Yoo B, Kim K, Lee DK, Kim H, Ko MJ. Suppressed recombination in quantum dot-sensitized solar cells with blocking layers on FTO substrates. J Nanosci Nanotechnol 2012; 12:1492-1496. [PMID: 22629986 DOI: 10.1166/jnn.2012.4579] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The compact and thin TiO2 blocking layers (c-TiO2) were formed on F-doped SnO2 (FTO) substrate in quantum dots-sensitized solar cells (QSSCs) by chemical deposition. The c-TiO2 layers induced indirect contact between electrolyte and FTO electrode, which reduced leakage in QSSCs. The QSSCs showed power conversion efficiency (Eff) of 3.85% in the presence of c-TiO2 layers which leads to 21% improved compared to that without c-TiO2 layers (Eff = 3.18%). The presence of the c-TiO2 layers in QSSCs also improved the stability under illumination.
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Affiliation(s)
- Wonjoo Lee
- Korea Institute of Science and Technology, 39-1 Hawolkok-Dong, Sungbuk-Ku, Seoul, 136-791, Republic of Korea
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Yoo BH, Kim KK, Lee DK, Kim HG, Kim BS, Park NG, Ko MJ. Blocking Layers Deposited on TCO Substrate and Their Effects on Photovoltaic Properties in Dye-Sensitized Solar Cells. J ELECTROCHEM SCI TE 2011. [DOI: 10.33961/jecst.2011.2.2.068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Yoo BH, Kim KK, Lee DK, Kim HG, Kim BS, Park NG, Ko MJ. Blocking Layers Deposited on TCO Substrate and Their Effects on Photovoltaic Properties in Dye-Sensitized Solar Cells. J ELECTROCHEM SCI TE 2011. [DOI: 10.5229/jecst.2011.2.2.068] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Park SW, Lee K, Lee DK, Ko MJ, Park NG, Kim K. Expanding the spectral response of a dye-sensitized solar cell by applying a selective positioning method. Nanotechnology 2011; 22:045201. [PMID: 21157013 DOI: 10.1088/0957-4484/22/4/045201] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We have developed a facile method to position different dyes (N719 and N749) sequentially in a mesoporous TiO(2) layer through selective desorption and adsorption processes. From the selective removal of the only upper part of the first adsorbed dye, double-layered dye-sensitized solar cells have been successfully achieved without any damage to the dye. From the incident photon-to-current conversion efficiency (IPCE) measurement, the multi-layered dye-sensitized solar cell (MDSSC) was found to exhibit an expanded spectral response for the solar spectrum while maintaining the maximum IPCE value of each single-layered cell. The highest photocurrent density, 19.3 mA cm( - 2), was obtained from the MDSSC utilizing an N719/N749 bi-layered mesoporous TiO(2) film. The power conversion efficiency of 9.8% was achieved from the MDSSC, which is higher than that of single N719-or N749-based cells and cocktail-dyed (a mixture of N719 and N749) cells.
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Affiliation(s)
- Se Woong Park
- Solar Cell Center, Energy Division, Korea Institute of Science and Technology (KIST), Seoul 136-791, Korea
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Lee DK, Fischer CC, Valov I, Reinacher J, Stork A, Lerch M, Janek J. An EMF cell with a nitrogen solid electrolyte--on the transference of nitrogen ions in yttria-stabilized zirconia. Phys Chem Chem Phys 2011; 13:1239-42. [PMID: 21079879 DOI: 10.1039/c003991h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The mobility and electrochemical activity of nitrogen inside and/or at the surface of ionic compounds is of fundamental, as well as of possibly practical, relevance. In order to better understand the role of nitrogen anions in solid electrolytes, we measured the transference number of nitrogen in yttria-stabilized zirconia (YSZ) by a concentration cell technique as a function of oxygen activity at different temperatures in the range of 1023 ≤T/K≤ 1123. YSZ doped with 1.9 wt% of N (YSZ:N) turned out to have an appreciable nitrogen transference number, which increased from 0 to 0.1 with decreasing oxygen activity in the range of -20 < log a(O(2)) < -14. The stability of N in YSZ:N, however, has yet to be elucidated under oxidizing conditions.
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Affiliation(s)
- Doh-Kwon Lee
- Institute of Physical Chemistry, Justus-Liebig-University, Heinrich-Buff-Ring 58, D-35392 Giessen, Germany
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