30 results on '"Sora Oh"'
Search Results
2. Rational design of the S, <scp>N‐heteroacene‐based nonfullerene</scp> by introducing the fluorine atom for efficient <scp>high‐performance</scp> organic solar cells
- Author
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Sora Oh, Mufarah Amjad, Taek Ahn, and Sang Kyu Lee
- Subjects
General Chemistry - Published
- 2023
3. Photovoltaic Effect of Structure Compatibility Utilizing a Same Electron-Accepting Unit on a Polymer Donor and Nonfused Nonfullerene Acceptor
- Author
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Huyen Tran, Sora Oh, Ji-Young Jeong, Namsun Yoon, Chang Eun Song, Hang Ken Lee, Won Suk Shin, Jong-Cheol Lee, and Sang Kyu Lee
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Materials Chemistry ,Electrochemistry ,Energy Engineering and Power Technology ,Chemical Engineering (miscellaneous) ,Electrical and Electronic Engineering - Published
- 2022
4. Alkoxy substituted wide bandgap conjugated polymer for non-fullerene polymer solar cells
- Author
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Taek Ahn, Sang Kyu Lee, and Sora Oh
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chemistry.chemical_classification ,Materials science ,Fullerene ,Organic solar cell ,General Chemistry ,Polymer ,Conjugated system ,Condensed Matter Physics ,Photochemistry ,Acceptor ,Polymer solar cell ,chemistry.chemical_compound ,chemistry ,Alkoxy group ,Thiophene ,General Materials Science - Abstract
A new wide bandgap (WBG) conjugated polymer diO-PBDB-T containing alkoxy substituted thiophene spacer was designed and synthesized for application as a donor in nonfullerene acceptor (NFA) based po...
- Published
- 2021
5. Effects of Electron-Donating and Electron-Accepting Substitution on Photovoltaic Performance in Benzothiadiazole-Based A–D–A′–D–A-Type Small-Molecule Acceptor Solar Cells
- Author
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Won Suk Shin, Hang Ken Lee, Namsun Yoon, Sang-Jin Moon, Ji-Young Jeong, Chang Eun Song, Jong-Cheol Lee, Sang Kyu Lee, and Sora Oh
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Materials science ,Absorption spectroscopy ,Organic solar cell ,Substitution (logic) ,Photovoltaic system ,Energy Engineering and Power Technology ,Electron ,Photochemistry ,Small molecule ,Acceptor ,Materials Chemistry ,Electrochemistry ,Chemical Engineering (miscellaneous) ,Electrical and Electronic Engineering - Abstract
A–D–A′–D–A-type nonfused-ring acceptors (NFRAs) have recently received extensive attention because of their suitable tuning of absorption spectra, frontier energy levels, and promising sunlight har...
- Published
- 2020
6. Non-halogenated solvent-processed ternary-blend solar cells via alkyl-side-chain engineering of a non-fullerene acceptor and their application in large-area devices
- Author
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Chang Eun Song, Dongwook Kim, Eunhee Lim, Sang Kyu Lee, Won Suk Shin, Shafket Rasool, Taeho Lee, and Sora Oh
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chemistry.chemical_classification ,Materials science ,Organic solar cell ,Renewable Energy, Sustainability and the Environment ,02 engineering and technology ,General Chemistry ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Acceptor ,0104 chemical sciences ,law.invention ,Solvent ,chemistry ,Coating ,Chemical engineering ,law ,Side chain ,engineering ,General Materials Science ,Crystallization ,Solubility ,0210 nano-technology ,Alkyl - Abstract
Solution processability is one of the advantages of organic solar cells (OSCs). However, most high-efficiency OSCs are prepared using hazardous chlorinated solvents for the deposition of photoactive layers. The replacement of non-halogenated solvents with eco-friendly green solvents for photoactive materials is urgently required. Herein, we have developed a novel asymmetric T2-OEHRH, which is modified from the symmetric T2-ORH. The introduction of asymmetric alkyl side chains onto rhodanine end groups can effectively suppress excessive self-aggregation/crystallization and substantially improve solubility without sacrificing optoelectrical properties. Therefore, ternary-blend OSCs based on PTB7-Th:EH-IDTBR:T2-OEHRH processed using a non-halogenated solvent system exhibit a uniform and favorable morphology and give a high power conversion efficiency (PCE) of 12.10%. More importantly, we demonstrate an impressive PCE of 9.32% for large-area NFA-OSCs (substrate size = 100 cm2 and aperture size = 55.5 cm2) prepared via D-bar coating in air. To our knowledge, this PCE is the highest reported to date for NFA-based large-area OSC modules processed from a non-halogenated solvent. This asymmetric alkyl-chain engineering strategy can be exploited to develop high-performance large-area NFA-OSCs with eco-friendly solvent processing.
- Published
- 2020
7. Enhanced efficiency and stability of PTB7-Th-based multi-non-fullerene solar cells enabled by the working mechanism of the coexisting alloy-like structure and energy transfer model
- Author
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Won Suk Shin, Sang Kyu Lee, Hang Ken Lee, Eunhee Lim, Chang Eun Song, Sora Oh, Ara Cho, Sang-Jin Moon, Taeho Lee, and Jong-Cheol Lee
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Materials science ,Ternary numeral system ,Organic solar cell ,Renewable Energy, Sustainability and the Environment ,Band gap ,business.industry ,Open-circuit voltage ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Acceptor ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business ,Absorption (electromagnetic radiation) ,Ternary operation ,Short circuit - Abstract
A simple-structured nonfullerene acceptor (NFA), T2-ORH, consisting of a bithiophene core and octyl-substituted rhodanine ends is utilized as the third component in ternary-blend solar cells with PTB7-Th and EH-IDTBr as host materials. T2-ORH is a wide band gap NFA and specially contributes to light absorption, which provides complimentary absorption with a low band gap acceptor, EH-IDTBR. In the ternary device, a PCE of 11.55%, a short circuit current (JSC) of 17.51 mA cm−2, a fill factor (FF) of 63% and an open circuit voltage (VOC) of 1.05 V were achieved with a 1 : 1 : 1 blend ratio. In this ternary system, it is estimated that the two NFAs work as one alloy-like acceptor and energy transfer model from T2-ORH to EH-IDTBR for efficient ternary-blend organic solar cells (OSCs). On conducting thermal, light, and air-process stability tests, the ternary-blend systems show superior stability performance owing to the formation of a stable and robust morphology. Finally, we fabricated a large-scale device (5 cm × 5 cm substrate, 13.5 cm2 aperture size, and a geometric FF of 54%) with the same ternary system. The sub-module ternary-blend OSCs displayed the highest PCE of 10.08% with JSC = 2.83 mA cm−2, VOC = 6.36 V and FF = 56%. As a result, ternary-blend OSCs show tremendous promise for use in actual applications.
- Published
- 2019
8. Synthesis and Characterization of Benzodithiophene-4,8-Dione-Based Copolymers for Polymer Solar Cells
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Sora Oh, Taek Ahn, Da Hun Kim, and Sang Kyu Lee
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chemistry.chemical_classification ,Materials science ,Open-circuit voltage ,Band gap ,Energy conversion efficiency ,Biomedical Engineering ,Bioengineering ,02 engineering and technology ,General Chemistry ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Acceptor ,Polymer solar cell ,0104 chemical sciences ,chemistry ,Copolymer ,Physical chemistry ,General Materials Science ,0210 nano-technology ,Short circuit - Abstract
A novel series of benzodithiophene-4,8-dione (BDD)-based copolymers, poly[(4,4,9,9-tetrakis(4-hexylphenyl)-4,9-dihydro-s-indacenodithiophene-2,7-diyl)-alt-(1,3-bis(2-ethylhexyl)-5,7-di(thiophene2-yl)benzodithiophene-4,8-dione)] (P1) and poly[(5,5,11,11-tetrakis(4-hexylphenyl)dithieno[2,3-d: 2',3'-d']-s-indacenodithiophene-3,9-diyl)-alt-(1,3-bis(2-ethylhexyl)-5,7-di(thiophene-2-yl)benzodithiophene-4,8-dione)] (P2), which have the same acceptor moiety but different donor segments, have been designed and synthesized for use as donor materials in solution-processable polymer solar cells (PSCs). The optical and photovoltaic properties of the copolymers were investigated. The band gaps of the copolymers were in the range 1.91-1.92 eV. Under optimized conditions, the BDD-based polymers showed power conversion efficiencies (PCEs) for the PSCs in the range 2.52-2.92% under AM 1.5 illumination (100 mW/cm2). Among the copolymers, P1, which contained an indacenodithiophene donor unit, showed a power conversion efficiency of 2.92% with a short circuit current of 7.30 mA/cm2, open circuit voltage of 0.92 V, and a fill factor of 0.43, under AM 1.5 illumination (100 mW/cm2).
- Published
- 2018
9. Synthesis and Characterization of Benzo[1,2-b:4,5-b′]Dithiophene-Based Copolymer for Organic Photovoltaic Cells
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Sachin Badgujar, Sang Kyu Lee, Taek Ahn, and Sora Oh
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Materials science ,Chemical engineering ,Photovoltaic system ,Biomedical Engineering ,Copolymer ,Organic chemistry ,General Materials Science ,Bioengineering ,General Chemistry ,Condensed Matter Physics ,Characterization (materials science) - Published
- 2017
10. A comparison of palonosetron and dexamethasone for postoperative nausea and vomiting in orthopedic patients receiving patient-controlled epidural analgesia
- Author
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Hyunzu Kim, Byung-Gun Kim, Byung-Wook Lee, Chun Woo Yang, Hyun-Kyoung Lim, and Sora Oh
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medicine.medical_specialty ,Nausea ,Epidural analgesia ,medicine.medical_treatment ,Dexamethasone ,lcsh:RD78.3-87.3 ,Patient-controlled analgesia ,03 medical and health sciences ,0302 clinical medicine ,030202 anesthesiology ,Anesthesiology ,medicine ,030212 general & internal medicine ,Adverse effect ,Postoperative nausea and vomiting ,Clinical Research Article ,business.industry ,Palonosetron ,Arthroplasty ,Anesthesiology and Pain Medicine ,lcsh:Anesthesiology ,Anesthesia ,medicine.symptom ,business ,medicine.drug - Abstract
BACKGROUND Postoperative nausea and vomiting (PONV) is one of the major concerns after anesthesia and surgery, and it may be more frequent in orthopedic patients receiving patient-controlled epidural analgesia (PCEA). The purpose of this study was to compare the effect of palonosetron and dexamethasone on the prevention of PONV in patients undergoing total joint arthroplasty and receiving PCEA. METHODS Patients scheduled for total hip or knee arthroplasty under spinal anesthesia/PCEA were randomly allocated to receive either intravenous palonosetron (0.075 mg, n = 50) or dexamethasone (5 mg, n = 50). Treatments were administered intravenously to the patients 30 min before the beginning of surgery. The total incidence of PONV and incidence in each time period, severity of nausea, need for rescue anti-emetics, pain score, and adverse effects during the first 48 h postoperatively were evaluated. RESULTS The total incidence of PONV was lower in the palonosetron group compared with the dexamethasone group (18.4% vs. 36.7%, P = 0.042), but there were no statistically significant differences in incidence between the groups at all time points. No significant intergroup differences were observed in the severity of nausea, use of rescue anti-emetics, pain score, and adverse effects. CONCLUSIONS Although there were no significant differences in the incidence of PONV between the treatment groups at all time points, intravenous palonosetron reduced the total incidence of PONV in orthopedic patients receiving PCEA compared with dexamethasone.
- Published
- 2017
11. Effects of morphology evolution on solution-processed small molecule photovoltaics via a solvent additive
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Won Suk Shin, Jong-Cheol Lee, Da Hun Kim, Shafket Rasool, Hang Ken Lee, Doan Van Vu, Sang Kyu Lee, Sora Oh, Quoc Viet Hoang, Sang-Jin Moon, and Chang Eun Song
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Materials science ,Fullerene ,Organic solar cell ,Stacking ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Acceptor ,Small molecule ,Polymer solar cell ,0104 chemical sciences ,Solvent ,Chemical engineering ,Phase (matter) ,Materials Chemistry ,Organic chemistry ,0210 nano-technology - Abstract
A newly synthesized small molecule donor, BDTT-2DPPBFu, is designed for incorporation into the photo-active layer in solution-processed small molecule organic photovoltaics (SM-OPVs). The effects of a solvent additive (1-chloronaphthalene, CN) on the bulk heterojunction morphology of a BDTT-2DPPBFu donor:fullerene derivative acceptor (PC71BM) are investigated and correlated with the device performance. A TEM analysis revealed that the nanomorphology of the SM-OPVs evolved dramatically with increasing solvent additive volume. With an optimum concentration of 2.5 vol% CN, a nanomorphology with a fibrillar and interpenetrating network on the order of exciton diffusion length (∼10–15 nm) is formed, resulting in improvement of the short-circuit current density, fill factor, and power conversion efficiency. Further GIWAXS studies have shown that the π–π stacking distance of BDTT-2DPPBFu small molecules is reduced and the inter-mixing of PC71BM within the BDTT-2DPPBFu-rich phase in the photo-active layer processed from 2.5 vol% CN is increased, leading to enhanced charge transport and reduced charge recombination and transfer resistance. The present work provides important progress in the nanomorphology of the photo-active layer, which can be effectively tuned via the use of a solvent additive in SM-OPVs.
- Published
- 2017
12. A thermally and mechanically stable solar cell made of a small-molecule donor and a polymer acceptor
- Author
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Sora Oh, Chang Eun Song, Da Hun Kim, Wang-Eun Lee, Muhammad Jahandar, Sang-Jin Moon, Sachin Badgujar, Won Suk Shin, Nasir Khan, Sang Kyu Lee, Hang Ken Lee, Shafket Rasool, and Jong-Cheol Lee
- Subjects
chemistry.chemical_classification ,Materials science ,Organic solar cell ,Renewable Energy, Sustainability and the Environment ,Photovoltaic system ,02 engineering and technology ,General Chemistry ,Polymer ,Hybrid solar cell ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,Acceptor ,Polymer solar cell ,0104 chemical sciences ,law.invention ,chemistry ,law ,Solar cell ,General Materials Science ,Thermal stability ,0210 nano-technology - Abstract
We performed systematic experiments based on a small molecule donor and a polymer acceptor containing a naphthalene diimide (NDI)-based polymer as compared with fullerene-based acceptor (PC71BM) solar cells. Among polymer acceptors, the NDI-based polymer (PNDI-2T) shows good properties such as broad light absorbance with a strong absorption co-efficient and a well oriented crystalline structure leading to high electron mobility. We monitored the photovoltaic properties of both PNDI-2T and PC71BM acceptors with a BDT2TR donor. Although the BDT2TR:PC71BM device showed a higher PCE of 8.20%, the BDT2TR:PNDI-2T device also showed remarkable photovoltaic results with a PCE of 4.43%, VOC of 0.86 V, JSC of 7.26 mA cm−2, and FF of 71% indicating one of the highest efficiencies for small molecule donor and non-fullerene polymer acceptor systems. In particular, the PNDI-2T acceptor showed excellent thermal stability and intrinsic mechanical performance as compared with the PC71BM acceptor. To demonstrate the potential of the polymer acceptor for solar devices, we fabricated a device for testing thermal stability, high thickness tolerance, and the flexibility of the solar cell with bending stress. As a result, the PNDI-2T-based solar cell exhibited excellent thermal stability at 150 °C for 15 h and the PCE of the BDT2TR:PNDI-2T device with a thick active layer (around 610 nm) maintained 80% of its initial value. Moreover, the flexible device with the BDT2TR:PNDI-2T system retained its homogeneous morphology and showed maintained photovoltaic performance even after 100 bending cycles. Therefore, PNDI-2T based organic solar cells have good potential for application as flexible and portable real energy generators.
- Published
- 2017
13. Simple and Versatile Non-Fullerene Acceptor Based on Benzothiadiazole and Rhodanine for Organic Solar Cells
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Chang Eun Song, Won-Wook So, Sora Oh, Jong-Cheol Lee, Sang-Jin Moon, Jongho Ahn, HyunKyung Lee, Hang Ken Lee, Eunhee Lim, Won Suk Shin, Sang Kyu Lee, and Sangjun Lee
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chemistry.chemical_classification ,Materials science ,Fullerene ,Organic solar cell ,Band gap ,02 engineering and technology ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,Acceptor ,0104 chemical sciences ,Organic semiconductor ,chemistry.chemical_compound ,End-group ,Rhodanine ,chemistry ,General Materials Science ,0210 nano-technology - Abstract
Most non-fullerene acceptors (NFAs) are designed in a complex planar molecular conformation containing fused aromatic rings in high-efficiency organic solar cells (OSCs). To obtain the final molecules, however, numerous synthetic steps are necessary. In this work, a novel simple-structured NFA containing alkoxy-substituted benzothiadiazole and a rhodanine end group (BTDT2R) is designed and synthesized. We also investigate the photovoltaic properties of BTDT2R-based OSCs employing representative polymer donors (wide band gap and high-crystalline P3HT, medium band gap and semicrystalline PPDT2FBT, and narrow band gap and low-crystalline PTB7-Th) to compare the performance capabilities of fullerene acceptor-based OSCs, which are well matched with various polymer donors. OSCs based on P3HT:BTDT2R, PPDT2FBT:BTDT2R, and PTB7-Th:BTDT2R achieved efficiency as high as 5.09, 6.90, and 8.19%, respectively. Importantly, photoactive films incorporating different forms of optical and molecular ordering characteristics exhibit favorable morphologies by means of solvent vapor annealing. This work suggests that the new n-type organic semiconductor developed here is highly promising as a universal NFA that can be paired with various polymer donors with different optical and crystalline properties.
- Published
- 2019
14. Stable P3HT: amorphous non-fullerene solar cells with a high open-circuit voltage of 1 V and efficiency of 4
- Author
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Sang Kyu Lee, Hang Ken Lee, HyunKyung Lee, Chang Eun Song, Won-Wook So, Won Suk Shin, Sora Oh, Sang-Jin Moon, and Jong-Cheol Lee
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Materials science ,Fullerene ,Organic solar cell ,Open-circuit voltage ,General Chemical Engineering ,Energy conversion efficiency ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Acceptor ,Polymer solar cell ,0104 chemical sciences ,Amorphous solid ,Photoactive layer ,Chemical engineering ,0210 nano-technology - Abstract
A non-fullerene small molecule acceptor, SF-HR composed of 3D-shaped spirobifluorene and hexyl rhodanine, was synthesized for use in bulk heterojunction organic solar cells (OSCs). It possesses harmonious molecular aggregation between the donor and acceptor, due to the interesting diagonal molecular shape of SF-HR. Furthermore, the energy level of SF-HR matches well with that of the donor polymer, poly(3-hexyl thiophene) (P3HT) in this system which can affect efficient charge transfer and transport properties. As a result, OSCs made from a P3HT:SF-HR photoactive layer exhibited a power conversion efficiency rate of 4.01% with a high VOC of 1.00 V, a JSC value of 8.23 mA cm−2, and a FF value of 49%. Moreover, the P3HT:SF-HR film showed superior thermal and photo-stability to P3HT:PC71BM. These results indicate that SF-HR is specialized as a non-fullerene acceptor for use in high-performance OSCs.
- Published
- 2019
15. Highly efficient and thermally stable fullerene-free organic solar cells based on a small molecule donor and acceptor
- Author
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Sang Jin Moon, Sora Oh, Sang Kyu Lee, Sachin Badgujar, In Hwan Jung, Chang Eun Song, Jong Cheol Lee, and Won Suk Shin
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Materials science ,Fullerene ,Organic solar cell ,Renewable Energy, Sustainability and the Environment ,business.industry ,Energy conversion efficiency ,02 engineering and technology ,General Chemistry ,Hybrid solar cell ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Acceptor ,Small molecule ,Polymer solar cell ,0104 chemical sciences ,Chemical engineering ,Optoelectronics ,General Materials Science ,Thermal stability ,0210 nano-technology ,business - Abstract
We studied fullerene-free organic solar cells based on electron-donating (BDT3TR) and -accepting (O-IDTBR) small molecules. Bulk heterojunction devices comprising BDT3TR:O-IDTBR showed an excellent power conversion efficiency exceeding 7% and much better thermal stability than BDT3TR:PC70BM devices after ageing at 120 °C for 300 hours.
- Published
- 2016
16. Alkyl side-chain dependent self-organization of small molecule and its application in high-performance organic and perovskite solar cells
- Author
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Chang Eun Song, Huyen Tran, Seon-Mi Jin, Eunji Lee, Sora Oh, Hang Ken Lee, Won Suk Shin, Sang-Jin Moon, Jong-Cheol Lee, Sang Kyu Lee, Namsun Yoon, and Nasir Khan
- Subjects
chemistry.chemical_classification ,Materials science ,Fullerene ,Organic solar cell ,Renewable Energy, Sustainability and the Environment ,business.industry ,Doping ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Small molecule ,Effective nuclear charge ,0104 chemical sciences ,Organic semiconductor ,chemistry ,Optoelectronics ,General Materials Science ,Electrical and Electronic Engineering ,0210 nano-technology ,business ,Alkyl ,Perovskite (structure) - Abstract
The molecular self-organization of organic semiconductors, which is mainly determined by the structural design, film processing, and device configuration, is one of the crucial factors for achieving high-performance organic photovoltaics (OPVs) and perovskite solar cells (PvSCs). In this study, we newly synthesized and developed strongly self-organized small molecules via alkyl side-chain engineering. Replacing “H” to “C6H13” on the thienyl group, SM2 showed a well-ordered face-on orientation. Due to favorable self-organization leading to effective charge carrier dynamics, including enhanced charge transfer/transport and suppressed recombination, SM2-based OPVs and PvSCs exhibited improved device performance compared to the devices based on SM1 without an additional hexyl side-chain. The best fullerene-based OPV and planar PvSC with SM2 as a small-molecule donor and as a hole transport layer (HTL) achieved an unprecedentedly high efficiency of 9.38% and 20.56%, in contrast with SM1-based devices showing lower efficiency of 8.70% and 15.37%. Furthermore, the planar PvSCs based on undoped-SM2 HTL exhibited comparable efficiency but provided excellent heat and humidity stability compared with doped spiro-OMeTAD-based devices. These results clearly indicated that SM2 with highly-ordered and favorable self-organization is a promising organic semiconductor for future applications of high-performance organic and inorganic-organic hybrid electronics.
- Published
- 2020
17. Synthesis and characterization of benzo[1,2-b:4,5-b’]dithiophene-based copolymers for polymer solar cells
- Author
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Jong-Cheol Lee, Won Suk Shin, Taek Ahn, Sora Oh, and Sang Kyu Lee
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chemistry.chemical_classification ,Materials science ,Pyrazine ,Band gap ,General Physics and Astronomy ,Polymer ,Electrochemistry ,Acceptor ,Polymer solar cell ,chemistry.chemical_compound ,Quinoxaline ,chemistry ,Polymer chemistry ,Copolymer - Abstract
Two benzo[1,2-b:4,5-b’]dithiophene (BDT)-based copolymers, poly[4,8-bis(5-(2-ethylhexyl) thiophene-2-yl)benzo[1,2-b:4,5-b’]dithiophene-alt-5,8-(2,3-bis(4-octyloxy)phenyl)quinoxaline] (P1) and poly[4,8-bis(5-(2-ethylhexyl)thiophene-2-yl)benzo[1,2-b:4,5-b’]dithiophene-alt-5,7-(2,3-bis(4- octyloxy)phenyl)thieno[3,4-b]pyrazine] (P2), are synthesized and used as donor materials in polymer solar cells (PSCs). To obtain a low band gap polymer, we use a copolymerized donor-acceptor structure. The optical, electrochemical, and photovoltaic properties of the copolymers are investigated. The results indicate that the acceptor units in the copolymers influenced the band gap, electronic energy levels, and photovoltaic properties of the copolymers significantly. The band gaps of the copolymers are in the range 1.34 − 1.75 eV. Under optimized conditions, the BDT-based polymers showed power conversion efficiencies (PCEs) for the PSCs in the range 1.46 − 2.05% under AM 1.5 illumination (100 mW/cm2).
- Published
- 2015
18. Effects on Photovoltaic Performance of Dialkyloxy-benzothiadiazole Copolymers by Varying the Thienoacene Donor
- Author
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Muhammad Jahandar, Chang Eun Song, Won-Wook So, Won Suk Shin, Shafket Rasool, Gururaj P. Kini, Jong-Cheol Lee, Sang Kyu Lee, Zaheer Abbas, and Sora Oh
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chemistry.chemical_classification ,Materials science ,Photovoltaic system ,Energy conversion efficiency ,02 engineering and technology ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,Acceptor ,Polymer solar cell ,0104 chemical sciences ,chemistry.chemical_compound ,Crystallinity ,chemistry ,Polymer chemistry ,Thiophene ,Copolymer ,General Materials Science ,0210 nano-technology - Abstract
A series of four donor-acceptor alternating copolymers based on dialkyloxy-benzothiadiazole (ROBT) as an acceptor and thienoacenes as donor units were synthesized and tested for polymer solar cells (PSCs). These new polymers had different donor units with varied electron-donating ability (thieno[3,2-b]thiophene (TT), dithieno[3,2-b:2',3'-d]thiophene (DTT), benzo[1,2-b:4,5-b']dithiophene (BDT), and naphtha[1,2-b:5,6-b']dithiophene (NDT)) in the polymer backbone. To understand the effect of these thienoacenes on the optoelectronic and photovoltaic properties of the copolymers, we systematically analyzed and compared the energy levels, crystallinity, morphology, charge recombination, and charge carrier mobility in the resulting polymers. In this series, optimized photovoltaic cells yielded power conversion efficiency (PCE) values of 6.25% (TT), 9.02% (DTT), 6.34% (BDT), and 2.29% (NDT) with different thienoacene donors. The introduction of DTT into the thienoacene-ROBT polymer enabled the generation of well-ordered molecular packings with a π-π stacking distance of 3.72 Å, high charge mobilities, and an interconnected nanofibrillar morphology in blend films. As a result, the PSC employing the polymer with DTT exhibited the highest PCE of 9.02%. Thus, our structure-property relationship studies of thienoacene-ROBT-based polymers emphasize that the molecular design of the polymers must be carefully optimized to develop high efficient PSCs. These findings will help us to understand the impact of the donor thienoacene on the optoelectronic and photovoltaic performance of polymers.
- Published
- 2017
19. Transsacrococcygeal approach to ganglion impar block for treatment of chronic coccygodynia after spinal arachnoid cyst removal
- Author
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Sora Oh, Young Deog Cha, Chun Woo Yang, Jung Uk Han, Jang Ho Song, WonJu Na, and Byung-Gun Kim
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Adult ,medicine.medical_specialty ,Coccyx ,Physical examination ,ganglion impar block ,03 medical and health sciences ,0302 clinical medicine ,030202 anesthesiology ,medicine ,case report ,Humans ,Pain Management ,Clinical Case Report ,Neurolysis ,Spinal arachnoid cyst ,Pain, Postoperative ,Ganglia, Sympathetic ,medicine.diagnostic_test ,business.industry ,Sacrococcygeal Region ,coccygodynia ,transsacrococcygeal junction ,Magnetic resonance imaging ,Nerve Block ,General Medicine ,Magnetic Resonance Imaging ,Surgery ,Blockade ,Ganglion impar ,Coccydynia ,neurolysis ,Arachnoid Cysts ,medicine.anatomical_structure ,Female ,medicine.symptom ,Chronic Pain ,business ,030217 neurology & neurosurgery ,Research Article - Abstract
Background: Coccygodynia is a pain in the region of the coccyx that radiates to the sacral, perineal area. The cause of the pain is often unknown. Coccygodynia is diagnosed through the patient's past history, a physical examination, and dynamic radiographic study, but the injection of local anesthetics or a diagnostic nerve blockade are needed to distinguish between somatic, neuropathic, and combined pain. Ganglion impar is a single retroperitoneal structure made of both paravertebral sympathetic ganglions. Although there are no standard guidelines for the treatment of coccygodynia, ganglion impar blockade is one of the effective options for treatment. Methods: Here, we report a 42-year-old female patient presenting with severe pain in the coccygeal area after spinal arachnoid cyst removal. Results: Treatment involved neurolysis with absolute alcohol on the ganglion impar through the transsacrococcygeal junction. Pain was relieved without any complications. Conclusion: Our case report offers the ganglion impar blockade using the transsacrococcygeal approach with absolute alcohol can improve intractable coccydynia.
- Published
- 2016
20. Organic Solar Cells: High-Performance Small Molecule via Tailoring Intermolecular Interactions and its Application in Large-Area Organic Photovoltaic Modules (Adv. Energy Mater. 12/2016)
- Author
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Won Suk Shin, Chang Eun Song, Sang-Jin Moon, Gang-Young Lee, Taiho Park, Sang Kyu Lee, Sachin Badgujar, Sangheon Park, Jong-Cheol Lee, and Sora Oh
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Materials science ,Organic solar cell ,Renewable Energy, Sustainability and the Environment ,business.industry ,Photovoltaic system ,Intermolecular force ,Nanotechnology ,Hybrid solar cell ,Interconnectivity ,Small molecule ,Polymer solar cell ,Intermolecular interaction ,Optoelectronics ,General Materials Science ,business - Published
- 2016
21. Saturated fatty acids enhance osteoclast survival
- Author
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Hye-Seon Choi, Ok-Joo Sul, Youn-Young Kim, Jae-Hee Suh, Hye-Jin Kim, Rina Yu, and Sora Oh
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Male ,medicine.medical_specialty ,Bone density ,MIP-1α ,Cell Survival ,Osteoclasts ,Blood lipids ,QD415-436 ,Biology ,Biochemistry ,Gene Knockout Techniques ,Mice ,Endocrinology ,Bone Marrow ,Osteoclast ,Internal medicine ,Hyperlipidemia ,medicine ,Animals ,Obesity ,Chemokine CCL3 ,osteoclast survival ,saturated fatty acid ,Fatty Acids ,food and beverages ,Cell Biology ,medicine.disease ,Toll-Like Receptor 4 ,medicine.anatomical_structure ,Apoptosis ,Myeloid Differentiation Factor 88 ,Saturated fatty acid ,TLR4 ,Bone marrow ,Research Article ,Signal Transduction - Abstract
Hyperlipidemia and marrow fat are associated with lowering bone density in vivo, suggesting that lipid contributes to bone loss. Using bone marrow-derived macrophages, we investigated the effect of saturated fatty acids (SFA) on osteoclastogenesis. The level of free fatty acids and adiposity in bone marrow was significantly elevated in obese mice. SFA increased osteoclast (OC) survival by preventing apoptosis. SFA caused the production of MIP-1alpha and led to activation of nuclear factor (NF)-kappaB in the OC. The absence of Toll-like receptor 4 (TLR4) or myeloid differentiation factor 88 (MyD88) abolished the survival effect of SFA on OC.
- Published
- 2010
22. Increased fat due to estrogen deficiency induces bone loss by elevating monocyte chemoattractant protein-1 (MCP-1) production
- Author
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Hyeyoung Lee, Hye-Seon Choi, Ok-Joo Sul, Youn-Young Kim, Hyun-Ju Kim, Song-Hee Kim, Shin-Yoon Kim, and Sora Oh
- Subjects
medicine.medical_specialty ,medicine.drug_class ,Ovariectomy ,Subcutaneous Fat ,Osteoclasts ,Intra-Abdominal Fat ,Weight Gain ,Bone resorption ,Mice ,Bone Density ,Osteoclast ,Internal medicine ,medicine ,Animals ,Femur ,Bone Resorption ,Molecular Biology ,Cells, Cultured ,Chemokine CCL2 ,Chemistry ,Macrophage Colony-Stimulating Factor ,Macrophages ,Monocyte ,RANK Ligand ,Cell Differentiation ,Estrogens ,Chemotaxis ,Cell Biology ,General Medicine ,Recombinant Proteins ,Mice, Inbred C57BL ,MCP-1 production ,Bone Diseases, Metabolic ,medicine.anatomical_structure ,Endocrinology ,Adipose Tissue ,Estrogen ,Female ,Bone marrow ,hormones, hormone substitutes, and hormone antagonists ,Monocyte chemoattractant protein - Abstract
Ovariectomy (OVX)-induced estrogen withdrawal resulted in both bone loss and an increase in fat. We observed elevated osteoclast (OC) formation by bone marrow-derived macrophages treated with medium conditioned by fats from OVX mice, but not from sham-operated mice. Fats from OVX mice expressed and secreted higher levels of monocyte chemoattractant protein-1 (MCP-1) than those from sham-operated mice. Increased fat resulting from estrogen deficiency is thus responsible for bone loss due to enhanced OC formation, which is, at least partly, a consequence of elevated MCP-1 production.
- Published
- 2010
23. Chemical structure of the interface in ultrathin HfO2/Si films
- Author
-
Moonju Cho, Ranju Jung, Cheol Seong Hwang, Sora Oh, and Jong-Cheol Lee
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,Silicon ,Binding energy ,Analytical chemistry ,chemistry.chemical_element ,Heterojunction ,Dielectric ,Electron spectroscopy ,Chemical state ,chemistry ,X-ray photoelectron spectroscopy ,Transmission electron microscopy ,Chemical physics - Abstract
The chemical states of the HfO2/Si (100) interface were investigated using transmission electron microscopy and high-resolution x-ray photoelectron spectroscopy. The depth distributions of Hf chemical states showed that the Hf 4f binding energy remains unchanged with the depth and there is no signature of more than one Hf-O state. These facts strongly suggest that the chemical state of the interfacial layer is not Hf-silicate, as previously believed. Instead, the compositions are mainly Si2O3 and SiO2, judging from the deconvolution of Si 2p spectra. The dielectric constant κ=4.8 of the interfacial layer is also consistent with the above conclusions.
- Published
- 2004
24. High-Performance Small Molecule via Tailoring Intermolecular Interactions and its Application in Large-Area Organic Photovoltaic Modules
- Author
-
Gang-Young Lee, Sachin Badgujar, Jong-Cheol Lee, Won Suk Shin, Sangheon Park, Sang Kyu Lee, Chang Eun Song, Taiho Park, Sang-Jin Moon, and Sora Oh
- Subjects
Flexibility (engineering) ,Fabrication ,Materials science ,Organic solar cell ,Renewable Energy, Sustainability and the Environment ,business.industry ,Photovoltaic system ,Intermolecular force ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Interconnectivity ,01 natural sciences ,Small molecule ,0104 chemical sciences ,Optoelectronics ,General Materials Science ,Fill factor ,0210 nano-technology ,business - Abstract
Solution-processed organic solar cells are promising owing to their light weight, ease of processability, low cost, flexibility, and large-area fabrication. Particularly, small-molecule active materials have been recently developed using straightforward synthesizing methods, exhibiting the least batch-to-batch variation in physical and optoelectronic properties and highly reproducible efficiency. A series of 2D-BDT-based active materials with various numbers of benzodithiophene (BDT) units and how the number of 2D-BDT units influences the construction of a well-defined interconnected structure are reported. The systematically controlled morphology of the 2D-BDT material helps achieve a high power-conversion efficiency (PCE) of 8.56% and a high fill factor of 0.73 without the use of additives. The reduced charge recombination and well-constructed morphology of this material facilitate a PCE of 7.45% in a 77.8 cm2 rigid module, which is the outstanding performance in large-area modules.
- Published
- 2016
25. Bandgap states in transition-metal (Sc, Y, Zr, and Nb)-doped Al2O3
- Author
-
Ranju Jung, Ye-Won So, Hyun-Joon Shin, Sora Oh, Jae-Cheol Lee, Jong-Cheol Lee, and Tae Won Noh
- Subjects
X-ray absorption spectroscopy ,Valence (chemistry) ,Materials science ,Physics and Astronomy (miscellaneous) ,X-ray photoelectron spectroscopy ,Absorption spectroscopy ,Photoemission spectroscopy ,Band gap ,Analytical chemistry ,Electronic structure ,Band offset - Abstract
We have investigated the electronic structure of transition-metal (TM=Sc, Y, Zr, and Nb)-doped Al2O3 by x-ray photoemission spectroscopy (XPS) and x-ray absorption spectroscopy (XAS). In valence bands of these TM-doped Al2O3 measured by XPS, the highest occupied levels and the shapes of valence bands are almost unchanged from the pure alumina. On the other hand, XAS spectra obtained at the oxygen K-edge show that Nb- and Zr-doped Al2O3 show localized d states in the bandgap below the conduction band minimum, while Y- and Sc-doped Al2O3 have d states inside the conduction band of the original Al2O3. This implies that Y- and Sc-doped Al2O3 will show little bandgap degradation and maintain the same band offset as silica at the Si interface, and can serve as promising candidates for an alternative gate oxide.
- Published
- 2003
26. Publisher's Note: Investigation of local symmetry effects on the electronic structure of manganites: HexagonalYMnO3versus orthorhombicLaMnO3[Phys. Rev. B79, 035116 (2009)]
- Author
-
Arata Tanaka, Sora Oh, Deok-Yong Cho, Dong Geun Kim, and J. H. Park
- Subjects
Physics ,Condensed matter physics ,Hexagonal crystal system ,Local symmetry ,Orthorhombic crystal system ,Electronic structure ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials - Published
- 2009
27. Curcumin inhibits osteoclastogenesis by decreasing receptor activator of nuclear factor-kappaB ligand (RANKL) in bone marrow stromal cells
- Author
-
Sora, Oh, Tae-Wook, Kyung, and Hye-Seon, Choi
- Subjects
Mice, Inbred C57BL ,Mice ,Curcumin ,Gene Expression Regulation ,Osteogenesis ,Interleukin-1alpha ,RANK Ligand ,Animals ,Osteoclasts ,Bone Marrow Cells ,Stromal Cells ,Coculture Techniques - Abstract
Curcumin (diferuloylmethane), a pigment derived from turmeric, has anti-oxidant and anti-inflammatory activities. Accumulating evidence points to a biochemical link between increased oxidative stress and reduced bone density. Osteoclast formation was evaluated in co-cultures of bone marrow stromal cells (BMSC) and whole bone marrow cells (BMC). Expression of receptor activator of nuclear factor-kappaB ligand (RANKL) was analyzed at the mRNA and protein levels. Exposure to curcumin led to dose-dependent suppression of osteoclastogenesis in the coculture system, and to reduced expression of RANKL in IL-1alpha-stimulated BMSCs. Addition of RANKL abolished the inhibition of osteoclastogenesis by curcumin, whereas the addition of prostaglandin E2(PGE2) did not. The decreased osteoclastogenesis induced by curcumin may reduce bone loss and be of potential benefit in preventing and/or attenuating osteoporosis.
- Published
- 2008
28. Erratum: Influence of oxygen vacancies on the electronic structure ofHfO2films [Phys. Rev. B76, 165411 (2007)]
- Author
-
J. Y. Kim, Sora Oh, Arata Tanaka, J. H. Park, Hoyoung Jang, Jae-Min Lee, and Deok-Yong Cho
- Subjects
Materials science ,chemistry ,Condensed matter physics ,chemistry.chemical_element ,Electronic structure ,Condensed Matter Physics ,Oxygen ,Electronic, Optical and Magnetic Materials - Published
- 2007
29. Performance of a Micro-Spot High-Resolution Photoemission Beamline at PAL
- Author
-
Jinhong Kim, Sora Oh, Deok-Yong Cho, Hyeong-Do Kim, Chul-Hee Min, Tai-Hee Kang, J. Y. Kim, and Bumjoon Kim
- Subjects
Physics ,business.industry ,Photoemission spectroscopy ,Resolution (electron density) ,Particle accelerator ,Grating ,law.invention ,Full width at half maximum ,Optics ,Beamline ,law ,Emission spectrum ,business ,Monochromator - Abstract
We present the commissioning results of a micro‐spot high‐resolution VUV & soft x‐ray photoemission beamline with a spherical grating monochromator at PAL. A negative‐order NOGARD‐type monochromator shows a good energy resolution enough for high‐resolution angle‐resolved photoemission spectroscopy, which is demonstrated by experimental photoabsorption spectra of various gases. The beam‐spot size at a sample position is estimated to be smaller than 10 × 10 μm2 (FWHM).
- Published
- 2007
30. Erratum: 'Control of silicidation in HfO2/Si(100) interfaces' [Appl. Phys. Lett. 86, 041913 (2005)]
- Author
-
Byung-Hoon Choi, Kee-Shik Park, Deok-Yong Cho, Y. J. Chang, Jae-Cheol Lee, Sora Oh, Sang Don Bu, Ranju Jung, Tae-Hee Noh, and Do-Hyoung Kim
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,Silicon ,chemistry ,business.industry ,Optoelectronics ,chemistry.chemical_element ,business ,Hafnium compounds - Published
- 2007
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