12 results on '"Sora Oh"'
Search Results
2. 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
- Subjects
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
3. Synthesis and Characterization of Benzodithiophene-4,8-Dione-Based Copolymers for Polymer Solar Cells
- Author
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Sora Oh, Taek Ahn, Da Hun Kim, and Sang Kyu Lee
- Subjects
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
4. 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
5. Simple and Versatile Non-Fullerene Acceptor Based on Benzothiadiazole and Rhodanine for Organic Solar Cells
- Author
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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
- Subjects
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
6. 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
7. 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
- Subjects
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
8. 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
- Subjects
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
9. 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
10. Chemical structure of the interface in ultrathin HfO2/Si films
- Author
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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
11. Erratum: Influence of oxygen vacancies on the electronic structure ofHfO2films [Phys. Rev. B76, 165411 (2007)]
- Author
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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
12. Erratum: 'Control of silicidation in HfO2/Si(100) interfaces' [Appl. Phys. Lett. 86, 041913 (2005)]
- Author
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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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