104 results on '"Jae Joon Lee"'
Search Results
2. Side-Chain Engineering of Diketopyrrolopyrrole-Based Hole-Transport Materials to Realize High-Efficiency Perovskite Solar Cells
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Mritunjaya Parashar, Jong Seung Kim, Amit Sharma, Jae-Joon Lee, Min Kim, Ranbir Singh, Manish Kumar, Ji Hyeon Kim, and Gururaj P. Kini
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Materials science ,Research areas ,business.industry ,Perovskite solar cell ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Side chain ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business ,Perovskite (structure) - Abstract
The design and synthesis of a stable and efficient hole-transport material (HTM) for perovskite solar cells (PSCs) are one of the most demanding research areas. At present, 2,2′,7,7′-tetrakis[N,N-d...
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- 2021
3. A tailored graft-type polymer as a dopant-free hole transport material in indoor perovskite photovoltaics
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Se-Woong Baek, Hyungju Ahn, Jea Woong Jo, Jae-Joon Lee, Ji Hyeon Lee, Henry Opoku, and Yun Hoo Kim
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chemistry.chemical_classification ,Electron mobility ,Materials science ,Passivation ,Dopant ,Renewable Energy, Sustainability and the Environment ,business.industry ,02 engineering and technology ,General Chemistry ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Chemical engineering ,chemistry ,Photovoltaics ,Side chain ,General Materials Science ,0210 nano-technology ,business ,Ethylene glycol ,Perovskite (structure) - Abstract
As an essential component in efficient perovskite photovoltaics (PPVs), hole transport materials (HTMs) that meet the intricate requirements for next-generation charge transport layers have recently been of immense interest. Specifically, functionally tailored HTMs that aid in mitigating charge transport limitations and interfacial defects and thereby enhance the performance of both indoor and outdoor PPVs are being sought after. Herein, we developed a novel graft-type polymer composed of a benzo[1,2-b:4,5:b′]dithiophene-based main chain and poly(ethylene glycol) (PEG) side chains as an efficient dopant-free HTM for PPVs. Through a systemized tailoring of the contents of the side chains, we were able to control the hole transport and interfacial passivation abilities of the graft-type polymeric HTM. The polymeric HTM with an optimized PEG side chain exhibited a higher hole mobility, a reduced amount of interfacial traps, and an enhanced device stability compared to the control polymeric HTM. The PPVs capped with the optimized graft-type polymeric HTM demonstrated remarkably high power conversion efficiencies up to 38.2% and 21.7% under 1000 lux LED and AM 1.5 solar illuminations, respectively.
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- 2021
4. Trimethylsulfonium lead triiodide (TMSPbI3) for moisture-stable perovskite solar cells
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Md. Mahbubur Rahman, Sanjay Sandhu, Chuangye Ge, Kicheon Yoo, Sunghwan Kim, Ranbir Singh, Arif Ahmed, and Jae-Joon Lee
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chemistry.chemical_classification ,Materials science ,Renewable Energy, Sustainability and the Environment ,Band gap ,Sulfonium ,Iodide ,Analytical chemistry ,Energy Engineering and Power Technology ,02 engineering and technology ,Crystal structure ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Trimethylsulfonium ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Fuel Technology ,Formamidinium ,chemistry ,Triiodide ,0210 nano-technology ,Perovskite (structure) - Abstract
Conventional, high-efficiency, hybrid organic–inorganic perovskites (e.g., methylammonium lead iodide (MAPbI3) and formamidinium lead iodide (FAPbI3)) having ammonium-based organic cations exhibit poor moisture stability mainly due to the effective hydrogen bonding interaction of nitrogen in the ammonium-based cations with water molecules. Recently, a sulfonium-based cation, trimethylsulfonium (TMS+), has attracted growing attention for the development of moisture-stable hybrid perovskite solar cells (PSCs). This research investigated the photovoltaic performance of trimethylsulfonium lead triiodide (TMSPbI3) based PSCs and their moisture stability both experimentally and theoretically. The results revealed that TMSPbI3 exhibited a relatively large optical band gap (Eg = 2.32 eV) and high absorption coefficient (α = 2.30 × 104 cm−1 at 500 nm) with a hexagonal one-dimensional crystal structure. The PSCs with a device structure of FTO/c-TiO2/m-TiO2/TMSPbI3/CuSCN/Au exhibited a power conversion efficiency (PCE) of 2.22% with no hysteresis in the I–V curve, and high moisture stability at ambient temperature (25 ± 3 °C, ca. 50% relative humidity) with a PCE loss of only ca. 4.6% after 500 h. This result could be attributed to the absence of the hydrogen bonding interaction of TMS+ with water molecules, leading to the effective stabilization of TMSPbI3 compared to MAPbI3 and FAPbI3, verified by density functional theory calculations.
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- 2021
5. Effect of residual electrolyte on dispersion stability of graphene in aqueous solution
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Jongdeok Park, Chan Hee Lee, Hemraj M. Yadav, Sae Youn Lee, and Jae-Joon Lee
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Aqueous solution ,Materials science ,Graphene ,02 engineering and technology ,Electrolyte ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Residual ,Electrochemistry ,01 natural sciences ,0104 chemical sciences ,law.invention ,Chemical engineering ,law ,Dispersion stability ,General Materials Science ,Graphite ,Electrical and Electronic Engineering ,0210 nano-technology ,Dispersion (chemistry) - Abstract
The stability of graphene dispersions in water is of both scientific and technological significance. We studied the dispersion stability of electrochemically exfoliated graphene in an aqueous medium to minimize the strong aggregation tendency, within a short period, of graphene prepared in various electrolytes. This study focused on increasing the dispersion stability of graphene and finding the reason for its poor dispersion stability. The residual electrolyte trapped in the graphene layers was difficult to be removed from electrochemically exfoliated graphite and caused a significant aggregation. The stability and dispersion concentration can be improved by removing the trace amount of aqueous electrolyte. The aggregation mechanism of graphene in aqueous media is proposed and discussed in detail.
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- 2020
6. Cross-conjugated BODIPY pigment for highly efficient dye sensitized solar cells
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Ryuji Kaneko, Anas Ahmed, M. Abdel-Shakour, Jae-Joon Lee, Antoine Mirloup, Faiz Shah, Abdulkader S. Hanbazazah, Nicolas Leclerc, Ashraful Islam, Alexandra Sutter, Towhid H. Chowdhury, University of Jeddah (University of Jeddah), Institut de chimie et procédés pour l'énergie, l'environnement et la santé (ICPEES), Université de Strasbourg (UNISTRA)-Matériaux et nanosciences d'Alsace (FMNGE), and Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
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Materials science ,Renewable Energy, Sustainability and the Environment ,Energy conversion efficiency ,Energy Engineering and Power Technology ,02 engineering and technology ,Conjugated system ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,7. Clean energy ,0104 chemical sciences ,chemistry.chemical_compound ,Pigment ,Dye-sensitized solar cell ,Fuel Technology ,chemistry ,visual_art ,visual_art.visual_art_medium ,[CHIM]Chemical Sciences ,Surface modification ,BODIPY ,0210 nano-technology ,ComputingMilieux_MISCELLANEOUS - Abstract
In this study, we report a new BODIPY-based design, called the cross-conjugated design, that takes advantage of the α- and β-position functionalization of the BODIPY core. After synthesis, and compared to a more standard BODIPY dye, using similar functional groups and based on a horizontal design, called h-BOD, the new cross-conjugated BODIPY dye (cc-BOD) exhibits clearly the highest conjugation and light harvesting properties. Consequently, when used as photosensitizers in dye-sensitized solar cells (DSSCs), an impressive improvement of power conversion efficiency (PCE) has been observed, with a PCE of 6.02% with broad incident photon to current conversion efficiency (IPCE) for cc-BOD, compared to only 3.7% for h-BOD. Moreover, by co-sensitizing a DSSC with the two complementary absorbing dyes h-BOD and cc-BOD, we further improved the PCE up to 6.2%.
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- 2020
7. Standardizing Performance Measurement of Dye-Sensitized Solar Cells for Indoor Light Harvesting
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Jae Won Shim, Swarup Biswas, Kicheon Yoo, Sang-Chul Shin, Kyu-Jin Kim, Yongju Lee, Hyeok Kim, and Jae-Joon Lee
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Working electrode ,General Computer Science ,Irradiance ,02 engineering and technology ,Indoor dye sensitize photovoltaic ,010402 general chemistry ,01 natural sciences ,Luminance ,law.invention ,law ,General Materials Science ,Performance measurement ,business.industry ,luminance ,System of measurement ,Photovoltaic system ,General Engineering ,different source of indoor light ,021001 nanoscience & nanotechnology ,irradiance power intensity ,diffused light ,0104 chemical sciences ,Dye-sensitized solar cell ,Optoelectronics ,Environmental science ,Cold cathode ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,maximum output power density ,0210 nano-technology ,business ,lcsh:TK1-9971 - Abstract
During the last five years the demand of indoor photovoltaic (IPV) technology is growing rapidly for the Internet of Things. Until now, there is no standardized measurement methodology for IPV devices. So, it is very hard to estimate device efficiency accurately in indoor illuminating condition. This is one of the main obstacles for the commercialization of IPV devices. A standardized universal measurement methodology is highly needed. Therefore in this study, a series of N719 dye based dye-sensitized photovoltaic (PV) cells have been fabricated by varying the working electrode thickness. Then, a low irradiance measurement system has been configured to develop an ideal indoor environment with diffused light by adjusting the distance (1.4 m) between the test cell and light source. Furthermore, the inner wall of the measurement system has been covered by white paper. PV cells are tested under the illumination of three different light sources such as cold cathode fluorescent lamp (CCFL), cool white LED (LED 5600 K), and warm white LED (LED 3200 K)), at the same irradiance power intensity (150 μW/cm2) and luminance (500 Lux) values, to standardize the measurement methodology for PV cells in indoor environment. This study shows that, the response of a PV cell to different light sources can be realized more accurately, if the PV cell is tested under the illumination of different light sources at a fixed irradiance power intensity value instead of a fixed luminance value.
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- 2020
8. Role of electrolyte at the interface and in the dispersion of graphene in organic solvents
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Sae Youn Lee, Jae-Joon Lee, Muhammad Mohsin Hossain, and Hemraj M. Yadav
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010302 applied physics ,Range (particle radiation) ,Materials science ,Graphene ,Electrolyte ,Condensed Matter Physics ,Electrochemistry ,01 natural sciences ,Exfoliation joint ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Ion ,law.invention ,Chemical engineering ,law ,0103 physical sciences ,Dispersion stability ,Electrical and Electronic Engineering ,Dispersion (chemistry) - Abstract
The electrochemical exfoliation of graphene is a very useful technique to prepare highly conductive graphene with a low defect level. However, low dispersion stability is a barrier to this process being used to prepare graphene directly in a wide range of applications. Even though the dispersion stability and concentration of graphene are important, the reasons for the lower dispersion stability and lower concentration of electrochemically exfoliated graphene have not yet been clarified. In this study, we identified that the strong electrostatic attractive interaction between charged ions from electrolytes at the interfaces of graphene layers substantially deteriorated the dispersion stability. Both the stability and the concentration of graphene dispersions were substantially enhanced upon removal of the residual electrolytes from the organic solvents used in this study.
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- 2019
9. V899 Mon: a peculiar eruptive young star close to the end of its outburst
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Sunkyung Park, Ágnes Kóspál, Fernando Cruz-Sáenz de Miera, Michał Siwak, Marek Dróżdż, Bernadett Ignácz, Daniel T. Jaffe, Réka Könyves-Tóth, Levente Kriskovics, Jae-Joon Lee, Jeong-Eun Lee, Gregory N. Mace, Waldemar Ogłoza, András Pál, Stephen B. Potter, Zsófia Marianna Szabó, Ramotholo Sefako, and Hannah L. Worters
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Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,010309 optics ,Astrophysics - Solar and Stellar Astrophysics ,13. Climate action ,Space and Planetary Science ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics - Abstract
V899 Mon is an eruptive young star showing characteristics of both FUors and EXors. It reached a peak brightness in 2010, then briefly faded in 2011, followed by a second outburst. We conducted multi-filter optical photometric monitoring, as well as optical and near-infrared spectroscopic observations of V899 Mon. The light curves and color-magnitude diagrams show that V899 Mon has been gradually fading after its second outburst peak in 2018, but smaller accretion bursts are still happening. Our spectroscopic observations taken with Gemini/IGRINS and VLT/MUSE show a number of emission lines, unlike during the outbursting stage. We used the emission line fluxes to estimate the accretion rate and found that it has significantly decreased compared to the outbursting stage. The mass loss rate is also weakening. Our 2D spectro-astrometric analysis of emission lines recovered jet and disk emission of V899 Mon. We found the emission from permitted metallic lines and the CO bandheads can be modeled well with a disk in Keplerian rotation, which also gives a tight constraint for the dynamical stellar mass of 2 ${M_{\odot}}$. After a discussion of the physical changes that led to the changes in the observed properties of V899 Mon, we suggest this object is finishing its second outburst., 31 pages, 26 figures, accepted for publication in ApJ
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- 2021
10. Preliminary Investigation on Vacancy Filling by Small Molecules on the Performance of Dye-Sensitized Solar Cells: The Case of a Type-II Absorber
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Jae-Joon Lee, Kicheon Yoo, Nguyen Huy Hao, Ashok Kumar Kaliamurthy, Hyeong Cheol Kang, and Francis Kwaku Asiam
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Steric effects ,Materials science ,dye-sensitized solar cells and thermodynamics ,vacancy ,02 engineering and technology ,Substrate (electronics) ,010402 general chemistry ,Photochemistry ,Branching (polymer chemistry) ,01 natural sciences ,chemistry.chemical_compound ,Adsorption ,Z907 ,Vacancy defect ,co-sensitization ,QD1-999 ,Original Research ,Catechol ,General Chemistry ,catechol ,021001 nanoscience & nanotechnology ,Small molecule ,0104 chemical sciences ,Chemistry ,Dye-sensitized solar cell ,chemistry ,0210 nano-technology - Abstract
The steric shielding offered by sensitizers on semiconducting surfaces as a result of branching in the dyes used offers the less utilization of semiconducting substrate sites during device fabrication in dye-sensitized solar cells (DSSCs). This work proposes a strategy to increase the coverage through the utilization of small molecules which have the ability to penetrate into the sites. The small molecules play the dual role of vacancy filling and sensitization, which can be viewed as an alternative to co-sensitization also. Hence, we show for the first time ever that the co-adsorption of catechol with Z907 as a sensitizer enhances the electron density in the photo-anode by adsorbing on the vacant sites. Catechol was subsequently adsorbed on TiO2 after Z907 as it has a stronger interaction with TiO2 owing to its favorable thermodynamics. The reduced number of vacant sites, suppressed charge recombination, and enhanced spectral response are responsible for the improvement in the PCEs. Quantitatively, both organic and aqueous electrolytes were used and the co-sensitized DSSCs had PCE enhancements of 7.2 and 60%, respectively, compared to the control devices.
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- 2021
11. Evidence of Accretion Burst: The Viscously Heated Inner Disk of the Embedded Protostar IRAS 16316-1540
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Sung-Yong Yoon, Daniel T. Jaffe, Gregory N. Mace, Gregory J. Herczeg, Seokho Lee, Jae-Joon Lee, Jeong-Eun Lee, and Sunkyung Park
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Physics ,010308 nuclear & particles physics ,Young stellar object ,Astrophysics::High Energy Astrophysical Phenomena ,Continuum (design consultancy) ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Accretion (astrophysics) ,Spectral line ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,13. Climate action ,Space and Planetary Science ,0103 physical sciences ,Thick disk ,Protostar ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics ,Line (formation) - Abstract
Outbursts of young stellar objects occur when the mass accretion rate suddenly increases. However, such outbursts are difficult to detect for deeply embedded protostars due to their thick envelope and the rarity of outbursts. The near-IR spectroscopy is a useful tool to identify ongoing outburst candidates by the characteristic absorption features that indicate a disk origin. However, without high-resolution spectroscopy, the spectra of outburst candidates can be confused with the late-type stars since they have similar spectral features. For the protostar IRAS 16316-1540, the near-IR spectrum has line equivalent widths that are consistent with M-dwarf photospheres. However, our high-resolution IGRINS spectra reveal that the absorption lines have boxy and/or double-peaked profiles, as expected from a disk and not the star. The continuum emission source is likely the hot, optically thick disk, heated by viscous accretion. The projected disk rotation velocity of 41$\pm$5 km s$^{-1}$ corresponds to $\sim 0.1$ AU. Based on the result, we suggest IRAS 16316-1540 as an ongoing outburst candidate. Viscous heating of disks is usually interpreted as evidence for ongoing bursts, which may be more common than previously estimated from low-resolution near-IR spectra., 13 pages, 6 figures, Accepted for publication in ApJ
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- 2021
12. High-resolution Near-infrared Spectroscopy of Diffuse Sources around MWC 1080
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Tae-Soo Pyo, Kwang-Il Seon, Woong-Seob Jeong, Il-Joong Kim, Jae-Joon Lee, and Heeyoung Oh
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Physics ,010504 meteorology & atmospheric sciences ,Infrared ,Near-infrared spectroscopy ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,01 natural sciences ,Astrophysics - Astrophysics of Galaxies ,Interstellar medium ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,0103 physical sciences ,Outflow ,Emission spectrum ,Herbig–Haro object ,85-11 ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,0105 earth and related environmental sciences ,Line (formation) - Abstract
To reveal the origins of diffuse H-alpha emissions observed around the Herbig star MWC 1080, we have performed a high-resolution near-infrared (NIR) spectroscopic observation using the Immersion GRating INfrared Spectrograph (IGRINS). In the NIR H and K bands, we detected various emission lines (six hydrogen Brackett lines, seven H2 lines, and an [Fe II] line) and compared their spatial locations with the optical (H-alpha and [S II]) and radio (13CO and CS) line maps. The shock-induced H2 and [Fe II] lines indicate the presence of multiple outflows, consisting of at least three, associated young stars in this region. The kinematics of H2 and [Fe II] near the northeast (NE) cavity edge supports that the NE main outflow from MWC 1080A is the blueshifted one with a low inclination angle. The H2 and [Fe II] lines near the southeast molecular region newly reveal that additional highly-blueshifted outflows originate from other young stars. The fluorescent H2 lines were found to trace photodissociation regions formed on the cylindrical surfaces of the main outflow cavity, which are expanding outward with a velocity of about 10-15 km/s. For the H-alpha emission, we identify its components associated with two stellar outflows and two young stars in addition to the dominant component of MWC 1080A scattered by dust. We also report a few faint H-alpha features located ~0.4 pc away in the southwest direction from MWC 1080A, which lie near the axes of the NE main outflow and one of the newly-identified outflows., 29 pages, 14 figures, 4 tables; accepted for publication in AJ
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- 2021
13. Photoluminescent Metal Complexes and Materials as Temperature Sensors—An Introductory Review
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Jae Joon Lee and John W. Kenney
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Materials science ,Photoluminescence ,02 engineering and technology ,QD415-436 ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Engineering physics ,Biochemistry ,thermometer ,0104 chemical sciences ,Analytical Chemistry ,non-contact ,phosphorescence ,sensor ,Thermometer ,luminescence ,fluorescence ,Physical and Theoretical Chemistry ,0210 nano-technology ,Luminescence ,Physical quantity - Abstract
Temperature is a fundamental physical quantity whose accurate measurement is of critical importance in virtually every area of science, engineering, and biomedicine. Temperature can be measured in many ways. In this pedagogically focused review, we briefly discuss various standard contact thermometry measurement techniques. We introduce and touch upon the necessity of non-contact thermometry, particularly for systems in extreme environments and/or in rapid motion, and how luminescence thermometry can be a solution to this need. We review the various aspects of luminescence thermometry, including different types of luminescence measurements and the numerous materials used as luminescence sensors. We end the article by highlighting other physical quantities that can be measured by luminescence (e.g., pressure, electric field strength, magnetic field strength), and provide a brief overview of applications of luminescence thermometry in biomedicine.
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- 2021
14. Binary redox electrolytes used in dye-sensitized solar cells
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Jae-Joon Lee and Narayan Chandra Deb Nath
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Materials science ,Open-circuit voltage ,business.industry ,General Chemical Engineering ,Fermi level ,Energy conversion efficiency ,02 engineering and technology ,Electrolyte ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Redox ,0104 chemical sciences ,Dye-sensitized solar cell ,symbols.namesake ,symbols ,Optoelectronics ,0210 nano-technology ,business ,Absorption (electromagnetic radiation) ,Visible spectrum - Abstract
Fast dye-regeneration and slow charge recombination are prerequisites for selecting superior redox couples of electrolytes to obtain highly efficient dye-sensitized solar cells (DSSCs). Although the ubiquitous combination of the I−/I3− redox couple demonstrates high power conversion efficiency (PCE), it suffers from several limitations such as a large potential difference of approximately 560 mV between the Fermi level of I−/I3− and the HOMO level of the N719 dye as well as high visible light absorption. These limitations cause inefficient dye-regeneration and significantly enhance the back reaction rate of photoelectrons to I3− in the electrolyte. This review discusses recent progress in the conception and device performance of different binary redox couples in DSSCs based on lowering potential differences, the back reaction of photo-induced electrons, the absorption of visible light, and improvement of dye-regeneration. We specifically focus on recent strategies targeted for effectively increasing both the open circuit voltage of DSSCs up to ˜100 mV and the PCE to above 10%; these strategies include introduction of binary redox couples or additional redox species to conventional iodine-based electrolytes. Moreover, we propose future directions for the further development of binary redox couples with advanced concepts for achieving DSSCs with high performance and high stability.
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- 2019
15. Stable Triple-Cation (Cs+–MA+–FA+) Perovskite Powder Formation under Ambient Conditions for Hysteresis-Free High-Efficiency Solar Cells
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Ranbir Singh, Hemraj M. Yadav, Jae-Joon Lee, and Sanjay Sandhu
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Materials science ,Chemical substance ,Photovoltaic system ,Halide ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,law.invention ,Hysteresis ,Chemical engineering ,law ,Solar cell ,General Materials Science ,Thermal stability ,0210 nano-technology ,Science, technology and society ,Perovskite (structure) - Abstract
Organometallic halide perovskite materials have promising photovoltaic properties and emerged as a cost-effective solar cell technology. However, a synthesis protocol to fabricate high-quality pero...
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- 2019
16. Evolution of Pb-Free and Partially Pb-Substituted Perovskite Absorbers for Efficient Perovskite Solar Cells
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Mohd. Aizat Abdul Wadi, Idriss Bedja, Jae-Joon Lee, Towhid H. Chowdhury, Ashraful Islam, Aktharuzzaman, and Nowshad Amin
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Materials science ,Low toxicity ,Photovoltaic system ,Energy conversion efficiency ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Chemical engineering ,Divalent metal ions ,Degradation (geology) ,0210 nano-technology ,Perovskite (structure) - Abstract
Announced as one of the top 10 research breakthroughs in 2016, perovskite solar cells (PSC) have advanced rapidly as an established photovoltaic technology. The power conversion efficiency (PCE) of PSCs has increased quickly from 3.8% to 23.7% within a period of just 7 years. This very high PCE has been achieved by using perovskite compounds with lead (Pb) as the divalent metal ion. However, for further scale-up and commercialization, the toxicity of Pb has been identified as one of the key drawbacks for this technology. Numerous avenues for development of lead-free low-toxicity perovskite absorbers have been pursued. The unclear effect of using low-toxicity materials on optimal performance with suitable characteristics has motivated the writing of this review. Results from low-toxicity perovskite solar cells utilizing partial or complete substitution of the Pb2+ cation as the absorber layer are discussed in detail. Moreover, we discuss the limitations of low-toxicity absorber materials. This review summarizes the key points of film quality control, degradation effect, Pb replacement suitability, and photovoltaic performance of reported low toxicity alternate perovskite absorbers for PSCs.
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- 2019
17. Ternary Blend Strategy for Achieving High‐Efficiency Organic Photovoltaic Devices for Indoor Applications
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Hansol Lee, Sang-Chul Shin, Ranbir Singh, Jae Won Shim, Jae-Joon Lee, Kilwon Cho, and Min Kim
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010405 organic chemistry ,Organic Chemistry ,Energy conversion efficiency ,General Chemistry ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,Crystallinity ,chemistry ,Chemical engineering ,Diimide ,Thin film ,Absorption (electromagnetic radiation) ,Ternary operation ,Perylene - Abstract
Monomeric perylene diimide (PDI) small molecules display a high absorption coefficient and crystallinity in solid-state thin films due to strong π-π interactions between the molecules. To take advantage of these exciting properties of PDIs, N,N'-bis(1-ethylpropyl)perylene-3,4,9,10-tetracarboxylic diimide (EP-PDI) was mixed with a binary blend of PTB7 and PC71 BM to fabricate an efficient ternary blend, which were in turn used to produce organic photovoltaic (OPV) devices well suited to indoor applications (PTB7=poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}), PC71 BM=[6,6]-phenyl-C71 -butyric acid methyl ester). We varied the PC71 BM/EP-PDI weight ratio to investigate the influence of EP-PDI on the optical, electrical, and morphological properties of the PTB7:PC71 BM:EP-PDI ternary blend. Compared with the reference PTB7:PC71 BM binary blend, the ternary blends showed strong optical absorption in the wavelength range in which the spectra of indoor LED lamps show their strongest peaks. The addition of EP-PDI to the binary blend was found to play an important role in altering the morphology of the blend in such a way as to facilitate charge transport in the resulting ternary blend. Apparently, as a result, the optimal PTB7:PC71 BM:EP-PDI-based inverted OPV device exhibited a power conversion efficiency (PCE) of 15.68 %, a fill factor (FF) of 68.5 %, and short-circuit current density (JSC ) of 56.7 μA cm-2 under 500 lx (ca. 0.17 mW cm-2 ) indoor LED light conditions.
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- 2019
18. Quaternary indoor organic photovoltaic device demonstrating panchromatic absorption and power conversion efficiency of 10%
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Jae Won Shim, Sang-Chul Shin, Premkumar Vincent, Hyeok Kim, Doo-Hyun Ko, Minwoo Nam, Jae-Joon Lee, and Jin-Hyuk Bae
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Materials science ,Equivalent series resistance ,business.industry ,Process Chemistry and Technology ,General Chemical Engineering ,Photovoltaic system ,Energy conversion efficiency ,Heterojunction ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,law.invention ,Photovoltaics ,law ,Solar cell ,Optoelectronics ,0210 nano-technology ,Absorption (electromagnetic radiation) ,business ,Ternary operation - Abstract
Recently, while increasing research has been focused toward improving the efficiency of various photovoltaic devices under low light intensities, few studies have reported on multi-donor-, multi-acceptor-based bulk heterojunctions (BHJ). In this study, we have demonstrated the utilization of a quaternary BHJ for indoor light energy harvesting applications. We utilized a PCDTBT:PTB7:PC61BM:PC71BM-based BHJ structure in order to improve the morphology, absorption window, and the charge transport properties of the photovoltaic device. The ability of ternary photovoltaics to attain high power-conversion efficiency (PCE) by improving the morphology and the charge transport properties had already been validated in another study. We show that the advantages of a stable quaternary solar cell can also be achieved with an optimized BHJ composition ratio of 5:5:3:12, which provides a PCE of 10.6%. Our device showed high shunt resistance and low series resistance, thus facilitating appreciable charge extraction even under low-intensity light conditions such as 500 lx white LED illumination.
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- 2019
19. Ultra-thick semi-crystalline photoactive donor polymer for efficient indoor organic photovoltaics
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Hyeok Kim, Ji Soo Goo, Premkumar Vincent, Chang Woo Koh, Sang-Chul Shin, Jae Won Shim, Jin-Hyuk Bae, Changhwan Shin, Jae-Joon Lee, and Han Young Woo
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Materials science ,Organic solar cell ,Renewable Energy, Sustainability and the Environment ,business.industry ,Energy conversion efficiency ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Active layer ,law.invention ,Photoactive layer ,Halogen lamp ,law ,Parasitic element ,Optoelectronics ,General Materials Science ,Electrical and Electronic Engineering ,0210 nano-technology ,business ,Absorption (electromagnetic radiation) ,Power density - Abstract
An in-depth study on the photovoltaic characteristics under indoor lights, i.e., light-emitting diode (LED), fluorescent lamps, and halogen lamps, was performed with varying the photoactive layer thickness (120–870 nm), by comparing those under 1-sun condition. The semi-crystalline mid-gap photoactive polymer, poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole)] (PPDT2FBT) and a fullerene derivative, [6,6]-phenyl C71 butyric acid methyl ester (PC70BM) were used as a photoactive layer. In the contrary to the measurements under 1-sun condition, the indoor devices show a clearly different behavior, showing the thickness tolerant short-circuit current density (JSC) and fill factor (FF) values with 280–870 nm thick photoactive layers. The retained JSC and FF values of thick indoor devices were discussed in terms of the parasitic resistance effects based on the single-diode equivalent circuit model. The much lower series/shunt resistance (Rs/RP) ratio was measured with thick photoactive layer (≥280 nm), resulting in negligible decreases in the JSC and FF values even with a 870-nm-thick active layer under the LED condition. Under 1000 lx LED light, the PPDT2FBT:PC70BM device showed an optimum power conversion efficiency (PCE) of 16% (max power density, 44.8 μW/cm2) with an open-circuit voltage of 587 mV, a JSC of 117 μA/cm2, and a FF of 65.2. The device with a 870-nm-thick active layer still exhibited an excellent performance with a PCE of 12.5%. These results clearly suggest that the critical parasitic resistance effects on the performance vary depending on the light illumination condition, and the large RP associated with the viable thick photoactive layer and the well-matched absorption (of photoactive layer) with the irradiance spectrum (of indoor light) are essential to realize efficient indoor photovoltaic cells with high JSC and FF.
- Published
- 2019
20. Solvothermal growth of 3D flower-like CoS@FTO as high-performance counter electrode for dye-sensitized solar cell
- Author
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Kicheon Yoo, Sajid Ali Ansari, Muhammad Adeel, Jae-Joon Lee, and Hemraj M. Yadav
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Auxiliary electrode ,Materials science ,endocrine system diseases ,engineering.material ,01 natural sciences ,law.invention ,chemistry.chemical_compound ,Coating ,law ,0103 physical sciences ,Solar cell ,Electrical and Electronic Engineering ,010302 applied physics ,nutritional and metabolic diseases ,Substrate (chemistry) ,pathological conditions, signs and symptoms ,Condensed Matter Physics ,Tin oxide ,Cobalt sulfide ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Dye-sensitized solar cell ,chemistry ,Chemical engineering ,engineering ,Adhesive - Abstract
In this work, a simple and one-step solvothermal method has been developed for directly growing three-dimensional flower-like cobalt sulfide (CoS) on the fluorine-doped tin oxide coated glass substrate (FTO) for the counter electrode in the dye sensitized solar cell. The electroctalytic activity of the CoS@FTO towards the I3− to I− reduction exhibited almost similar electrocatalytic properties to the Pt-based counter electrode. The dye-sensitized solar cell (DSSC) assembled with CoS@FTO counter electrode attained almost similar photovoltaic performance (5.64%) to that of the DSSC with Pt@FTO counter electrode (5.9%) under 1 sun illumination. The adhesion stability of the CoS deposited at FTO was also studied using strong adhesive tape test, and the results show that after the strong adhesive tape test, the CoS@FTO retained almost 95% of the coating. The similar and comparative performance of the CoS@FTO to the Pt@FTO may be due to the high surface area originating from the 3D flower-like morphology, and the excellent electrocatalytic activity of the CoS.
- Published
- 2019
21. Edge-carboxylated graphene nanoplatelets as efficient electrode materials for electrochemical supercapacitors
- Author
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Sajid Ali Ansari, Jae-Joon Lee, In-Yup Jeon, Narayan Chandra Deb Nath, Jong-Beom Baek, and Myung Jong Ju
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Materials science ,Graphene ,Diffusion ,02 engineering and technology ,General Chemistry ,Electrolyte ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Capacitance ,0104 chemical sciences ,law.invention ,Chemical engineering ,law ,General Materials Science ,Graphite ,Wetting ,0210 nano-technology ,Ball mill ,Current density - Abstract
Edge-carboxylated graphene nanoplatelets (ECG), prepared by a mechano-chemical reaction (or ball milling method) in the presence of dry ice, are eligible for an efficient electrode materials for electrochemical supercapacitors. ECG contained a higher content of edge-carboxylic groups with less structural defects, compared with the nitrogen-doped carboxylic graphene (NGOOH) prepared from the conventional solution-exfoliation of graphite. The structural defects level of ECG is ca. 16.2%, while it was ca. 48.9% for NGOOH. The edge-carboxylation increases the electroactive surface area, hydrophilicity and wettability of graphene without serious deterioration of the intrinsic properties e.g., chemical, mechanical and electronic properties. In result, it is more effective in enabling ion adsorption and rapid electrolyte diffusion within the pores of graphene which results in a significant increase of specific capacitance (Csp) to 365.72 F/g at a current density of 1 A/g, with a good charge–discharge property and rate capability for ECG. On the other hand, the Csp significantly decreases to ca. 175.05 F/g for NGOOH, as its high level of structural defects seriously affected its electronic properties.
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- 2019
22. Label-free aptasensor for the detection of cardiac biomarker myoglobin based on gold nanoparticles decorated boron nitride nanosheets
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Md. Mahbubur Rahman, Jae-Joon Lee, and Muhammad Adeel
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Boron Compounds ,Materials science ,Point-of-Care Systems ,Aptamer ,Biomedical Engineering ,Biophysics ,Metal Nanoparticles ,Biosensing Techniques ,02 engineering and technology ,Electrochemistry ,01 natural sciences ,chemistry.chemical_compound ,Limit of Detection ,Humans ,Detection limit ,Myoglobin ,010401 analytical chemistry ,Electrochemical Techniques ,General Medicine ,Aptamers, Nucleotide ,021001 nanoscience & nanotechnology ,Tin oxide ,Nanostructures ,0104 chemical sciences ,Chemical engineering ,chemistry ,Boron nitride ,Colloidal gold ,Electrode ,Gold ,0210 nano-technology ,Biosensor ,Biotechnology - Abstract
A novel electrochemical aptasensor based on gold nanoparticles decorated on boron nitride nanosheets (AuNPs/BNNSs) for the sensitive and selective detection of myoglobin (Mb) is reported. BNNSs were chemically synthesized by a low-cost and simple hydrothermal method. They were deposited onto the fluorine-doped tin oxide (FTO) electrode by a spin-coating method. Subsequently, AuNPs were chemically deposited onto the BNNS/FTO electrode by a seed-mediated chemical reduction method, with an average particle size of approximately 10 nm. The AuNPs/BNNSs/FTO electrode was used as a transducer to immobilize a thiol-functionalized DNA aptamer (Apt) via the covalent interaction of Au–S for the specific binding of Mb. [Fe(CN)6]3-/4- was used as a redox probe to monitor the oxidation current variation upon the binding of Mb with varying concentrations onto the sensor surface. The Apt/AuNPs/BNNSs/FTO sensor shows a high signal response for Mb with a detection limit of 34.6 ng/mL and a dynamic response range of 0.1–100 µg/mL. It is a promising candidate for point-of-care diagnosis in real samples. This strategy could make possible the application of other 2D materials with wide bandgaps for the development of biosensors.
- Published
- 2019
23. Coadditive Engineering with 5-Ammonium Valeric Acid Iodide for Efficient and Stable Sn Perovskite Solar Cells
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Jae-Joon Lee, Ashraful Islam, Ryuji Kaneko, Takeshi Noda, Md. Emrul Kayesh, Kiyoto Matsuishi, and Said Kazaoui
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chemistry.chemical_classification ,Materials science ,Valeric acid ,Renewable Energy, Sustainability and the Environment ,Hydrogen bond ,Energy conversion efficiency ,Iodide ,Energy Engineering and Power Technology ,Crystal growth ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Fuel Technology ,chemistry ,Octahedron ,Chemical engineering ,Chemistry (miscellaneous) ,Materials Chemistry ,SN2 reaction ,0210 nano-technology ,Perovskite (structure) - Abstract
Sn-based perovskite solar cells (PSCs) featuring high performance and long-term stability are very challenging because Sn2+ is relatively prone to oxidation. Here, we have performed coadditive engineering with 5-ammonium valeric acid iodide (5-AVAI) for FASnI3-based perovskite films. From the morphological, structural, and elemental analyses, we observed that 5-AVAI affects the crystal growth of perovskites through its hydrogen bond with I– of the SnI64– octahedral. As a result, pinhole-free homogeneous and stable Sn-based perovskite films form over a large area with lower Sn4+ content. This made us able to enhance the power conversion efficiency (PCE) for Sn-based PSCs up to 7% in a 0.25 cm2 aperture area. Most importantly, the 5-AVAI added PSCs showed a record stability and maintained their initial PCE under 1 sun continuous illumination at maximum power point tracking for 100 h.
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- 2018
24. Highly Stable All-Inorganic Pb-Free Perovskite Solar Cells
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Jin Hyuck Heo, Nang Mya Su Aung, Jae-Joon Lee, Min-Ho Lee, Dae Ho Song, Sang Hyuk Im, Chang Eun Song, and Ki-Ha Hong
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Materials science ,Inorganic chemistry ,02 engineering and technology ,Electrical and Electronic Engineering ,010402 general chemistry ,021001 nanoscience & nanotechnology ,0210 nano-technology ,01 natural sciences ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Perovskite (structure) - Published
- 2018
25. One-pot synthesis of copper nanoparticles on glass: applications for non-enzymatic glucose detection and catalytic reduction of 4-nitrophenol
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Jae-Joon Lee and Hemraj M. Yadav
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Materials science ,Reducing agent ,One-pot synthesis ,Nanoparticle ,Substrate (chemistry) ,chemistry.chemical_element ,4-Nitrophenol ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Electrochemistry ,01 natural sciences ,Copper ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,chemistry ,General Materials Science ,Electrical and Electronic Engineering ,0210 nano-technology ,Nuclear chemistry - Abstract
Thin film of metallic Cu nanoparticles was synthesized by a one-pot chemical reduction method at ambient temperature. Cu(II) acetate monohydrate and hydrazine monohydrate were used as precursor and reducing agent without additional surfactants to form uniform layer of Cu nanoparticle layer on a glass substrate (Cu/G). The XRD and the effectiveness of the electrocatalytic and catalytic properties of the Cu/G have been applied for an amperometric detection of glucose and for the chemical reduction of 4-nitrophenol. The former exhibited the detection limit as low as 2.47 μM with a linear range of 0.01–0.2 mM, while the latter showed the efficient catalytic activity with a high rate constant of 0.503/min. The current method suggested in this work might be useful for the fabrication of glass-based Cu nanoparticles electrodes for industrial and biomedical applications.
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- 2018
26. Recent Development in Nanomaterial-Based Electrochemical Sensors for Cholesterol Detection
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Hemraj M. Yadav, Jae-Joon Lee, Jongdeok Park, and Hyeong-Cheol Kang
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Materials science ,010401 analytical chemistry ,cholesterol ,Nanotechnology ,02 engineering and technology ,electrochemical ,QD415-436 ,021001 nanoscience & nanotechnology ,biosensor ,01 natural sciences ,Biochemistry ,0104 chemical sciences ,Analytical Chemistry ,Nanomaterials ,Clinical diagnosis ,Environmental stability ,lipids (amino acids, peptides, and proteins) ,Physical and Theoretical Chemistry ,0210 nano-technology ,Biosensor ,nanomaterials ,Healthcare system - Abstract
Functional nanomaterials have attracted significant attention in a variety of research fields (in particular, in the healthcare system) because of the easily controllable morphology, their high chemical and environmental stability, biocompatibility, and unique optoelectronic and sensing properties. The sensing properties of nanomaterials can be used to detect biomolecules such as cholesterol. Over the past few decades, remarkable progress has been made in the production of cholesterol biosensors that contain nanomaterials as the key component. In this article, various nanomaterials for the electrochemical sensing of cholesterol were reviewed. Cholesterol biosensors are recognized tools in the clinical diagnosis of cardiovascular diseases (CVDs). The function of nanomaterials in cholesterol biosensors were thoroughly discussed. In this study, different pathways for the sensing of cholesterol with functional nanomaterials were investigated.
- Published
- 2021
27. Sensitivity control of dopamine detection by conducting poly(thionine)
- Author
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Md. Mahbubur Rahman and Jae-Joon Lee
- Subjects
endocrine system ,Sensitivity control ,Dopamine ,02 engineering and technology ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,Thionine ,Catalysis ,chemistry.chemical_compound ,medicine ,Electrochemical detection ,Surface charge ,QD1-999 ,Poly(thionine) ,Conducting polymer ,Electropolymerization ,021001 nanoscience & nanotechnology ,Ascorbic acid ,0104 chemical sciences ,TP250-261 ,Chemistry ,chemistry ,Polymerization ,Industrial electrochemistry ,Uric acid ,0210 nano-technology ,hormones, hormone substitutes, and hormone antagonists ,Nuclear chemistry ,medicine.drug - Abstract
We investigated conducting poly(thionine) (PTH) films prepared by single-step and double-step electrochemical methods (PTH-S and PTH-D, respectively) on the surface of a glassy carbon electrode (GCE) for the detection of dopamine (DA) with varying sensitivity. Electrochemical and spectroscopic analysis revealed that both PTH films have identical chemical structures, but the sensitivity of DA detection was significantly dependent on the polymerization conditions. A simple variation of the electropolymerization conditions dramatically changed the catalytic activity of the PTH films towards the oxidation of DA in the presence of ascorbic acid (AA) and uric acid (UA) as well as the PTH formation mechanism. PTH-D was found to have a higher surface charge than PTH-S, and also showed a sensitivity enhancement for DA detection of up to one order of magnitude compared to PTH-S.
- Published
- 2021
28. The IGRINS YSO Survey I. Stellar parameters of pre-main sequence stars in Taurus-Auriga
- Author
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Christopher M. Johns-Krull, H. M. Lee, Michael Gully-Santiago, Benjamin Kidder, Larissa Nofi, Lisa Prato, Soojong Pak, Kyle F. Kaplan, Adam L. Kraus, Hwihyun Kim, Heeyoung Oh, Chan Park, Jae-Joon Lee, Andrew W. Mann, Daniel T. Jaffe, Gregory N. Mace, Joe Llama, Kimberly R. Sokal, Ricardo López-Valdivia, Jae Sok Oh, Maryam Hussaini, and Narae Hwang
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Physics ,AURIGA ,Young stellar object ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Effective temperature ,Surface gravity ,01 natural sciences ,Spectral line ,010309 optics ,Astrophysics - Solar and Stellar Astrophysics ,13. Climate action ,Space and Planetary Science ,0103 physical sciences ,TW Hydrae ,Continuum (set theory) ,010303 astronomy & astrophysics ,Main sequence ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
We present fundamental parameters for 110 canonical K- & M-type (1.3$-$0.13$M_\odot$) Taurus-Auriga young stellar objects (YSOs). The analysis produces a simultaneous determination of effective temperature ($T_{\rm eff}$), surface gravity ($\log$ g), magnetic field strength (B), and projected rotational velocity ($v \sin i$). Our method employed synthetic spectra and high-resolution (R$\sim$45,000) near-infrared spectra taken with the Immersion GRating INfrared Spectrometer (IGRINS) to fit specific K-band spectral regions most sensitive to those parameters. The use of these high-resolution spectra reduces the influence of distance uncertainties, reddening, and non-photospheric continuum emission on the parameter determinations. The median total (fit + systematic) uncertainties were 170 K, 0.28 dex, 0.60 kG, 2.5 km s$^{-1}$ for $T_{\rm eff}$, $\log$ g, B, and $v \sin i$, respectively. We determined B for 41 Taurus YSOs (upper limits for the remainder) and find systematic offsets (lower $T_{\rm eff}$, higher $\log$ g and $v \sin i$) in parameters when B is measurable but not considered in the fit. The average $\log$ g for the Class II and Class III objects differs by 0.23$\pm$0.05dex, which is consistent with Class III objects being the more evolved members of the star-forming region. However, the dispersion in $\log$ g is greater than the uncertainties, which highlights how the YSO classification correlates with age ($\log$ g), yet there are exceptionally young (lower $\log$ g) Class III YSOs and relatively old (higher $\log$ g) Class II YSOs with unexplained evolutionary histories. The spectra from this work are provided in an online repository along with TW Hydrae Association (TWA) comparison objects and the model grid used in our analysis., 21 pages, 10 figures, 5 tables. Accepted for publication in ApJ
- Published
- 2021
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29. Hybridisation of perovskite nanocrystals with organic molecules for highly efficient liquid scintillators
- Author
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Hyungsang Kim, Jungwon Kwak, Sangeun Cho, Sang Uck Lee, Eun Bi Nam, Jongmin Kim, SeungNam Cha, Sam Kyu Noh, Hyunsik Im, Yongcheol Jo, Ilhwan Ryu, Seongsu Hong, Sung-woo Kim, and Jae-Joon Lee
- Subjects
lcsh:Applied optics. Photonics ,Materials science ,Physics::Instrumentation and Detectors ,Quantum yield ,02 engineering and technology ,Scintillator ,010402 general chemistry ,01 natural sciences ,Article ,Particle detector ,X-rays ,lcsh:QC350-467 ,Perovskite (structure) ,Scintillation ,Quantum dots ,business.industry ,lcsh:TA1501-1820 ,Radioluminescence ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Nanocrystal ,Quantum dot ,Optoelectronics ,0210 nano-technology ,business ,lcsh:Optics. Light - Abstract
Compared with solid scintillators, liquid scintillators have limited capability in dosimetry and radiography due to their relatively low light yields. Here, we report a new generation of highly efficient and low-cost liquid scintillators constructed by surface hybridisation of colloidal metal halide perovskite CsPbA3 (A: Cl, Br, I) nanocrystals (NCs) with organic molecules (2,5-diphenyloxazole). The hybrid liquid scintillators, compared to state-of-the-art CsI and Gd2O2S, demonstrate markedly highly competitive radioluminescence quantum yields under X-ray irradiation typically employed in diagnosis and treatment. Experimental and theoretical analyses suggest that the enhanced quantum yield is associated with X-ray photon-induced charge transfer from the organic molecules to the NCs. High-resolution X-ray imaging is demonstrated using a hybrid CsPbBr3 NC-based liquid scintillator. The novel X-ray scintillation mechanism in our hybrid scintillators could be extended to enhance the quantum yield of various types of scintillators, enabling low-dose radiation detection in various fields, including fundamental science and imaging., Optics: Hybrid liquid scintillator with enhanced light output A hybrid liquid scintillator could be used in low-dose radiation detectors for use in imaging applications and scientific research. Highly sensitive X-ray detection is increasingly being used in industrial and military applications and for fundamental scientific research. Although liquid scintillators are more resilient to damage from exposure to intense radiation than crystalline or plastic scintillators, they have relatively low density and low radioluminescence quantum yields, both of which are critical for achieving high resolution and contrast in X-ray imaging. Now, a team of Korean researchers led by Hyunsik Im from Dongguk University has created a liquid scintillator detector made from colloidal perovskite metal halide nanocrystals and organic molecules with a significantly enhanced quantum yield. The novel device could see use in a wide range of X-ray technologies that require high-performance detectors and imagers.
- Published
- 2020
30. Fluorine in the solar neighbourhood: the need for several cosmic sources
- Author
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Verne V. Smith, Kyle F. Kaplan, Henrik Jönsson, Gregory N. Mace, B. Thorsbro, E. Spitoni, Rebecca Forsberg, Heeyoung Oh, Benjamin Kidder, Daniel T. Jaffe, E. Strickland, Nils Ryde, Kimberly R. Sokal, Christopher Sneden, Katia Cunha, Jae-Joon Lee, Melike Afşar, and Ege Üniversitesi
- Subjects
010504 meteorology & atmospheric sciences ,Infrared ,Metallicity ,FOS: Physical sciences ,chemistry.chemical_element ,Astrophysics ,01 natural sciences ,7. Clean energy ,Spectral line ,Abundance (ecology) ,0103 physical sciences ,010303 astronomy & astrophysics ,Stellar evolution ,Solar and Stellar Astrophysics (astro-ph.SR) ,0105 earth and related environmental sciences ,Physics ,COSMIC cancer database ,Astronomy and Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Stars ,chemistry ,Astrophysics - Solar and Stellar Astrophysics ,13. Climate action ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,Fluorine - Abstract
The cosmic origin of fluorine is still not well constrained. Several nucleosynthetic channels at different phases of stellar evolution have been suggested, but these must be constrained by observations. For this, the fluorine abundance trend with metallicity spanning a wide range is required. Our aim is to determine stellar abundances of fluorine for -1.1 < [Fe H] < +0.4. We determine the abundances from HF lines in infrared K-band spectra ( 2.3 mm) of cool giants, observed with the IGRINS and Phoenix high-resolution spectrographs. We derive accurate stellar parameters for all our observed K giants, which is important as the HF lines are very temperaturesensitive. We find that [F/Fe] is flat as a function of metallicity at [ F/Fe]0, but increases as the metallicity increases. the fluorine slope shows a clear secondary behavior in this metallicity range. We also find that the [F/ Ce] ratio is relatively flat for -0.6 < [Fe H] < 0, and that for two metal-poor ([Fe H] < - 0.8), s-process element-enhanced giants, we do not detect an elevated fluorine abundance. We interpret all of these observational constraints as indications that several major processes are at play for the cosmic budget of fluorine over time: from those in massive stars at low metallicities, through the asymptotic giant branch star contribution at -0.6 < [Fe H] < 0, to processes with increasing yields with metallicity at supersolar metallicities. the origins of the latter, and whether or not Wolf-Rayet stars and/or novae could contribute at supersolar metallicities, is currently not known. To quantify these observational results, theoretical modeling is required. More observations in the metal-poor region are required to clarify the processes there., Swedish Research Council, V.R.Swedish Research Council [621-2014-5640]; Royal Physiographic Society in Lund through the Stiftelse Walter Gyllenbergs fond; Crafoord Foundation; Stiftelsen Olle Engkvist ByggmastareSwedish Research Council; Ruth och Nils-Erik Stenbacks stiftelse; US National Science FoundationNational Science Foundation (NSF) [AST-1229522, AST-1702267]; McDonald Observatory of the University of Texas at Austin; Korean GMT Project of KASI, We would like to thank George Meynet for fruitful and enlightening discussions on massive-star yields and the theoretically predicted role of Wolf-Rayet stars for the production of fluorine. N.R. acknowledges support from the Swedish Research Council, V.R. (project numbers 621-2014-5640), and the Royal Physiographic Society in Lund through the Stiftelse Walter Gyllenbergs fond and Marta och Erik Holmbergs donation. H.J. acknowledges support from the Crafoord Foundation, Stiftelsen Olle Engkvist Byggmastare, and Ruth och Nils-Erik Stenbacks stiftelse. This work used the Immersion Grating Infrared spectrograph (IGRINS) that was developed under a collaboration between the University of Texas at Austin and the Korea Astronomy and Space Science Institute (KASI) with the financial support of the US National Science Foundation under grants AST-1229522 and AST-1702267, of the McDonald Observatory of the University of Texas at Austin, and of the Korean GMT Project of KASI. Facilities: McDonald Observatory (IGRINS), Lowell Observatory (IGRINS), KPNO (Phoenix).
- Published
- 2020
31. A non-absorbing organic redox couple for sensitization-based solar cells with metal-free polymer counter electrode
- Author
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Md. Mahbubur Rahman, Jae-Joon Lee, Narayan Chandra Deb Nath, and Jia Wang
- Subjects
chemistry.chemical_classification ,Auxiliary electrode ,Standard hydrogen electrode ,General Chemical Engineering ,Iodide ,02 engineering and technology ,Electrolyte ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,Redox ,0104 chemical sciences ,Dication ,chemistry.chemical_compound ,chemistry ,Electrode ,Electrochemistry ,0210 nano-technology ,Polysulfide - Abstract
An organo-sulfur compound, 5-methylthio-1,3,4-thiadiazole-2-thiol and its oxidized dimer 5-methylthio-1,3,4-thiadiazolium disulfide dication are used as a novel and universal redox couple in both dye-sensitized and quantum-dot sensitized solar cells, in conjunction with a conducting poly(3,4-ethylenedioxythiophene) counter electrode. The 5-methylthio-1,3,4-thiadiazole-2-thiol/5-methylthio-1,3,4-thiadiazolium disulfide dication redox couple is low-cost and easily processable, and exhibits non-absorption of visible light, showing improved redox behavior at an electrochemically deposited poly(3,4-ethylenedioxythiophene) counter electrode. Its redox potential is ca. 60 mV negatively and ca. 170 mV (vs. normal hydrogen electrode) positively positioned than those of iodide/tri-iodide and polysulfide electrolytes, respectively. The maximum power conversion efficiency of (3.55 and 1.20) % is obtained in dye and quantum-dot sensitized solar cells, respectively, sensitized by 5-[[4-[4-(2, 2-Diphenylethenyl) phenyl]-1,2,3,3a,4,8b hexahydrocyclopent [b] indol-7-yl] methylene]-2-(3-octyl-4-oxo-2-thioxo-5-thiazolid dye and CdS-quantum dot, respectively, together with the optimized poly(3,4-ethylenedioxythiophene) counter electrode. These results clearly outperform the performance of identical dye and quantum-dot sensitized solar cells with Pt and Cu2S-counter electrodes. Thus, this new redox couple and poly(3,4-ethylenedioxythiophene) counter electrode pair is expected to offer a promising and universal alternative to the conventional iodide/tri-iodide and polysulfide electrolytes for sensitization-based solar cells.
- Published
- 2018
32. Influence of anti-solvents on CH3NH3PbI3 films surface morphology for fabricating efficient and stable inverted planar perovskite solar cells
- Author
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Towhid H. Chowdhury, Md. Emrul Kayesh, Kiyoto Matsuishi, Takeshi Noda, Ryuji Kaneko, Jae-Joon Lee, and Ashraful Islam
- Subjects
Fabrication ,Materials science ,Morphology (linguistics) ,Photovoltaic system ,Energy conversion efficiency ,Metals and Alloys ,Ether ,02 engineering and technology ,Surfaces and Interfaces ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Toluene ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Chlorobenzene ,Materials Chemistry ,0210 nano-technology ,Perovskite (structure) - Abstract
The stability of perovskite solar cells (PSCs) are critically related to the perovskite crystal morphology and film quality, hence controlling the perovskite film formation is one of the key concerns. In this study, we have used four anti-solvents- toluene, chlorobenzene, p-xylene and ether to fabricate high quality CH3NH3PbI3 perovskite films. We investigated the surface morphology, optical and structural properties of the corresponding perovskite films. Consequently, PSCs with variation of these anti-solvents were fabricated and the respective photovoltaic performances over a period of 30 days in dark and under air mass 1.5G sunlight conditions have been observed. Our analyses onto the post fabrication of PSCs highlight that, the perovskite films formed by toluene, chlorobenzene and p-xylene treatment results in high efficient and stable PSCs in dark. Interestingly, the ether treated PSC had no photovoltaic response after 10 days. The toluene and chlorobenzene treated PSCs showed stable device performance and retained 90% of their initial power conversion efficiency even after 30 days light soaking. The p-xylene treated PSCs showed unstable performance during the same light soaking period.
- Published
- 2018
33. Low temperature processed inverted planar perovskite solar cells by r-GO/CuSCN hole-transport bilayer with improved stability
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Md. Emrul Kayesh, Takeshi Noda, Towhid H. Chowdhury, Ryuji Kaneko, Ashraful Islam, Jae-Joon Lee, and Md. Akhtaruzzaman
- Subjects
Materials science ,Renewable Energy, Sustainability and the Environment ,Graphene ,Open-circuit voltage ,business.industry ,Bilayer ,Energy conversion efficiency ,Oxide ,Perovskite solar cell ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,Copper(I) thiocyanate ,chemistry ,law ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business ,Perovskite (structure) - Abstract
Low temperature processed Perovskite solar cells (PSCs) are popular due to their potential for scalable production. In this work, we report reduced Graphene Oxide (r-GO)/copper (I) thiocyanate (CuSCN) as an efficient bilayer hole transport layer (HTL) for low temperature processed inverted planar PSCs. We have systematically optimized the thickness of CuSCN interlayer at the r-GO/MAPbI3 interface resulting in bilayer HTL structure to enhance the stability and photovoltaic performance of low temperature processed r-GO HTL based PSCs with a standard surface area of 1.02 cm2. With matched valence band energy level, the r-GO/CuSCN bilayer HTL based PSCs showed high power conversion efficiency of 14.28%, thanks to the improved open circuit voltage (VOC) compared to the only r-GO based PSC. Moreover, enhanced stability has been observed for the r-GO/CuSCN based PSCs which retained over 90% of its initial efficiency after 100 h light soaking measured under continuous AM 1.5 sun illumination.
- Published
- 2018
34. Large-Scale Production of APbX3 Perovskites in Powder Form with High Stability
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Gavindasamy Murugadoss, Jae-Joon Lee, and Narayan Chandra Deb Nath
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Materials science ,Scale (ratio) ,business.industry ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Stability (probability) ,0104 chemical sciences ,Production (economics) ,General Materials Science ,0210 nano-technology ,Process engineering ,business - Published
- 2018
35. Enhanced Photovoltaic Performance of FASnI3-Based Perovskite Solar Cells with Hydrazinium Chloride Coadditive
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Towhid H. Chowdhury, Md. Emrul Kayesh, Jae-Joon Lee, Kiyoto Matsuishi, Ryuji Kaneko, Ashraful Islam, Said Kazaoui, and Takeshi Noda
- Subjects
Solvent system ,Fabrication ,Materials science ,Renewable Energy, Sustainability and the Environment ,Photovoltaic system ,Energy conversion efficiency ,Energy Engineering and Power Technology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Chloride ,0104 chemical sciences ,Fuel Technology ,Chemical engineering ,Chemistry (miscellaneous) ,Reduced concentration ,Materials Chemistry ,medicine ,0210 nano-technology ,medicine.drug - Abstract
For the fabrication of efficient Sn-based perovskite solar cells (PSCs), deposition of uniform and pinhole-free perovskite films with low Sn4+ content remains a crucial factor. In this work, we present a coadditive engineering process by introduction of hydrazinium chloride (N2H5Cl) in a single precursor solvent system to fabricate FASnI3 perovskite films. The successful integration of N2H5Cl results in reduced concentration of Sn4+ content by 20% in the FASnI3 film leading to suppressed carrier recombination and pinhole-free uniform coverage. These remarkable improvements in the FASnI3 film results in power conversion efficiency (PCE) of Sn-based PSC up to 5.4% due to a significant increase in open-circuit voltage. Moreover, the best PSC without encapsulation showed stable shelf life up to 1000 h while retaining 65% of its initial PCE.
- Published
- 2018
36. Full waveform inversion using a decomposed single frequency component from a spectrogram
- Author
-
Jiho Ha, Wookeen Chung, Young-Ju Kim, Nam-Hyung Koo, Sang-Mok Han, Jae-Joon Lee, Sungryul Shin, Changsoo Shin, Nam-Sub Woo, and Seongpil Kim
- Subjects
Hessian matrix ,010504 meteorology & atmospheric sciences ,Frequency band ,Diagonal ,Wavelet transform ,Inversion (meteorology) ,010502 geochemistry & geophysics ,01 natural sciences ,Matrix decomposition ,symbols.namesake ,Geophysics ,symbols ,Spectrogram ,Algorithm ,0105 earth and related environmental sciences ,Salt dome ,Mathematics - Abstract
Although many full waveform inversion methods have been developed to construct velocity models of subsurface, various approaches have been presented to obtain an inversion result with long-wavelength features even though seismic data lacking low-frequency components were used. In this study, a new full waveform inversion algorithm was proposed to recover a long-wavelength velocity model that reflects the inherent characteristics of each frequency component of seismic data using a single-frequency component decomposed from the spectrogram. We utilized the wavelet transform method to obtain the spectrogram, and the decomposed signal from the spectrogram was used as transformed data. The Gauss–Newton method with the diagonal elements of an approximate Hessian matrix was used to update the model parameters at each iteration. Based on the results of time–frequency analysis in the spectrogram, numerical tests with some decomposed frequency components were performed using a modified SEG/EAGE salt dome (A–A′) line to demonstrate the feasibility of the proposed inversion algorithm. This demonstrated that a reasonable inverted velocity model with long-wavelength structures can be obtained using a single frequency component. It was also confirmed that when strong noise occurs in part of the frequency band, it is feasible to obtain a long-wavelength velocity model from the noise data with a frequency component that is less affected by the noise. Finally, it was confirmed that the results obtained from the spectrogram inversion can be used as an initial velocity model in conventional inversion methods.
- Published
- 2018
37. Electrodeposition of Cu2S nanoparticles on fluorine-doped tin oxide for efficient counter electrode of quantum-dot-sensitized solar cells
- Author
-
Md. Mahbubur Rahman, Chuangye Ge, Jia Wang, and Jae-Joon Lee
- Subjects
Auxiliary electrode ,Materials science ,General Chemical Engineering ,Energy conversion efficiency ,Nanoparticle ,02 engineering and technology ,Electrolyte ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,Tin oxide ,01 natural sciences ,0104 chemical sciences ,Chemical engineering ,Quantum dot ,Electrode ,0210 nano-technology - Abstract
This study demonstrated a single-step potentiostatic method for the electrodeposition of copper (I) sulfide (Cu2S) nanoparticles onto fluorine-doped tin oxide (FTO) electrode from an aqueous solution of CuCl2 and thiourea (TU) to develop counter electrodes (CEs) for quantum-dot sensitized solar cells (QDSSCs). The homogeneously distributed and optimized Cu2S–CE exhibited an improved catalytic activity in the reduction of polysulfide (S2−/Sn2−) electrolyte, which resulted in a power conversion efficiency (PCE) of 4.24% with a short-circuit current density (Jsc), open-circuit voltage (Voc), and fill factor (FF) of 19.60 mA/cm2, 0.445 V, and 48.62%, respectively, for PbS/CdS/ZnS QDs sensitized QDSSCs, while the Pt counterpart exhibited a PCE of 1.17%. The superior photovoltaic performance of this Cu2S–CEs based QDSSC compared to the Pt counterpart is due to its greater electrocatalytic activity and lower charge transfer resistance (RCT) at the Cu2S–CEs/(S2−/Sn2−) interface. This strategy provides an effective, low-cost, and non-Pt electrode for QDSSCs, which is promising for other electrochemical applications.
- Published
- 2018
38. Nanostructured copper–cobalt based spinel for the electrocatalytic H2O2 reduction reaction
- Author
-
Eun-Kyung Kim, Narayan Chandra Deb Nath, Trishna Debnath, AA Shaikh, and Jae-Joon Lee
- Subjects
Materials science ,General Chemical Engineering ,Spinel ,Limiting current ,Nanoparticle ,chemistry.chemical_element ,02 engineering and technology ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrocatalyst ,01 natural sciences ,Redox ,Copper ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Electrochemistry ,engineering ,0210 nano-technology ,Hydrogen peroxide ,Cobalt - Abstract
Nanostructured copper–cobalt based spinel [(Cu0.30Co0.70)Co2O4] was employed as an electrocatalyst in the hydrogen peroxide (H2O2) reduction reaction (HRR). Both nanoparticles and nanoneedles co-existed in the (Cu0.30Co0.70)Co2O4 spinel, which exhibited a high intrinsic electrical conductivity and surface-to-volume ratio, resulting therefore in a large electrochemically active surface area for the HRR. In addition, (Cu0.30Co0.70)Co2O4 showed an onset potential at approximately −0.14 V in the HRR, with a limiting current density of ∼104 mA/cm2 at −0.43 V. The synthesised material followed the direct HRR pathway and exhibited good stability. In addition, the HRR activity of (Cu0.30Co0.70)Co2O4 was comparable to that of commercial Pt/C electrodes. The present results therefore demonstrate the significant potential of (Cu0.30Co0.70)Co2O4 for future applications in fuel cells as a cathode catalyst.
- Published
- 2018
39. Application of ionic liquids for metal dissolution and extraction
- Author
-
Yeji Kang, Jae-Joon Lee, Eui Joo Lee, and Byung-Kwon Kim
- Subjects
Metal dissolution ,Materials science ,General Chemical Engineering ,Metal ions in aqueous solution ,Extraction (chemistry) ,Inorganic chemistry ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Metal ,Pickling Agents ,chemistry.chemical_compound ,chemistry ,visual_art ,Ionic liquid ,visual_art.visual_art_medium ,0210 nano-technology ,Dissolution - Abstract
This review summarizes the results of studies on the selective dissolution and extraction of Fe, Cr, Cu, and Zn by ionic liquids, as an alternative to the use of conventional molten salts or pickling agents, for various types of steel. Ionic liquids are classified according to the metals, metal ions, and metal oxides by which they can be extracted or dissolved. The results of the metal extraction efficiency per unit time presented in the literature are summarized in a simple unified graphic format. This provides a comparative understanding of the most efficient ionic liquid for the extraction of specific metals.
- Published
- 2018
40. Kinematic evidence for feedback-driven star formation in NGC 1893
- Author
-
Hyeonoh Hur, Beomdu Lim, Michael S. Bessell, Sang-Woo Lee, Narae Hwang, Kyeongsoo Hong, Heeyoung Oh, Hwankyung Sung, Byeong-Gon Park, Sunkyung Park, and Jae-Joon Lee
- Subjects
Physics ,010308 nuclear & particles physics ,Star formation ,Astrophysics::High Energy Astrophysical Phenomena ,Foundation (engineering) ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Kinematics ,Astrophysics - Astrophysics of Galaxies ,01 natural sciences ,Engineering management ,Astrophysics - Solar and Stellar Astrophysics ,Work (electrical) ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
OB associations are the prevailing star forming sites in the Galaxy. Up to now, the process of how OB associations were formed remained a mystery. A possible process is self-regulating star formation driven by feedback from massive stars. However, although a number of observational studies uncovered various signposts of feedback-driven star formation, the effectiveness of such feedback has been questioned. Stellar and gas kinematics is a promising tool to capture the relative motion of newborn stars and gas away from ionizing sources. We present high-resolution spectroscopy of stars and gas in the young open cluster NGC 1893. Our findings show that newborn stars and the tadpole nebula Sim 130 are moving away from the central cluster containing two O-type stars, and that the timescale of sequential star formation is about 1 Myr within a 9 parsec distance. The newborn stars formed by feedback from massive stars account for at least 18 per cent of the total stellar population in the cluster, suggesting that this process can play an important role in the formation of OB associations. These results support the self-regulating star formation model., Comment: 13 pages, 7 figures, 3 tables, accepted for publication in MNRAS
- Published
- 2018
41. Panchromatic absorption of dye sensitized solar cells by co-Sensitization of triple organic dyes
- Author
-
Chuanjiang Qin, Towhid H. Chowdhury, Nicolas Leclerc, Liyuan Han, Antoine Mirloup, Kamaruzzaman Sopian, Idriss Bedja, Akhtaruzzaman, Jae-Joon Lee, Ashraful Islam, National Institute for Materials Science (NIMS), Kyushu University [Fukuoka], Institut de chimie et procédés pour l'énergie, l'environnement et la santé (ICPEES), Université de Strasbourg (UNISTRA)-Matériaux et nanosciences d'Alsace (FMNGE), and Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Renewable Energy, Sustainability and the Environment ,Energy Engineering and Power Technology ,Co sensitization ,chemistry.chemical_element ,[CHIM.MATE]Chemical Sciences/Material chemistry ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,7. Clean energy ,01 natural sciences ,0104 chemical sciences ,Dye-sensitized solar cell ,chemistry.chemical_compound ,Fuel Technology ,chemistry ,Molar ratio ,[CHIM]Chemical Sciences ,BODIPY ,0210 nano-technology ,Spectroscopy ,Boron ,Absorption (electromagnetic radiation) ,ComputingMilieux_MISCELLANEOUS - Abstract
Dye sensitized solar cells (DSSCs) were co-sensitized with three custom molecularly engineered organic dyes containing butyloxyl chain induced dye (Y1), boron dipyrromethene (bodipy) dye (TP2A), and squaraine (SQ) ring configured dye (HSQ4). The individual power conversion efficiencies of the DSSCs sensitized with Y1, TP2A and HSQ4 sensitizers were 3.44%, 4.26% and 5.78%, respectively. Co-sensitized TP2A + HSQ4 dyes at a 2 : 1 molar ratio showed an efficiency of 7.02%. Further addition of Y1 dye with optimal TP2A + HSQ4 increased the VOC from 0.580 V to 0.605 V. The co-sensitized Y1 + TP2A + HSQ4 based DSSCs showed a new optimal efficiency (η) of 7.48%. This is the highest efficiency recorded for DSSCs based on co-sensitization of triple organic dyes. Intensity modulated photovoltage spectroscopy further confirms the longer lifetime of co-sensitized Y1 + TP2A + HSQ4 compared to that of each individual TP2A and HSQ4 and co-sensitized TP2A + HSQ4 dye.
- Published
- 2018
42. A Conducting Poly(N-(1-Naphthyl)ethylenediamine dihydrochloride) Nanofibers for the Sensitive and Interference-Free Detection of Dopamine
- Author
-
Jae-Joon Lee, Arif Ahmed, and Md. Mahbubur Rahman
- Subjects
Renewable Energy, Sustainability and the Environment ,Chemistry ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Interference (communication) ,Dopamine ,Nanofiber ,Materials Chemistry ,Electrochemistry ,medicine ,0210 nano-technology ,medicine.drug ,Nuclear chemistry ,N-(1-Naphthyl)ethylenediamine - Published
- 2018
43. Protective Effects of Loquat (Eriobotrya japonica Lindl.) Leaf Extract on Ethanol-Induced Liver Damage in Rats
- Author
-
Hwan Lee, Yeon Jin Park, and Jae-Joon Lee
- Subjects
0106 biological sciences ,0301 basic medicine ,Loquat Leaf ,030109 nutrition & dietetics ,Ethanol ,biology ,Eriobotrya ,biology.organism_classification ,01 natural sciences ,Japonica ,03 medical and health sciences ,chemistry.chemical_compound ,Horticulture ,chemistry ,010608 biotechnology ,Liver damage - Published
- 2017
44. Modulation of energy levels and vertical charge transport in polythiophene through copolymerization of non-fluorinated and fluorinated units for organic indoor photovoltaics
- Author
-
Benjamin Nketia-Yawson, Hyungju Ahn, Ranbir Singh, Jea Woong Jo, Min Jae Ko, Seong Yeon Ko, and Jae-Joon Lee
- Subjects
chemistry.chemical_classification ,education.field_of_study ,Materials science ,business.industry ,Process Chemistry and Technology ,General Chemical Engineering ,Population ,02 engineering and technology ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Photovoltaics ,Copolymer ,Polythiophene ,Optoelectronics ,Crystallite ,0210 nano-technology ,education ,business ,Diode ,Voltage - Abstract
Organic indoor photovoltaics (OIPVs) for the development of a wireless power supplier that allows the portable operation of Internet-of-things and low-energy consumption devices have received tremendous interest. Particularly, polythiophene represented by poly(3-hexylthiophene) has been considered as a promising photoactive material for OIPVs owing to their desirable optoelectrical properties and power conversion efficiencies (PCEs) that exceed Si-based PVs under low-intensity illumination. However, the polythiophene-based OIPVs suffer from an inadequate charge transporting ability in the out-of-plane direction and a low open-circuit voltage (VOC), which currently hinder the further improvement of OIPVs. Herein, we designed and synthesized a new polythiophene derivative by combining fluorination and random copolymerization strategies. The optimized polymer obtained by tuning the ratio of fluorinated and non-fluorinated bi-thiophene units showed an increased population of face-on oriented crystallites, a denser packing, and a deeper highest occupied molecule orbital energy level compared with its homopolymer analogue. The optimized polymer was also revealed to provide improved vertical charge transport than homopolymer analogue. As a result, when fabricated using the phenyl-C71-butyric acid methyl ester as an electron-acceptor, the OIPVs with the optimized polymer showed high PCEs up to 13.4% with VOC of 0.68 V under 1000 lux white light-emitting diode illumination, which were improved values compared with the efficiencies observed in the devices with homopolymer (PCE = 5.6% and VOC = 0.57 V).
- Published
- 2021
45. IGRINS RV: A Precision Radial Velocity Pipeline for IGRINS Using Modified Forward Modeling in the Near-infrared*
- Author
-
Lisa Prato, Jae-Joon Lee, Jessica Luna, Daniel T. Jaffe, Heeyoung Oh, Christopher M. Johns-Krull, Joe Llama, Shih-Yun Tang, Gregory N. Mace, and Asa G. Stahl
- Subjects
Physics ,business.industry ,Pipeline (computing) ,Starspot ,Near-infrared spectroscopy ,Astronomy and Astrophysics ,Open source software ,01 natural sciences ,010309 optics ,Radial velocity ,Optics ,Space and Planetary Science ,0103 physical sciences ,business ,010303 astronomy & astrophysics - Published
- 2021
46. A Study on Selection of Block Stockyard Applying Decision Tree Learning Algorithm
- Author
-
Jae-Joon Lee, Byeong-Wook Nam, Seung-Hwan Mun, and Kyungho Lee
- Subjects
Incremental decision tree ,Computer science ,business.industry ,Decision tree learning ,ID3 algorithm ,020101 civil engineering ,02 engineering and technology ,Machine learning ,computer.software_genre ,01 natural sciences ,010305 fluids & plasmas ,0201 civil engineering ,0103 physical sciences ,Artificial intelligence ,business ,computer ,Selection (genetic algorithm) ,Block (data storage) - Published
- 2017
47. An arbitrary-order staggered time integrator for the linear acoustic wave equation
- Author
-
Changsoo Shin, Yoonseo Park, Hyun-Seo Park, and Jae-Joon Lee
- Subjects
Physics ,010504 meteorology & atmospheric sciences ,Wave propagation ,Acoustics ,Mathematical analysis ,Order (ring theory) ,010502 geochemistry & geophysics ,Exponential integrator ,01 natural sciences ,Geophysics ,Geochemistry and Petrology ,Integrator ,Acoustic wave equation ,0105 earth and related environmental sciences ,Computational seismology - Published
- 2017
48. Highly sensitive and simultaneous detection of dopamine and uric acid at graphene nanoplatelet-modified fluorine-doped tin oxide electrode in the presence of ascorbic acid
- Author
-
Md. Mahbubur Rahman, Myung Jong Ju, Nasrin Siraj Lopa, and Jae-Joon Lee
- Subjects
Detection limit ,Graphene ,General Chemical Engineering ,Inorganic chemistry ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,Tin oxide ,Ascorbic acid ,01 natural sciences ,Oxygen ,0104 chemical sciences ,Analytical Chemistry ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,Electrode ,Uric acid ,0210 nano-technology - Abstract
We developed a graphene nanoplatelet-modified fluorine-doped tin oxide electrode (GNP/FTO) for the simultaneous detection of dopamine (DA) and uric acid (UA) in the presence of ascorbic acid (AA) and investigated the interaction mechanisms of DA, UA, and AA with GNPs considering their charging states at different pH values. Owing to the unique structure and properties originating from the oxygen and nitrogen functional groups at the edges, GNPs showed high electrocatalytic activity for the electrochemical oxidations of AA, DA, and UA with peak-to-peak potential separations (ΔEP) between AA-DA and DA-UA of ca. 0.23 and 0.17 V, respectively. These values are sufficiently high to allow the simultaneous detection of DA and UA without interference from AA. The highly sensitive and stable GNP/FTO sensor showed sensitivities of ca. 0.15 ± 0.004 and 0.14 ± 0.007 μA/μM, respectively, with detection limits of ca. 0.22 ± 0.009 and 0.28 ± 0.009 μM, respectively, for DA and UA. The sensor could detect DA and UA concentrations in human serum samples with excellent recoveries.
- Published
- 2017
49. Infrared diffuse interstellar bands
- Author
-
Byeong-Cheol Lee, G. Galazutdinov, G. Valyavin, Inwoo Han, Jacek Krełowski, and Jae-Joon Lee
- Subjects
Physics ,010504 meteorology & atmospheric sciences ,Diffuse interstellar band ,Space and Planetary Science ,Infrared ,0103 physical sciences ,Astronomy and Astrophysics ,Astrophysics ,010303 astronomy & astrophysics ,01 natural sciences ,0105 earth and related environmental sciences - Published
- 2017
50. Formation of uniform PbS quantum dots by a spin-assisted successive precipitation and anion exchange reaction process using PbX2 (X = Br, I) and Na2S precursors
- Author
-
Jin Hyuck Heo, Min Hyeok Jang, Myoung Sang You, Sang Hyuk Im, Sang-Wook Kim, Jae-Joon Lee, and Min-Ho Lee
- Subjects
Passivation ,Ion exchange ,Precipitation (chemistry) ,Chemistry ,General Chemical Engineering ,Ionic bonding ,Nanotechnology ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Adsorption ,Chemical engineering ,Quantum dot ,Halogen ,0210 nano-technology ,Mesoporous material - Abstract
We devised a straightforward spin-assisted successive precipitation and anion exchange reaction (spin-SPAER) process in order to deposit relatively uniform PbS quantum dots (QDs) on mesoporous TiO2 (mp-TiO2). For the spin-SPAER process, we used PbX2 (X = I, Br, and Cl) precursors instead of a Pb(NO3)2 precursor and consequently deposited individual PbS QDs on mp-TiO2 due to the suppressed overgrowth of PbS QDs, whereas the conventional spin-assisted successive ionic layer adsorption and reaction (spin-SILAR) process formed aggregated PbS QDs on the mp-TiO2 surface due to continuous adsorption and reaction. In addition, the PbS QDs prepared by spin-SPAER showed better air stability than the PbS QDs prepared by spin-SILAR possibly due to the passivation by halogen elements such as I and Br. Accordingly, we could improve the overall power conversion efficiency of PbS QD-SSCs prepared by the spin-SPAER process using PbI2 and PbBr2 precursors to ∼26.7% and ∼44.2%, respectively, compared to the PbS QD-SSCs prepared by spin-SILAR using the Pb(NO3)2 precursor.
- Published
- 2017
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