Search

Your search keyword '"Ahn, Tae Kyu"' showing total 382 results
Start Over Author "Ahn, Tae Kyu"
382 results on '"Ahn, Tae Kyu"'

3. Regulation of photosystem I light harvesting by zeaxanthin

Author

Ballottari, Matteo, Alcocer, Marcelo JP, D’Andrea, Cosimo, Viola, Daniele, Ahn, Tae Kyu, Petrozza, Annamaria, Polli, Dario, Fleming, Graham R, Cerullo, Giulio, and Bassi, Roberto

Subjects
Affordable and Clean Energy, Arabidopsis, Chlorophyll, Fluorescence, Kinetics, Light, Light-Harvesting Protein Complexes, Luminescent Measurements, Mutation, Photosynthesis, Photosystem I Protein Complex, Plant Leaves, Protein Binding, Time Factors, Xanthophylls, Zeaxanthins, photosynthesis, xanthophylls, violaxanthin de-epoxidase, photobleaching
Abstract

In oxygenic photosynthetic eukaryotes, the hydroxylated carotenoid zeaxanthin is produced from preexisting violaxanthin upon exposure to excess light conditions. Zeaxanthin binding to components of the photosystem II (PSII) antenna system has been investigated thoroughly and shown to help in the dissipation of excess chlorophyll-excited states and scavenging of oxygen radicals. However, the functional consequences of the accumulation of the light-harvesting complex I (LHCI) proteins in the photosystem I (PSI) antenna have remained unclarified so far. In this work we investigated the effect of zeaxanthin binding on photoprotection of PSI-LHCI by comparing preparations isolated from wild-type Arabidopsis thaliana (i.e., with violaxanthin) and those isolated from the A. thaliana nonphotochemical quenching 2 mutant, in which violaxanthin is replaced by zeaxanthin. Time-resolved fluorescence measurements showed that zeaxanthin binding leads to a previously unrecognized quenching effect on PSI-LHCI fluorescence. The efficiency of energy transfer from the LHCI moiety of the complex to the PSI reaction center was down-regulated, and an enhanced PSI resistance to photoinhibition was observed both in vitro and in vivo. Thus, zeaxanthin was shown to be effective in inducing dissipative states in PSI, similar to its well-known effect on PSII. We propose that, upon acclimation to high light, PSI-LHCI changes its light-harvesting efficiency by a zeaxanthin-dependent quenching of the absorbed excitation energy, whereas in PSII the stoichiometry of LHC antenna proteins per reaction center is reduced directly.

Published
2014

6. ARCHITECTURE OF A CHARGE-TRANSFER STATE REGULATING LIGHT HARVESTING IN A PLANT ANTENNA PROTEIN

Author

Ahn, Tae Kyu

Subjects
Inorganic, organic, physical and analytical chemistry, charge-transfer, light harvesting, plant antenna proteins, regulation of photosynthetic light harvesting, minor antenna complex CP29, coupled chlorophyll dimer
Abstract

Energy-dependent quenching of excess absorbed light energy (qE) is a vital mechanism for regulating photosynthetic light harvesting in higher plants. All of the physiological characteristics of qE have been positively correlated with charge-transfer between coupled chlorophyll and zeaxanthin molecules in the light-harvesting antenna of photosystem II (PSII). In this work, we present evidence for charge-transfer quenching in all three of the individual minor antenna complexes of PSII (CP29, CP26, and CP24), and we conclude that charge-transfer quenching in CP29 involves a de-localized state of an excitonically coupled chlorophyll dimer. We propose that reversible conformational changes in CP29 can `tune? the electronic coupling between the chlorophylls in this dimer, thereby modulating the energy of the chlorophylls-zeaxanthin charge-transfer state and switching on and off the charge-transfer quenching during qE.

Published
2008

10. Enhanced photocatalytic hydrogen production of microporous organic polymers by incorporation of afterglow phosphorescent materials.

Author

Ryu, Sang Hyun, Kim, Gye Hong, Ahn, Tae Kyu, Ko, Kyoung Chul, and Son, Seung Uk

Abstract

This work shows that photocatalytic hydrogen evolution from water by microporous organic polymer (MOP)-based photocatalysts can be enhanced by the incorporation of afterglow phosphorescent materials (AG). The photocatalytic MOPs were introduced on the surface of AG through the Stille coupling of tris(4-trimethylstannylphenyl)amine with 3,7-dibromodibenzothiophene sulfone. The resultant AG–MOP–TADS–Pds showed enhanced photocatalytic activities by 2.4 times, compared with MOP–TADS–Pd, due to the Förster resonance energy transfer or charge transfer between AG and MOP–TADS–Pds. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

17. Defect Healing in FAPb(I 1‐xBrx) 3 Perovskites: Multifunctional Fluorinated Sulfonate Surfactant Anchoring Enables >21% Modules with Improved Operation Stability (Adv. Energy Mater. 20/2022)

Author

Zhu, Jun, primary, Qian, Yongteng, additional, Li, Zijia, additional, Gong, Oh Yeong, additional, An, Zongfu, additional, Liu, Qing, additional, Choi, Jin Hyuk, additional, Guo, He, additional, Yoo, Pil Jin, additional, Kim, Dong Hoe, additional, Ahn, Tae Kyu, additional, Han, Gill Sang, additional, and Jung, Hyun Suk, additional

Published
2022
Full Text
View/download PDF

18. Defect Healing in FAPb(I1‐xBrx)3 Perovskites: Multifunctional Fluorinated Sulfonate Surfactant Anchoring Enables >21% Modules with Improved Operation Stability

Author

Zhu, Jun, primary, Qian, Yongteng, additional, Li, Zijia, additional, Gong, Oh Yeong, additional, An, Zongfu, additional, Liu, Qing, additional, Choi, Jin Hyuk, additional, Guo, He, additional, Yoo, Pil Jin, additional, Kim, Dong Hoe, additional, Ahn, Tae Kyu, additional, Han, Gill Sang, additional, and Jung, Hyun Suk, additional

Published
2022
Full Text
View/download PDF

35. Defect Healing in FAPb(I1‐xBrx)3 Perovskites: Multifunctional Fluorinated Sulfonate Surfactant Anchoring Enables >21% Modules with Improved Operation Stability.

Author

Zhu, Jun, Qian, Yongteng, Li, Zijia, Gong, Oh Yeong, An, Zongfu, Liu, Qing, Choi, Jin Hyuk, Guo, He, Yoo, Pil Jin, Kim, Dong Hoe, Ahn, Tae Kyu, Han, Gill Sang, and Jung, Hyun Suk

Subjects
METHYLAMMONIUM, PEROVSKITE, FLUOROSURFACTANTS, CHARGE carrier lifetime, SOLAR cells, SULFONIC acids
Abstract

Formamidinium lead triiodide‐based perovskite solar cells have emerged as one of the most promising candidates that can be potentially used to develop photovoltaic technologies in the future. The commercial use of perovskite solar cell modules (PSCMs) is limited as it is challenging to fabricate high‐quality, efficient, and stable large‐area perovskite light‐absorbing films. Heptadecafluorooctanesulfonic acid tetraethylammonium salt (HFSTT), containing fluorinated long alkyl chains as hydrophobic tails and sulfonic acid groups (SO3−) as hydrophilic heads, which exhibit a great synergistic potential in large‐area film uniform fabrication, crystallization orientation modulation, defect passivation, and device operation stability enhancement, are introduced. The HFSTT‐modified films exhibit a prominent (100) orientation and lower trap‐state density as well as enhanced carrier mobilities and diffusion lengths, facilitating a champion unit device with an impressive power conversion efficiency (PCE) of 23.88% (0.14 cm2) and 22.52% (1 cm2) with a low voltage deficit around 0.341 V. The unencapsulated device retains ≈70% of its initial efficiency after 1000 h under heat damping test (60 °C and ≈60% RH). Moreover, the PSCMs exhibiting PCEs of 21.05% (with notable fill factor 0.79) and 18.27% are characterized by the active areas of 25.98 and 60.68 cm2, respectively. [ABSTRACT FROM AUTHOR]

Published
2022
Full Text
View/download PDF

37. Formamidine disulfide oxidant as a localised electron scavenger for >20% perovskite solar cell modules

Author

Zhu, Jun, primary, Park, Seulyoung, additional, Gong, Oh Yeong, additional, Sohn, ChangHwun, additional, Li, Zijia, additional, Zhang, Zhenru, additional, Jo, Bonghyun, additional, Kim, Wooyul, additional, Han, Gill Sang, additional, Kim, Dong Hoe, additional, Ahn, Tae Kyu, additional, Lee, Jaichan, additional, and Jung, Hyun Suk, additional

Published
2021
Full Text
View/download PDF

38. Perovskite Photovoltaic Cells: Synergistic Effect of Excited State Property and Aggregation Characteristic of Organic Semiconductor on Efficient Hole‐Transportation in Perovskite Device (Adv. Funct. Mater. 5/2021)

Author

Jo, Bonghyun, primary, Park, Hansol, additional, Kamaraj, Eswaran, additional, Lee, Sewook, additional, Jung, Bumho, additional, Somasundaram, Sivaraman, additional, Jeon, Gyeong G., additional, Lee, Kyu‐Tae, additional, Kim, Namdoo, additional, Kim, Jong H., additional, Kim, Bong‐Gi, additional, Ahn, Tae Kyu, additional, Park, Sanghyuk, additional, and Park, Hui Joon, additional

Published
2021
Full Text
View/download PDF

40. Evidence for wavelike energy transfer through quantum coherence in photosynthetic systems

Author

Engel, Gregory S., Calhoun, Tessa R., Read, Elizabeth L., Ahn, Tae-Kyu, Mančal, Tomaš, Cheng, Yuan-Chung, Blankenship, Robert E., and Fleming, Graham R.

Subjects
Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Author(s): Gregory S. Engel [1, 2]; Tessa R. Calhoun [1, 2]; Elizabeth L. Read [1, 2]; Tae-Kyu Ahn [1, 2]; Tomáš Mančal [1, 2, 5]; Yuan-Chung Cheng [1, 2]; Robert [...]

Published
2007
Full Text
View/download PDF

41. Comparative photophysics of [26]- and [28]hexaphyrins(1.1.1.1.1.1): Large two-photon absorption cross section of aromatic [26]hexaphyrins(1.1.1.1.1.1)

Author

Ahn, Tae Kyu, Jung Ho Kwon, Deok Yun Kim, Dae Won Cho, Dae Hong Jeong, Seong Keun Kim, Suzuki, Masaaki, Shimizu, Soji, Osuka, Atsuhiro, and Dongho Kim

Subjects
Porphyrins -- Structure, Porphyrins -- Chemical properties, Absorption -- Analysis, Oxidation-reduction reaction -- Analysis, Chemistry
Abstract

The eletronic natures of representative expanded porphyrins, [26]- and [28]hexaphrins is explored to investigate the interplay between the aromaticity and antiaromaticity that is brought by two electron oxidation/reduction processes. The enhanced excited-state lifetimes for various hexaphyrins go in line with the increased two-photon absorption cross-section values and the ring planarity.

Published
2005

42. Synergistic Effect of Excited State Property and Aggregation Characteristic of Organic Semiconductor on Efficient Hole‐Transportation in Perovskite Device

Author

Jo, Bonghyun, primary, Park, Hansol, additional, Kamaraj, Eswaran, additional, Lee, Sewook, additional, Jung, Bumho, additional, Somasundaram, Sivaraman, additional, Jeon, Gyeong G., additional, Lee, Kyu‐Tae, additional, Kim, Namdoo, additional, Kim, Jong H., additional, Kim, Bong‐Gi, additional, Ahn, Tae Kyu, additional, Park, Sanghyuk, additional, and Park, Hui Joon, additional

Published
2020
Full Text
View/download PDF

43. Enhancement of light-energy conversion efficiency by multi-porphyrin arrays of porphyrin-peptide oligomers with fullerene clusters

Author

Hasobe, Taku, Fukuzumi, Shunichi, kamat, Prashant V., Kuwabata, Susumu, Troiani, Vincent, Kongkanand, Anusorn, Solladie, Nathalie, Kim, Dongho, Ahn, Tae Kyu, and Kim, Seong Keun

Subjects
Peptides -- Optical properties, Oligomers -- Optical properties, Porphyrins -- Optical properties, Chemicals, plastics and rubber industries
Abstract

The study reports novel photovoltaic cells composed of phorphyrin-peptide oligomers and fullerene clusters, which are deposited on nanostructured SnO2 electrodes. It concluded that the formation of a molecular assembly between fullerene and multi-porphyrin arrays with a polypeptide backbone controls the electron transfer efficiency in the supramolecular complex, which is essential for the light-energy conversion.

Published
2005

44. OperandoSpectroscopic Observation of CO Oxidation on a Pt/TiO2Catalyst in NO–CO Mixtures under Dark and UV Illumination

Author

Park, Cheolwoo, Hwang, Ji Young, Eom, Won Hyun, Han, Jae Won, Kim, Hyo Won, Ahn, Tae Kyu, and Kim, Wooyul

Abstract

The importance of catalytic CO oxidation for exhaust gas processing has inspired the development of efficient and durable catalysts that can be operated at low temperatures, as exemplified by supported noble metals. However, most of the related studies have neglected the potential effects of co-present exhaust gas components, such as NO. Herein, we compared the performances of platinized and bare TiO2for the ambient-temperature (photo)catalytic oxidation of CO by O2in the co-presence of NO and used in situFourier transform infrared spectroscopy to elucidate the effects of platinization on the efficiency and mechanism of this oxidation. Catalytic CO oxidation was accompanied by competitive NO oxidation both in the dark and under ultraviolet (UV) illumination. In the dark, Pt/TiO2achieved a higher CO removal efficiency than bare TiO2, which was ascribed to the enhanced adsorption of O2and CO and the inhibition of NO overoxidation (mainly the oxidation of the monodentate nitrito form to the bidentate nitrate form). Under UV illumination, Pt/TiO2efficiently promoted CO oxidation at photocatalytically active sites (Pt0–CO) by suppressing NO overoxidation and increasing the reduction of NO to N2O. Hence, the enhanced CO oxidation performance of Pt/TiO2was due to its ability to control NO oxidation and reduction at ambient temperature, which presents a new strategy for the design of low-temperature CO oxidation catalysts.

Published
2022
Full Text
View/download PDF

48. Tandem Solar Cells: Wide‐Bandgap Perovskite/Gallium Arsenide Tandem Solar Cells (Adv. Energy Mater. 6/2020)

Author

Li, Zijia, primary, Kim, Tae Hak, additional, Han, Sung Yong, additional, Yun, Yeo‐Jun, additional, Jeong, Seonghwa, additional, Jo, Bonghyun, additional, Ok, Song Ah, additional, Yim, Woongbin, additional, Lee, Seung Hu, additional, Kim, Kangho, additional, Moon, Sunghyun, additional, Park, Ji‐Yong, additional, Ahn, Tae Kyu, additional, Shin, Hyunjung, additional, Lee, Jaejin, additional, and Park, Hui Joon, additional

Published
2020
Full Text
View/download PDF

50. Wide‐Bandgap Perovskite/Gallium Arsenide Tandem Solar Cells

Author

Li, Zijia, primary, Kim, Tae Hak, additional, Han, Sung Yong, additional, Yun, Yeo‐Jun, additional, Jeong, Seonghwa, additional, Jo, Bonghyun, additional, Ok, Song Ah, additional, Yim, Woongbin, additional, Lee, Seung Hu, additional, Kim, Kangho, additional, Moon, Sunghyun, additional, Park, Ji‐Yong, additional, Ahn, Tae Kyu, additional, Shin, Hyunjung, additional, Lee, Jaejin, additional, and Park, Hui Joon, additional

Published
2019
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results