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510 results on '"Jyongsik Jang"'

502. Organic light emitting bistable memory device with high on/off ratio and low driving voltage.

Author

Sung Hyun Kim, Kyoung Soo Yook, Jun Yeob Lee, and Jyongsik Jang

Subjects
ELECTRIC potential, TRANSMISSION electron microscopy, SPECTROPHOTOMETERS, DIODES, ELECTRON transport, NANOPARTICLES
Abstract

Organic light emitting bistable memory devices (OLEBDs) with a dual function of organic light emitting diodes and organic memory devices were developed by using 0.5 nm thick MoO3 as an interlayer between hole injection layer and hole transport layer. The hole transport unit with MoO3 interlayer played a role of a memory unit as well as a hole transport unit. High on/off ratio over 1000 was obtained at a reading voltage of 1 V and driving voltage was lowered by MoO3. In addition, two different luminances were obtained at the same driving voltage by changing writing voltage of OLEBDs. [ABSTRACT FROM AUTHOR]

Published
2008
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503. Transparent organic bistable memory device with pure organic active material and Al/indium tin oxide electrode.

Author

Kyoung Soo Yook, Jun Yeob Lee, Sung Hyun Kim, and Jyongsik Jang

Subjects
FERROELECTRIC RAM, INDIUM compounds, OXIDE electrodes, NANOPARTICLES, CATHODES, CATHODE rays
Abstract

Transparent organic bistable memory devices (OBDs) were developed by employing indium tin oxide (ITO) as an anode and a cathode for OBD. A cathode structure of aluminum (Al)/ITO was used and bistability could be realized with pure polyphenylenevilylene based polymer active material without any metal nanoparticle. Transmittance of over 50% could be obtained in Al/ITO based OBD at an Al thickness of 10 nm, and an average on/off ratio around 100 was observed. [ABSTRACT FROM AUTHOR]

Published
2008
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504. Thiol containing polymer encapsulated magnetic nanoparticles as reusable and efficiently separable adsorbent for heavy metal ions.

Author

Seoyoun Shin and Jyongsik Jang

Subjects
*THIOLS, *POLYMERS, *NANOPARTICLES, *METAL ions
Abstract

Fe3O4–PEDOT core–shell nanoparticles were fabricated by acid treatment mediated seeded polymerization and applied for highly efficient separation of heavy metal ions from contaminated waste water with an external magnetic field. [ABSTRACT FROM AUTHOR]

Published
2007
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509. Fabrication of a novel polypyrrole/poly(methyl methacrylate) coaxial nanocable using mesoporous silica as a nanoreactor

Author

Jyongsik Jang, Byungkwon Lim, Jinwoo Lee, and Taeghwan Hyeon

Subjects
Materials science, technology, industry, and agriculture, Metals and Alloys, General Chemistry, Nanoreactor, Mesoporous silica, Polypyrrole, Poly(methyl methacrylate), Catalysis, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, chemistry.chemical_compound, Monomer, chemistry, Polymerization, visual_art, Polymer chemistry, Materials Chemistry, Ceramics and Composites, visual_art.visual_art_medium, Methyl methacrylate, Mesoporous material
Abstract

We report on the fabrication of a polypyrrole/poly(methyl methacrylate) coaxial nanocable through the sequential polymerization of methyl methacrylate and pyrrole monomers inside the channels of mesoporous SBA-15 silica, followed by the removal of the silica template.

510. Selective growth of layered perovskites for stable and efficient photovoltaics

Author

Gabseok Seo, Giulia Grancini, Pascal Schouwink, Kyung Taek Cho, Jucheol Park, Mohammad Khaja Nazeeruddin, Yonghui Lee, Germà Garcia-Belmonte, Jaehoon Ryu, Jyongsik Jang, Sanghyun Paek, Osbel Almora, Manuel Tschumi, Sung J. Heo, and Emad Oveisi

Subjects
High-power conversion efficiency (PCE), Materials science, Processing cost, 02 engineering and technology, 010402 general chemistry, 7. Clean energy, 01 natural sciences, Stack (abstract data type), Photovoltaics, Environmental Chemistry, Thermal stability, Perovskite (structure), Renewable Energy, Sustainability and the Environment, business.industry, Perovskite solar cells (PSCs), Energy conversion efficiency, Photovoltaic system, Molecularly engineering, 021001 nanoscience & nanotechnology, Pollution, 0104 chemical sciences, Nuclear Energy and Engineering, Photostability, Three-dimensional (3D), 13. Climate action, Optoelectronics, 0210 nano-technology, business, Layer (electronics)
Abstract

Perovskite solar cells (PSCs) are promising alternatives toward clean energy because of their high-power conversion efficiency (PCE) and low materials and processing cost. However, their poor stability under operation still limits their practical applications. Here we design an innovative approach to control the surface growth of a low dimensional perovskite layer on top of a bulk three-dimensional (3D) perovskite film. This results in a structured perovskite interface where a distinct layered low dimensional perovskite is engineered on top of the 3D film. Structural and optical properties of the stack are investigated and solar cells are realized. When embodying the low dimensional perovskite layer, the photovoltaic cells exhibit an enhanced PCE of 20.1% on average, when compared to pristine 3D perovskite. In addition, superior stability is observed: the devices retain 85% of the initial PCE stressed under one sun illumination for 800 hours at 50 1 C in an ambient environment.

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