Yongsok Seo

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We report a simple method to prepare hierarchically structured TiO(2) spheres (HS-TiO(2)), using an electrostatic spray technique, that are utilized for photoelectrodes of highly efficient dye-sensitized solar cells (DSSCs). This method has an advantage to remove the synthesis steps in conventional sol-gel method to form nano-sized spheres of TiO(2)(More)
A model capable of describing the flow behavior of electrorheological (ER) suspensions under different electric field strengths and over the full range of shear rates is proposed. Structural reformation in the low shear rate region is investigated where parts of a material are in an undeformed state, while aligned structures reform under the shear force.(More)
A low-energy Ar+ ion beam was used to modify the surface of a polyetheretherketone (PEEK) film. The modification reaction proceeded with or without oxygen gas injected during the irradiation. The surface functional groups of the modified PEEK were confirmed with X-ray photoelectron spectroscopy as increasing various oxygen-containing functional groups. The(More)
Hierarchically structured TiO2 (HS-TiO2) was prepared on a flexible ITO-PEN (polyethylene naphthalate) substrate via electrospray deposition using a commercially available TiO2 nanocrystalline powder in order to fabricate flexible DSSCs under low-temperature (<150 °C) conditions. The cell efficiency increased when using flexible ITO-PEN substrates(More)
Core-shell-structured magnetic polystyrene (PS)/inorganic particles were fabricated by Pickering emulsion polymerization using nanosized Fe2O3 particles as a solid stabilizer. Scanning electron microscopy and transmission electron microscopy confirmed the synthesized PS/Fe2O3 particles to be comprised of a PS surface coated with Fe2O3 nanoparticles. The(More)
A two-step process for the sequential coating of magnetic carbonyliron (CI) particles with polystyrene (PS) and multiwalled carbon nanotubes (MWCNTs) was used to improve the sedimentation stability of micrometer-sized magnetic CI particles for magnetorheological (MR) applications under an applied magnetic field. The CI particles were initially coated with(More)
Taking into account of unique merits of conducting polymer/inorganic nanocomposites which play a positive effect in enhancing electrorheological (ER) performances, we adopted exfoliated clay sheet as a stabilizer to fabricate novel nano-scaled polyaniline (PANI) granules (PANI/clay) via pickering inverse emulsion polymerization in this study. Successfully(More)
The dispersion stability of soft magnetic carbonyl iron (CI)-based magnetorheological (MR) fluids was improved by applying a unique functional coating composed of a conducting polyaniline layer and a multiwalled carbon nanotube nest to the surfaces of the CI particles via conventional dispersion polymerization, followed by facile solvent casting. The(More)
The use of multiple donors in an active layer is an effective way to boost the efficiency of organic solar cells by broadening their absorption window. Here, we report an efficient vacuum-deposited ternary organic photovoltaic (OPV) using two donors, 2-((2-(5-(4-(diphenylamino)phenyl)thieno[3,2-b]thiophen-2-yl)thiazol-5-yl)methylene)malononitrile (DTTz) for(More)
We studied the effect of the surface functionalization and crystalline phase change of poly(vinylidene fluoride) (PVDF) films on their adhesion and piezoelectric properties. The surface modification of PVDF was carried out with ion beam and/or plasma treatment. These surface modifications were found to alter the interfacial strength between PVDF and metal(More)