Hyeon Jin Seo

Photocatalytic Degradation Effect of μ-Dielectric Barrier Discharge Plasma Treated Titanium Dioxide Nanoparticles on Environmental Contaminant

This study focused on the photocatalytic degradation effect of the μ-dielectric barrier discharge (μ-DBD) plasma treated titanium dioxide (TiO2) nanoparticles on environmental contaminant such as formaldehyde. TiO2 nanoparticles were treated by a μ-DBD plasma source with nitrogen gas. We analyzed the degradation of formaldehyde with the plasma treated TiO2 nanoparticles by UV-visible spectrophotometer (UV-VIS), and demonstrated that the photocatalytic activity of the μ-DBD plasma-treated TiO2 nanoparticles showed significantly high catalytic efficiency rather than without plasma treated TiO2 nanoparticles. Field emission scanning electron microscopes (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and water contact angle analyzer were used to measure the effects of photocatalytic degradation for the plasma treated TiO2 nanoparticles.

Improved Electrochromic Characteristics of a Honeycomb-Structured Film Composed of NiO

Color changes controlled by electronic energies have been studied for many years in order to fabricate energy-efficient smart windows. Reduction and oxidization of nickel oxide under the appropriate voltage can change the color of a window. For a superior nickel oxide (NiO) electrochromic device (ECD), it is important to control the chemical and physical characteristics of the surface. In this study, we applied polystyrene bead templates to nickel oxide films to fabricate a honeycomb-structured electrochromic (EC) layer. We synthesized uniform polystyrene beads using the chemical wet method and placed them on substrates to create honeycomb-structured NiO films. Then, the EC characteristics of the nickel oxide films with a honeycomb structure were evaluated with UV-Visible and cyclic voltammetry. FE-SEM and AFM were used to measure the morphologies of the nanostructures and the efficiencies of the redox reactions related to the specific surface area.

Fast dipping treatment for dense perovskite thin films

Many groups have tried to make a dense organi-inorganic hybrid perovskite layer with one-step process. And perovskite synthesis method with the diethyl ether has been attempted in their own ways, such as dropping, long time dipping and so on. However, the reports for the solar cell having inverted form, photo-voltaic devices using PEDOT:PSS as hole transport layer, are not enough. In this work, we made the dense perovskite layer through fast-dipping method that casted films was soaked into diethyl ether. We study on the morphology and electrical properties of Methyl ammonium lead iodide (MAPbI3) thin films. The solar cells were consisted with ITO/PEDOT:PSS/MAPbI3/PCBM/Ag. The device performance were investigated with solar-simulator. At the same time, morphology, optical properties and crystalline variations were investigated by field emission scanning electron microscopy (FE-SEM), UV-Vis spectroscopy and X-ray diffraction (XRD) analysis, respectively.