[en] Geuk (Momordica cochinchinensis spreng) tropical fruits, which are produced in Jeju Island, Korea, well known for containing high levels of carotenoids and α-tocopherol. In this study, geuk fruits were separated two parts (pulp; yellow-orange and seed aril; red). The extracts of geuk fruits were simultaneously analyzed for carotenoids and α-tocopherol contents using HPLC. The results showed that lycopene contained as the highest content in both seed aril and pulp and seed aril (846.84 μg/g) had lycopene two times more than pulp (390.15 μg/g). On the other hand, β-carotene of pulp (29.43 μg/g) was seven times more than seed aril (211.32 μg/g). α-Tocopherol was contained higher in seed aril (252.15 μg/g) than pulp (201.60 μg/g). The extracts and major components of geuk fruits (β-carotene, lycopene and α-tocopherol) were evaluated antioxidant activity using DPPH and ABTS assay. In both tested antioxidant assay, the seed aril extract showed stronger activity than the pulp extract. Lycopene, was more efficient than β-carotene, was active similar with α-tocopherol. Owing to the geuk fruits have powerful antioxidants, such as lycopene, β-carotene and α-tocopherol, which suggest that geuk fruits in the diet or in functional food products might provide greater health beneficial effects.

[en] The durability of a dye-sensitized solar cell with flexible substrate (fDSSC) was improved by introducing a composite separator membrane (CSM) between the TiO₂ working electrode and the counter electrode (CE). The fDSSC was fabricated by replacing a typical fluorine-doped tin oxide glass substrate of the platinum CE with a flexible indium tin oxide-coated poly(ethylene naphthalate) substrate. The CSM was a triple-layered membrane composed of poly(ethylene terephthalate) nonwoven fabric between the poly(vinylidene fluoride-co-hexafluoropropylene) gel layers, which provided a sandwich-like structure. The fDSSC with the CSM exhibited relatively good electrolyte retention capability and improved interfacial contact between the components, affording an fDSSC with high energy conversion efficiency and stable long-term performance. The potential of a CSM as an efficient component for durable flexible energy devices is demonstrated.

[en] Solution-based indium gallium zinc oxide (IGZO)/single-walled carbon nanotubes (SWNTs) blend have been used to fabricate the channel of thin film transistors (TFTs). The electrical characteristics of the fabricated devices were examined. We found a low leakage current and a higher on/off currents ratio for TFT with SWNTs compared to solution-based TFTs made without SWNTs. The saturation field effect mobility (μ_sat) of about 0.22 cm²/Vs, the current on/off ratio is ∼ 10⁵, the subthreshod swing is ∼ 2.58 V/decade and the threshold voltage (V_th) is less than - 2.3 V. We demonstrated that the solution-based blend active layer provides the possibility of producing higher performance TFTs for low-cost large area electronic and flexible devices.

[en] We report inkjet-printed InGaZnO (IGZO) thin film transistors (TFTs). IGZO ink was prepared by dissolving indium nitrate hydrate, gallium nitrate hydrate and zinc acetate dihydrate into 2-methoxyethanol with additional stabilizers. The resulting films were inkjet-printed with a resolution of 300 dots per inch using droplets with a diameter of 40 μm, and a volume of 35 pl. The films exhibited high optical transparency in the visible range and had a polycrystalline phase of InGaO₃(ZnO)₂ after thermal annealing treatment. The chemical composition of this IGZO sample was also determined, and shown to have high stoichiometric characteristics of low oxygen deficiency. The TFTs with a conventional inverted staggered structure using inkjet-printed IGZO as an active channel layer had a field-effect mobility of ∼ 0.03 cm²/Vs in saturation region and an on-to-off current ratio greater than ∼ 10⁴.

[en] ZnO thin films were deposited on (0001) Al₂O₃ substrates depending on oxygen partial pressure by pulsed laser deposition. Optical properties of ZnO were investigated by photoluminescence (PL). The relationship between PL and electron concentration has been investigated. Origin of the dominant ultraviolet (UV) emission in ZnO thin film measured at room temperature was identified as a free electron-neutral-acceptor transition (eA⁰) through temperature dependence of PL measurement. The UV emission intensity at room temperature is related to variation of electron concentration because a free-electron-neutral-acceptor transition (eA⁰) as origin of UV emission at room temperature is related to impurity concentration of ZnO

[en] In this study, the structural, optical, and electrical effects of Hf incorporation as a function of Hf atomic concentration were investigated using the solution process. Increases of Hf incorporation in Hf-InZnO (HIZO) thin films were associated with segregation of each element, and enhancement of optical bandgap energy and absorbance. We suggested that Hf could replace Ga as a carrier suppressor in the InZnO (IZO) system due to its low standard electrode potential, a property that reflects the oxidizing tendency of a metal cation. We observed that even small doses of Hf also resulted in the effective reduction of the carrier concentration in the IZO system. An increase of Hf incorporation in HIZO TFTs caused electrical properties including on-current, threshold voltage, and subthreshold swing to decrease, shift positively, and increase, respectively.

[en] Indium tin oxide (ITO) thin films were prepared by pulsed laser deposition (PLD) on glass substrate at room temperature. Structural, optical, and electrical properties of these films were analyzed in order to investigate its dependence on oxygen pressure, and rapid thermal annealing (RTA) temperature. High quality ITO films with a low resistivity of 3.3 x 10^-4 Ω cm and a transparency above 90% were able to be formed at an oxygen pressure of 2.0 Pa and an RTA temperature of 400 deg. C. A four-point probe method, X-ray diffraction (XRD), atomic force microscopy (AFM), and UV-NIR grating spectrometer are used to investigate the properties of ITO films

[en] Highlights: • The range of SLM process condition to achieve over 99.5% relative planar density of SUS316L. • Correlation study between microstructural, mechanical and chemical properties of SUS316L according to the high density process conditions for SLM. • Locally property tuning of SUS316L part by controlling the process condition of SLM selectively. The effects of laser energy density on microstructural, mechanical properties, and chemical composition of stainless steel 316 L (SUS316L) parts fabricated by selective laser melting (SLM) technology were studied. Total 36 specimens were fabricated under the range from 1.3 to 46.7 J/mm³. The process conditions to achieve over 99.5% ± 0.1% relative planar density were obtained, and the mechanism of tunable mechanical properties was investigated by understanding the correlation between the microstructure and chemical composition according to the energy density. As the energy density increased, tensile properties were decreased with grain growth and the concentrations of light elements were increased by accelerating dissolution. As the concentrations of light elements increased, the mechanism of destructive behavior changed from ductile fracture to brittle fracture and it caused that the hardness was improved. Consequently, it was necessary to control the energy density from 9.34 to 23.98 J/mm³ in order to fabricate SUS316L parts of high strength and high elongation characteristics by SLM method.

[en] Highlights: • The hardness and strength of pure titanium fabricated by SLM were increased with increasing the laser power. • During the SLM processing, the concentrations of oxygen and nitrogen in the SLM parts were increased. • The oxidation and nitriding were thermodynamically possible under SLM. - Abstract: This study analyzed the variation of mechanical properties and its causes with increasing the laser power in the fabrication of pure titanium by selective laser melting (SLM). SLM samples were fabricated using commercially pure titanium grade 1 powder when the scan speed was 1000 mm/s and the laser power as 120, 200, 280, 360, and 440 W, respectively. As the laser power increased, the hardness and strength of the samples increased gradually. During the SLM processing, the concentrations of oxygen and nitrogen in the SLM samples were increased, which resulted in the increase of hardness and strength. The SLM equipment used in this study removed oxygen in the chamber by flowing high purity argon gas and fabricates the sample while preserving the oxygen concentration in the atmosphere to 0.2%. Evaluating the possibility of oxidation and nitriding during the SLM process by thermodynamic analysis, it was found that the process occurred under conditions in which temperature and residual oxygen and nitrogen partial pressure led to oxidation and nitriding.

[en] Characteristics of oxide semiconductor thin film transistor prepared by gravure printing technique were studied. This device had inverted staggered structure of glass substrate/MoW/SiNx/ printed active layer. The active layer was printed with precursor of indium gallium zinc oxide solution and then annealed at 550 ^oC for 2 h. Influences of printing parameters (i.e. speed and force) were studied. As the gravure printing force was increased, the thickness of printed film was decreased and the refractive index of printed active layer was increased. The best printed result in our study was obtained with printing speed of 0.4 m/s, printing force of 400 N and the thickness of printed active layer was 45 nm. According to AFM image, surface of printed active layer was quite smooth and the root-mean square roughness was approximately 0.5 nm. Gravure printed active layer had a field-effect mobility of 0.81 cm²/Vs and an on-off current ratio was 1.36 x 10⁶.