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81.
Jia Xu Huilan Su Jie Han Ying Chen Weiqiang Song Yu Gu Won-Jin Moon Di Zhang 《Applied Physics A: Materials Science & Processing》2012,108(1):235-238
In this paper, a convenient biomineralization technique has been developed to form and assemble flower-like zinc oxide (ZnO) on silk fibroin fiber (SFF). Therein, SFF functions as supporting substrate and reactive sites for the in situ generation of ZnO particles. The photoluminescence (PL) of the resulting nanocomposite ZnO/SFF is investigated extensively. The PL peaks are mainly in the visible region (red), which is different from the usual ZnO region (green and violet). As-prepared ZnO/SFF nanocomposites could be useful in the medical field, photoelectron transfer devices, biomolecular detection, and antibacterial agents. 相似文献
82.
Ruijin Yu Hongjuan Li Hailong Ma Caifeng Wang Huan Wang Byung Kee Moon Jung Hyun Jeong 《Journal of luminescence》2012,132(10):2783-2787
A thiogallate chalcogenide phosphor CaLaGa3S7:Eu2+ was synthesized by a solid-state reaction at 950 °C in a H2S atmosphere. The photoluminescence excitation,emission spectra, concentration quenching, fluorescence lifetime, and thermal quenching process of the phosphor were investigated in detail. It was found that the synthesized phosphor emitted intense and broadband yellowish-green light with a peak at 554 nm. Thus, the proposed phosphor is suitable for the development of blue or near UV LED. The critical dopant concentration of Eu2+ (Rc=15 Å) per unit formula was found to be 0.15 mol. At room temperature, the fluorescence lifetime of Eu2+ in CaLaGa3S7 was found to be 0.216 μs. The activation energy for thermal quenching was 0.29 eV. The chromaticity coordinates of our phosphor is very close in color to Y3Al5O12:Ce3+. Therefore, CaLaGa3S7:Eu2+ can be a good alternative as a yellowish-green phosphor and can be used for white light generation in phosphor-converted LEDs. 相似文献
83.
Hye Jin Lee Eun Ji Nam Jung-Je Woo Seung-Hyeon Moon Jaeyoung Lee 《Current Applied Physics》2012,12(5):1235-1238
The modification of perfluorinated proton exchange membranes (e.g. Nafion) utilizing a layer by layer (LbL) electrostatic assembly of oppositely charged biophilic polymers such as poly-l-lysine as positive layer and dsDNA as a negative layer is developed to protect the interface between the catalyst layer and the membrane in a low temperature fuel cell. Various physicochemical measurements including water uptake, proton conductivity and surface tension were investigated for both the as-received Nafion and the biopolymeric LbL modified Nafion. The smaller water contact angle and the less swelling characteristics of the biopolymer modified Nafion membrane was founded compared to that of as-received Nafion. This clearly indicates that the more hydrophilic surface of biopolymeric layers on Nafion plays an important role in the enhanced dimensional stability. In addition, a potential hypothesis explaining the higher proton conductivity from the LbL biopolymeric film coated Nafion is suggested. 相似文献
84.
We have investigated the inverted poly (3-hexylthiophene):methano-fullerene [6,6]-phenyl C71-butyric acid methyl ester (P3HT:PC71BM) bulk heterojunction (IBHJ) solar cell with various n-type metal oxide nano particle layers on ITO and MoO3 anode buffer layer underneath Al. The IBHJ solar cell with a tin oxide nano particle layer shows the power conversion efficiency (PCE) of 3.1% and better stability compared to conventional BHJ solar cell. The PCE of this cell decreases by 3% after 2 months in ambient air while the other cells show more degradation. 相似文献
85.
Dielectric-breakdown-like forming process in the unipolar resistance switching of Ta2O5−x thin films
Moon Jee YoonShin Buhm Lee Hyang Keun YooSoobin Sinn Bo Soo Kang 《Current Applied Physics》2012,12(3):846-848
We report unipolar resistance switching (URS) in Ta2O5−x thin films. The current increased suddenly when we applied voltages up to 5-7 V to the pristine state of Pt/Ta2O5−x/Pt, Ni/Ta2O5−x/Pt, and Ti/Ta2O5−x/Pt cells. Just after this forming process, we observed a repetitive URS occurring independently of the electrodes. We found that the required voltages for the forming process did not depend on the top electrode type, but on the film thickness. These results suggest that the forming process is driven by a dielectric-breakdown-like phenomenon, and that URS occurs due to the formation and rupture of conducting channels inside the Ta2O5−x thin film. 相似文献
86.
Sul Lee Sunho Jeong Dongjo Kim Sookhyun Hwang Minhyon Jeon Jooho Moon 《Superlattices and Microstructures》2008
Nanocrystalline zinc oxide (ZnO) particles with controlled shapes and sizes were prepared at 180 °C by a simple polyol method. The amount of water and the method of addition played an important role in determining the characteristics of the synthesized particles. Rod-shaped ZnO particles with major axis lengths of ∼114 nm were obtained by heating the precursor solution, while equiaxial particles with average diameters of ∼24 nm were prepared by injecting water into hot precursor solution. Increasing the amount of water added to the precursor solution enlarged the aspect ratio of the rod-shaped particles and increased the particle size of the equiaxial particles due to enhanced hydrolysis and condensation of the Zn ion complex. 相似文献
87.
Kyung Moon Jung Kyung Hwan Kim Jung‐Il Jin Min Ju Cho Dong Hoon Choi 《Journal of polymer science. Part A, Polymer chemistry》2008,46(22):7517-7533
New deep‐red light‐emitting phosphorescent dendrimers with hole‐transporting carbazole dendrons were synthesized by reacting tris(2‐benzo[b]thiophen‐2‐yl‐pyridyl) iridium (III) complex with carbazolyl dendrons by DCC‐catalyzed esterification. The resulting first‐, second‐, and third‐generation dendrimers were found to be highly efficient as solution‐processable emitting materials and for use in host‐free electrophosphorescent light‐emitting diodes. We fabricated a host‐free dendrimer EL device with configuration ITO/PEDOT:PSS (40 nm)/dendrimer (55 nm)/BCP (10 nm)/Alq3 (40 nm)/LiF (1 nm)/Al (100 nm) and characterized the device performance. The multilayered devices showed luminance of 561 cd/m2 at 383.4 mA/cm2 (12 V) for 15 , 1302 cd/m2 at 321.3 mA/cm2 (14 V) for 16 , and 422 cd/m2 at 94.4 mA/cm2 (18 V) for 17 . The third‐generation dendrimer, 17 (ηext = 6.12% at 7.5 V), showed the highest external quantum efficiency (EQE) with an increase in the density of the light‐harvesting carbazole dendron. Three dendrimers exhibited considerably pure deep‐red emission with CIE 1931 (Commission International de L'Eclairage) chromaticity coordinates of x = 0.70, y = 0.30. The CIE coordinates remained very stable with the current density. The integration of rigid hole‐transporting dendrons and phosphorescent complexes provides a new route to design highly efficient solution‐processable materials for dendrimer light‐emitting diode (DLED) applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7517–7533, 2008 相似文献
88.
89.
A study on the effect of alkaline earth metal oxide on the activity and stability of nickel catalyst for carbon dioxide reforming
of methane was performed. When CaO, SrO, and BaO were used as supports, there was no difference in catalytic activity between
the catalysts made by coprecipitation and impregnation. However, when MgO was used as a support, the catalyst prepared by
coprecipitation showed superior activity than that made by impregnation. The higher activity of the catalyst made by coprecipitation
was due to the formation of solid solution consisting of nickel and magnesium. The formation of the solid solution enhanced
the dispersion of nickel and the resistance to coke formation. 相似文献
90.