Papers by Keyword: TPD

Abstract: The physical and chemical characterize of quantum dots (QDs) extensively depend upon the optical and morphological factors such as size and shape. The zinc selenide (ZnSe) quantum dots (QDs) have been prepared by chemical method and used to fabricate quantum dot hybrid junction devices with different types of organics polymers. The optical studies illustrate that the band gap value from the photoluminescence (PL) with high intensity of these QDs is found about 3.1 eV. The electroluminescence's (EL) hybrid devices were demonstrated by room temperature PL and electroluminescence (EL). Current-voltage (I–V) characteristics indicate that the output current is good compared to the few voltages (5.5 V) used which gives good results to get a generation of white light. The EL spectrum reveals a broad emission band covering the range from 350 - 700 nm. The emissions producing this white luminescence were recognized depending on the chromaticity coordinates (CIE 1931). The correlated color temperature (CCT) was found to be about 5759, 3500 and 3498 K for ITO/TPD/ZnSe, ITO/PPV/ZnSe and ITO/PEDOT/ZnSe QDs respectively. Fabrication of EL- hybrid devices from semiconductors materials (ZnSe QDs) with holes injection organic polymer (TPD, PPV and PEDOT) was effective in white light generation.

Abstract: Quantum dots of CdSe, CdS and ZnS QDs were prepared by chemical reaction and used to fabricate organic quantum dot hybrid junction device. QD-LEDs were fabricated using layers of ITO/TPD: PMMA/CdSe/Alq₃, ITO/TPD: PMMA/CdS/Alq₃ and ITO/TPD: PMMA/ZnS/Alq₃ devices which prepared by phase segregation method. The hybrid white light emitting devices consists, of three-layers deposited successively on the ITO glass substrate; the first layer was of N, N’-bis (3-methylphenyl)-N, N’-bis (phenyl) benzidine (TPD) polymer mixed with polymethyl methacrylate (PMMA) polymers. The second layer was QDs while the third layer was tris (8-hydroxyquinoline) aluminium (Alq₃). The results of the optical properties show that the prepared QDs were nanocrystalline with defects formation. The calculated of energy gaps from photoluminescence (PL) spectrometer were 2.38, 2.69 and 3.64 eV for CdSe, CdS and ZnS respectively. The generated white light has acceptable efficiency using confinement effect which makes the energy gap larger, so that the direction of the light sites are toward the center of white light color. The hybrid junction devices (EL devices) were characterized by room temperature PL and electroluminescence (EL). Current-voltage (I–V) characteristics indicate that the output current is good compared to the few voltages ( 8-10.3 V) used which gives acceptable results to get a generation of white light. The EL spectrum reveals a broad emission band covering the range from 350 - 700 nm. The emissions causing this white luminescence were identified depending on the chromaticity coordinates (CIE 1931). The correlated color temperature (CCT) was found to be about 6250, 5310 and 5227K respectively. Fabrication of EL-devices from semiconductors material (CdSe, CdS and ZnS QDs) with hole injection organic polymer (TPD) and electron injection from organic molecules (Alq₃) was effective in white light generation

Abstract: The removal of SO2 and NO from flue gas could be achieved with high efficiency by using activated semi-coke through catalytic oxidation. In order to probe the interaction between SO2 and NO on the surface of activated semi-coke, the TPD study was carried out when NO and SO2 had adsorbed separately on the support surface or they were brought into the reaction of TPD simultaneously. The results showed that the activated semi-coke had two different alkaline adsorption sites and the surface of semi-coke was heterogeneous due to the appearance of overlap peak. What’s more, SCO process by using activated semi-coke should be placed after the process of desulfurization.

Abstract: Pure nanostructured LaFeO₃ with crystallite size of around 13 nm and specific surface area of 48 m²/g were prepared using high energy ball milling. 0.4, 2 and 5 wt% of Pd was impregnated on synthesized LaFeO₃. TPD-O₂, TPD-CO and TPR-H₂ were performed to find the effect of Pd loading on perovskite oxide properties.CO gas sensing properties of doped and pure formulation were investigated. These results showed that 2 wt% Pd had optimum response ratio which had a maximum response ratio of 1200% with respect to 100 ppm CO in air at 140°C.

Abstract: Magnesium oxide (MgO) films are utilized for the anti-plasma sputtering coating with excellent ability of secondary electron emission in plasma display panels (PDP). These properties are degraded by the impurities adsorbed on the film surface. Therefore, we should obtain impurity-free surface during the PDP manufacturing process. We have synthesized whisker and continuous film types of metal oxide using a chemical vapor deposition (CVD) method operated under atmosphere. In this study, a temperature programmed desorption method has been applied to detect residual species adsorbed on the surface of the present films in the ultra-high vacuum atmosphere. The amount of water adsorption was determined by this method.