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A A Pasa - One of the best experts on this subject based on the ideXlab platform.
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quasi one dimensional nanostructured cobalt co intercalated Vanadium Oxide v2o5 peroxovanadate sol gel synthesis and structural study
Journal of Solid State Chemistry, 2015Co-Authors: D L Da Silva, Eduardo Ceretta Moreira, F T Dias, V N Vieira, Iuri S Brandt, A D C Viegas, A A PasaAbstract:Abstract Nanostructured cobalt Vanadium Oxide (V 2 O 5 ) xerogels spread onto crystalline Si substrates were synthesized via peroxovanadate sol gel route. The resulting products were characterized by distinct experimental techniques. The surface morphology and the nanostructure of xerogels correlate with Co concentration. The decrease of the structural coherence length is followed by the formation of a loose network of nanopores when the concentration of intercalated species was greater than 4 at% of Co. The efficiency of the synthesis route also drops with the increase of Co concentration. The interaction between the Co(OH 2 ) 6 2+ cations and the (H 2 V 10 O 28 ) 4− anions during the synthesis was suggested as a possible explanation for the incomplete condensation of the V 2 O 5 gel. Finally the experimental results points for the intercalation of Co between the bilayers of the V 2 O 5 . In this scenario two possible preferential occupation sites for the metallic atoms in the framework of the xerogel were proposed.
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orthorhombic phase formation in electrochemically grown Vanadium Oxide v2o5 nanofibers
Materials Chemistry and Physics, 2013Co-Authors: D L Da Silva, A A PasaAbstract:Abstract The inner structure of V 2 O 5 nanofibers synthesized by electrochemical deposition has been investigated by transmission electron microscopy (TEM) and selected area electron diffraction (SAED). The experimental results demonstrate that the fibers are formed by 2D orthorhombic layers of V 2 O 5 . The layers are formed along the plane ab stacked in the crystallographic direction c . Additionally the diffraction results indicate that the fibers grow preferentially along the (100) crystallographic plane with surface dominated by the plane (001). The formation of fibers is discussed in terms of the preferential growth along specific orientations in order to minimize the surface energy of the nanostructures.
Seong Jun Kang - One of the best experts on this subject based on the ideXlab platform.
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Optimization of Hole Injection and Transport Layers for High-Performance Quantum-Dot Light-Emitting Diodes
Journal of the Korean Physical Society, 2019Co-Authors: Jae Seung Shin, Jong Hun Yu, Seong Jun KangAbstract:High-luminance, efficient quantum-dot light-emitting diodes (QLEDs) have been achieved by optimizing the balance between the hole injection layer (HIL) and the hole transport layer (HTL). Different concentrations of Vanadium Oxide (v2o5) and poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(4-sec-butylphenyl)diphenylamine)] (TFB) solutions were used to form the efficient HIL and HTL, respectively, for the QLEDs. The hole injection and transport behavior was characterized by using hole-only devices (HODs). The QLEDs, which were prepared with 0.5 wt.% of v2o5 and 0.1 wt.% of TFB as HIL and HTL, respectively, showed a maximum current efficiency of 2.27 cd·A−1 and a maximum luminance of 71,260 cd·m−2. Moreover, the turn-on voltage of the device was as low as 2.2 V due to the efficient carrier injection and transport. The results provide useful information for fabricating high-performance QLEDs.
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Low-temperature and solution-processable inorganic hole injection layer for flexible quantum-dot light-emitting diodes
Current Applied Physics, 2019Co-Authors: Jong Hun Yu, Yeonjin Yi, Seong Jun KangAbstract:Abstract A low-temperature solution-processable inorganic Vanadium Oxide (v2o5) hole injection layer (HIL) was synthesized for flexible quantum-dot light-emitting diodes (QLEDs). Efficient hole injection characteristics were observed in the hole-only devices; furthermore, the process temperature of v2o5 was as low as 30 °C. We investigated the source of the efficient hole injection behavior using ultraviolet and x-ray photoelectron spectroscopy. The density of gap states was found to increase in accordance with process temperature reduction. Therefore, QLEDs with low-temperature solution-processable v2o5 HILs were fabricated on a glass substrate, which showed excellent characteristics. The maximum luminance and luminous efficiency of the device were 56,717 Cd/m2 and 4.03 Cd/A, respectively. Due to the low-temperature process of the v2o5 HIL, it was also possible to fabricate QLEDs on a flexible plastic substrate without mechanical or thermal deformation of the substrate. Our results suggest that the low-temperature v2o5 inorganic HIL is a feasible alternative to organic HILs for flexible QLEDs.
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A solution-processable inorganic hole injection layer that improves the performance of quantum-dot light-emitting diodes
Current Applied Physics, 2017Co-Authors: Sang-moo Lee, Dongguen Shin, Nam Kwang Cho, Yeonjin Yi, Seong Jun KangAbstract:Solution-processable Vanadium Oxide (v2o5) was used as an inorganic hole injection layer (HIL) to improve the performance and stability of quantum-dot light-emitting diodes (QLEDs). Non-acidic and non-hygroscopic v2o5solution was synthesized and spin-coated onto indium-tin-Oxide (ITO)/glass substrate to serve as an HIL for QLEDs. QLEDs with a v2o5HIL showed efficient hole injection and had improved luminous efficiency and life-time. Maximum luminance and luminous efficiency of QLEDs fabricated under ambient conditions were 12,603 cd/m2and 2.96 Cd/A, respectively. Photoelectron spectroscopy measurements were conducted to construct an energy level diagram of the QLEDs, and we found that the gap states of v2o5enabled efficient hole-injection from ITO into the devices through the v2o5HIL, resulting in enhanced luminance. These results suggest that solution-processable v2o5is a feasible alternative to organic HILs for high-performance QLEDs.
Feng Luan - One of the best experts on this subject based on the ideXlab platform.
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electrodeposition of Vanadium Oxide polyaniline composite nanowire electrodes for high energy density supercapacitors
Journal of Materials Chemistry, 2014Co-Authors: Feng Luan, Yat LiAbstract:To meet the increasing demand for high energy density supercapacitors, it is crucial to develop positive and negative electrodes with comparable energy density. Previous studies have primarily focused on the development of positive electrodes, while negative electrodes are relatively less explored. Here we report an electro-codeposition method to synthesize a high performance negative electrode composed of a Vanadium Oxide (v2o5) and polyaniline (PANI) composite. Scanning electron microscopy revealed that the composite film is composed of one-dimensional polymer chains. Energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) confirmed successful incorporation of v2o5 into PANI chains. Significantly, the v2o5–PANI composite nanowires exhibited a wide potential window of 1.6 V (between −0.9 and 0.7 V vs. SCE) and a maximum specific capacitance of 443 F g−1 (664.5 mF cm−2). The flexible symmetric supercapacitor assembled with this composite film yielded a maximum energy density of 69.2 W h kg−1 at a power density of 720 W kg−1, and a maximum power density of 7200 W kg−1 at an energy density of 33.0 W h kg−1. These values are substantially higher than those of other pure v2o5 or PANI based supercapacitors. Moreover, the assembled symmetric supercapacitor device showed an excellent stability with 92% capacitance retention after 5000 cycles. The capability of synthesizing high performance composite electrodes using the electro-codeposition method could open up new opportunities for high energy density supercapacitors.
D L Da Silva - One of the best experts on this subject based on the ideXlab platform.
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quasi one dimensional nanostructured cobalt co intercalated Vanadium Oxide v2o5 peroxovanadate sol gel synthesis and structural study
Journal of Solid State Chemistry, 2015Co-Authors: D L Da Silva, Eduardo Ceretta Moreira, F T Dias, V N Vieira, Iuri S Brandt, A D C Viegas, A A PasaAbstract:Abstract Nanostructured cobalt Vanadium Oxide (V 2 O 5 ) xerogels spread onto crystalline Si substrates were synthesized via peroxovanadate sol gel route. The resulting products were characterized by distinct experimental techniques. The surface morphology and the nanostructure of xerogels correlate with Co concentration. The decrease of the structural coherence length is followed by the formation of a loose network of nanopores when the concentration of intercalated species was greater than 4 at% of Co. The efficiency of the synthesis route also drops with the increase of Co concentration. The interaction between the Co(OH 2 ) 6 2+ cations and the (H 2 V 10 O 28 ) 4− anions during the synthesis was suggested as a possible explanation for the incomplete condensation of the V 2 O 5 gel. Finally the experimental results points for the intercalation of Co between the bilayers of the V 2 O 5 . In this scenario two possible preferential occupation sites for the metallic atoms in the framework of the xerogel were proposed.
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orthorhombic phase formation in electrochemically grown Vanadium Oxide v2o5 nanofibers
Materials Chemistry and Physics, 2013Co-Authors: D L Da Silva, A A PasaAbstract:Abstract The inner structure of V 2 O 5 nanofibers synthesized by electrochemical deposition has been investigated by transmission electron microscopy (TEM) and selected area electron diffraction (SAED). The experimental results demonstrate that the fibers are formed by 2D orthorhombic layers of V 2 O 5 . The layers are formed along the plane ab stacked in the crystallographic direction c . Additionally the diffraction results indicate that the fibers grow preferentially along the (100) crystallographic plane with surface dominated by the plane (001). The formation of fibers is discussed in terms of the preferential growth along specific orientations in order to minimize the surface energy of the nanostructures.
Noureddine Gabouze - One of the best experts on this subject based on the ideXlab platform.
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Investigation of Strongly Hydrophobic and Thick Porous Silicon Stain Films Properties
Silicon, 2019Co-Authors: Maha Ayat, Mohamed Kechouane, C. Yaddadene, M. Berouaken, Katia Ayouz, Luca Boarino, Noureddine GabouzeAbstract:Porous silicon (PSi) structures with strong hydrophobicity have been achieved by chemical etching of p-type silicon substrates in a solution based on hydrofluoric acid solution (HF) and Vanadium Oxide (v2o5). The surface morphology and microstructure of the elaborated structured silicon surfaces were investigated using Scanning Electron Microscope (SEM), contact angle and Fourier Transform Infrared spectroscopy (FTIR). The results show that the obtained structures exhibit hierarchically porous surfaces with porous pillars of silicon (PPSi) and an important hydrophobicity of the surface. The electrical properties of those PPSi structures were investigated in presence of 10 ppm of NO2 gas. The response time was about 30s at room temperature. Our results demonstrate that PPSi/Si are highly hydrophobic for long time and suitable for applications in the field of self-cleaning and may be a good candidate in elaborating practical NO2 sensors.
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Formation of nanostructured silicon surfaces by stain etching
Nanoscale Research Letters, 2014Co-Authors: Maha Ayat, Noureddine Gabouze, Luca Boarino, S. Belhousse, Rabah Boukherroub, Mohamed KechouaneAbstract:In this work, we report the fabrication of ordered silicon structures by chemical etching of silicon in Vanadium Oxide (v2o5)/hydrofluoric acid (HF) solution. The effects of the different etching parameters including the solution concentration, temperature, and the presence of metal catalyst film deposition (Pd) on the morphologies and reflective properties of the etched Si surfaces were studied. Scanning electron microscopy (SEM) was carried out to explore the morphologies of the etched surfaces with and without the presence of catalyst. In this case, the attack on the surfaces with a palladium deposit begins by creating uniform circular pores on silicon in which we distinguish the formation of pyramidal structures of silicon. Fourier transform infrared spectroscopy (FTIR) demonstrates that the surfaces are H-terminated. A UV-Vis-NIR spectrophotometer was used to study the reflectance of the structures obtained. A reflectance of 2.21% from the etched Si surfaces in the wavelength range of 400 to 1,000 nm was obtained after 120 min of etching while it is of 4.33% from the Pd/Si surfaces etched for 15 min.
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Electrical characterization of ethanol sensing device based on Vanadium Oxide/Porous Si/Si structure
Solid State Ionics, 2013Co-Authors: Katia Chebout, A. Iratni, Ahmed Bouremana, Aissa Keffous, Noureddine GabouzeAbstract:Abstract A gas sensing device based on Vanadium Oxide (v2o5)/Porous Si (PS)/Si structure has been used to detect ethanol vapor at different concentrations. The v2o5 thin films were deposited on porous silicon by sol-gel (Dip-coating) technique. The Vanadium Oxide has been produced from Vanadium alcOxide precursor. The capacitance–voltage (C–V) and conductance–voltage (G/ω–V) characteristics of Al/v2o5/PS/Si structure have been measured in the range from 1 Hz to 10 MHz frequency at room temperature in the presence of ethanol vapor. It is found that both C–V and G/ω–V of the capacitor are very sensitive to frequency and the sensor characteristics are modified in the presence of the gas. Conductance and capacitance measurements at low frequencies indicate the presence of interface states which can follow an alternating current (ac) signal that contributes to excess capacitance and conductance.
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Impedance Measurements of Ethanol Sensing with Vanadium Oxide / Porous Si / Si Structure
2012Co-Authors: Katia Chebout, A. Iratni, Ahmed Bouremana, Kawthar M’hammedi, Hamid Menari, Aissa Keffous, Noureddine GabouzeAbstract:The paper deals with a gas sensing device based on Vanadium Oxide (v2o5)/ Porous Si (PS) /Si structure used to detect Ethanol gas at different concentration. The v2o5 thin films were deposited on porous silicon by the sol-gel (Dip-coating) technique. The Vanadium Oxide has been produced from Vanadium alcOxide precursor. Currentvoltage and admittance characterizations show that the sensor characteristics are modified in the presence of gases. Conductance measurements at low frequencies indicate the presence of interface states. KeywordsVanadium Oxide; porous silicon; gas sensor.
