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Ultrafast Transition of Non-Uniform Graphene to High-Quality Uniform Monolayer Film on Liquid Cu
摘要： It is essentially important to synthesize uniform graphene films with controlled number of layers since their properties strongly depend on the number of layers. Although chemical vapor deposition (CVD) on Cu has been widely used to synthesize large-area graphene films, the growth on solid and liquid Cu suffers from poor thickness uniformity with a great number of adlayers and difficulty in forming continuous film even after a long growth time of hours, respectively. Here, we found that non-uniform graphene film initially grown on solid Cu foil can rapidly transform into continuously uniform monolayer graphene film on liquid Cu within 3 min. Moreover, the films obtained show larger grain size, higher quality, better optical and electrical properties and better performance in organic light-emitting diode (OLED) applications than the original films grown on solid Cu foil. By using carbon isotope labeling, we revealed that the multilayer-to-monolayer transition of graphene on liquid Cu experiences etching-‘self-aligning’-coalescence processes. This two-step CVD method not only opens up a new way for the rapid growth of uniform monolayer graphene films, but also provides helpful information for the controlled growth of uniform monolayers of other 2D materials such as monolayer h-BN.
关键词： film,2D material,chemical vapor deposition,number of layers,graphene
更新于2025-11-14 17:03:37
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H2 Gas Sensor Based on Pd/ZnO Nanostructures Deposited on Tapered Optical Fiber
摘要： A novel H2 sensor using tapered optical fiber coated with Pd/ZnO nanostructures have been developed. The ZnO nanostructures was synthesized and deposited onto tapered optical fiber via chemical bath deposition (CBD) method. The ZnO was characterized by FESEM, XRD and EDX to confirm the material properties. It was discovered that the sensor is sensitive towards different concentrations of H2 in synthetic air at 180oC of operating temperature. By varying the deposition time of ZnO coating, different thickness of ZnO layer can be obtained. It was observed that with 280 nm thickness, the maximum absorbance response can be achieved. Further investigation with sensor sample of as-prepared and annealed was carried out to study its sensing performance towards H2. The absorbance response of 280 nm thickness of annealed Pd/ZnO has increased 64% as compared to as-prepared Pd/ZnO upon 1% H2 exposure in the synthetic air when measured in the visible to near infra-red optical wavelength. It can be concluded that the Pd/ZnO optical fiber sensor with thickness around 280 nm provided better sensitivity in sensing H2 at 180oC as compared to other thicknesses investigated.
关键词： Optical sensors,zinc oxide,sensing material
更新于2025-11-14 15:30:11
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Pressure effects in RF and DC sputtered Sb2Te3 thin films and its applications into solar cells
摘要： In this work we developed the synthesis and characterization of Sb2Te3 thin films, which were grown by RF as well as DC sputtering as a function of the deposition pressure (Pd), 5–15 mTorr. Sb2Te3 films were characterized through X-Ray Diffraction, Energy Dispersive Spectrometry (EDS), Scanning Electron Microscopy (SEM) and electrical resistivity measurements. As a part, contact layer, of the CdTe-based Solar Cell, Current-Voltage (I–V) as well as External Quantum Efficiency (EQE) measurements were carried out. Our results indicate that the radio-frequency sputtered Sb2Te3 are polycrystalline with predominant rhombohedral crystalline structure, whereas the DC-sputtered films crystallized mainly in the monoclinical structure. Both set of samples showed a resistivity of the order of 10?4 Ω-cm. Concerning the CdTe-based solar cell, the incorporation of the Sb2Te3 as a back surface film in the back contact improves the solar cell efficiency up to 8.01%, 10 mTorr pressures into the growth chamber, as compared to the CdTe-based solar cell, 4.82% efficiency, without the Sb2Te3 layer.
关键词： p+ material,CdTe solar cells,Sputtering RF and DC,Sb2Te3
更新于2025-11-14 15:15:56
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Performance optimization of bi-layer solar steam generation system through tuning porosity of bottom layer
摘要： In recent years, solar steam generation has attracted many attentions due to its potential applications in desalination, etc. In the present work, a bi-layer solar steam generation system is prepared by daubing carbon particles on the sintered sawdust film, which possesses an advantage of adjustable porosities compared to widely used wood. Then, the influence of the porosity on the evaporation performance is explored. The experimental result indicates that: the porosity could significantly affect the water transportation in the film, and the water diffusivity increases almost linearly with the increase of the porosity. The evaporation efficiency increases with the increasing porosity, until the porosity reaches about 0.52 then decrease slowly. The positive effect of the increased water diffusivity and the negative effect of the increased thermal conductivity of the bottom film layer determine that the porosity of 0.52 is optimal for improving the evaporation efficiency. Under a solar light power of 1 kW·m?2, the optimal porosity gives an evaporation efficiency of 77.64%, which is comparable to the best performance of bi-layer systems reported in previous works. The conduction of heat through the bottom layer to the bulk water and the convection heat loss on the top surface contribute 83% to the total heat losses in the system, suggesting that the energy losses of these two modes should be further reduced in the future applications. Considering the accessible materials, easy preparation, low cost and high efficiency, we conclude that the 0.52-porosity system is suitable for being used as an efficient solar steam generation device.
关键词： Solar steam generation,Thermal conductivity,Solar energy,Porous material
更新于2025-11-14 15:14:40
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Copper sulfide nanoparticles as hole-transporting-material in a fully-inorganic blocking layers n-i-p perovskite solar cells: Application and working insights
摘要： One of the challenges in the field of perovskite solar cells (PSC) is the development of inorganic hole-transporting-materials (HTM) suitable for solution-processed deposition, in order to have cheaper, more stable and scalable devices. Herein, we report the synthesis and characterization of p-type copper sulfide nanoparticles for their application for the first time as a low-cost, fully-inorganic HTM in mesoscopic n-i-p PSC. By employing CuS combined with two different perovskites, CH3NH3PbI3 (MAPbI3) and (FAPbI3)0.78(MAPbBr3)0.14(CsPbI3)0.08 (CsFAMAPbIBr), very high current densities and fill-factors are observed, suggesting an effective hole-extraction happening at the CuS interface. Noticeable, our cells exhibit one of the highest power conversion efficiencies (PCE) in n-i-p configuration employing a sole solution-processed inorganic HTM via non-toxic solvents, leading to 13.47% and 11.85% for MAPbI3 and CsFAMAPbIBr, respectively. As a remark, such PCE values are only limited by a reduced open-circuit voltage around 0.8 V, due to different phenomena occurring at perovkite/CuS interface such as an increased non-radiative recombination, caused by considerable difference in valence band value, and the effect of CuS metallic character. Overall, these findings highlight CuS as an extremely cheap alternative to common organic HTMs and pave the way to new improvements employing this material in full-inorganic blocking layers PSC.
关键词： perovskite solar cells.,Copper sulfide,interfaces,inorganic hole-transporting-material
更新于2025-10-22 19:40:53
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An isogeometric analysis to identify the full flexoelectric complex material properties based on electrical impedance curve
摘要： In this paper, we present a new approach to identify all material parameters of flexoelectric materials based on electrical impedance curves. This approach combines an Isogeometric Analysis (IGA) formulation with a gradient-based optimization algorithm using the Method of Moving Asymptotes (MMA). The IGA formulation allows for efficient modeling of flexoelectricity taking advantage of the higher order continuity of IGA. The proposed methodology starts with determining preliminary real parts based on resonant modes in order to avoid local minima which gives the numerical impedance curves close to the experimental impedance curve. The results in the preliminary step are used as initial parameters of the refinement step to simultaneously determine both real and imaginary part by minimizing the difference between pseudo-experimental and numerical impedance curve. Some numerical examples are illustrated to show the good agreement between the numerical and pseudo-experimental impedance curves.
关键词： Complex parameters,Piezoelectric material,Flexoelectric material,Isogeometric analysis
更新于2025-09-23 15:23:52
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Photocatalytic activity of biosynthesized CeO2 nano particles
摘要： This paper focuses on a cost effective and environment friendly technique for green synthesis of cerium oxide (CeO2) nano particles from cerium (III) nitrate hexahydrate solution by co-precipitation method using the leaf extract of different species of Artemisia pallens which acts as reducing and capping agent. The prepared CeO2 nano particles were characterized by XRD, TEM, FTIR, UV–Vis spectroscopy. The Photocatalytic activity of the prepared ceria powders was determined by their ability to degrade Methylene blue solution under UV-light radiation. The photo degradation result observed with 10 mg/L ceria at pH = 11 for 180 min have highest output and pseudo 1st order rate constant was 0.983.
关键词： Nanoparticles,Photocatalysis,Electronic material,Cerium oxide
更新于2025-09-23 15:23:52
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Design and Analysis of Gate Engineered Dual Material Gate Double Gate Impact Ionization Metal Oxide Semiconductor
摘要： In this exposition, we have proposed the Dual Material Gate Double Gate Impact Ionization Metal Oxide Semiconductor (DMG DG IMOS) device with a gate engineered technique of Gate Stacking which is ordinarily used in MOSFET for performance augmentation. This paper compares the performance of four DG IMOS based devices i.e. Single Material Gate Double Gate IMOS (SMG DG IMOS), SMG Gate Stacked DG IMOS (SMG GS DG IMOS), DMG DG IMOS and DMG Gate stacked DG IMOS (DMG GS DG IMOS). The performance of all the devices has been investigated using 2-D simulations. The device structures of gate stacked devices have been developed with two gate oxides namely SiO2 and HfO2 and remaining parameters have been taken alike for all four devices. The doping concentration of source and drain regions for all four devices has been taken as 1020 cm?3 and the doping concentration of the intrinsic region has been taken as 1015 cm?3. The Gate Stacked devices showed better analog outcomes as compared to the other devices. The analog parameters evaluated include transconductance (gm), total gate capacitance (Cgg) and unity gain frequency (fT). The proposed design, DMG GS DG IMOS has been then analyzed for different channel lengths and dielectrics of gate oxide materials to optimize the gate engineered design for various applications.
关键词： Impact ionization MOS (IMOS),Analog and RF parameters,Dual Material Gate Double Gate IMOS,Gate engineering and gate stack
更新于2025-09-23 15:23:52
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A highly efficient fluorescent material based on rare-earth-modified polyhydroxyalkanoates
摘要： Fluorescent materials play an important role in biomedical fields. However, the main types of fluorescent materials suffer from several disadvantages especially the biotoxicity, which largely restrict its wider applications in biological fields. In this study, a highly efficient rare-earth-modified fluorescent material was successfully designed and fabricated based on polyhydroxyalkanoates, which are known as biodegradable and biocompatible material. A new Functional-PHA polymer was microbially synthesized by engineered Halomonas bluephagenesis and was used as a basal matrix to generate the rare-earth-modified PHA. N-acetyl-L-cysteine-grafted PHA (NAL-grafted-PHA) was first produced via a UV-initiated thiol-ene click reaction and the rare earth metal ions (Eu3+ and Tb3+) were subsequently chelated onto the NAL-grafted-PHA through the coordination effect. The composite material exhibited intense photoluminescence properties under UV laser excitation, indicating the excellent features as fluorescent material. The enhanced hydrophilicity and superior biocompatibility of rare earth-chelated PHA were confirmed, suggesting its great potential application value in biomedical fields.
关键词： Halomonas,photoluminescence,next generation industrial biotechnology,fluorescent material,polyhydroxyalkanoates,PHB,Rare-earth metal ions
更新于2025-09-23 15:23:52
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Enhancing pyroelectric properties in (Pb1-1.5La )(Zr0.86Ti0.14)O3 ceramics through composition modulated phase transition
摘要： Currently, there is an urgent need of extraordinary comprehensive pyroelectric materials for the wide application in detectors and energy harvesters. In this study, the (Pb1-1.5xLax)(Zr0.86Ti0.14)O3 (abbreviated as PLZT, x = 0.02, 0.03, 0.04 and 0.05) ceramics located in ferroelectric-antiferroelectric (FE-AFE) phase boundary were designed and synthesized by using conventional solid-state reaction method. The microstructures, phase structures, dielectric, ferroelectric, thermal depolarization and pyroelectric properties of the PLZT ceramics with different La content were investigated thoroughly. The XRD results show that the PLZT ceramics change from FE phase to AFE phase with increasing La content. The significant improvement of pyroelectric coefficient and figures of merit (FOMs) are achieved in the PLZT ceramics with the increase in La content because of the increased metastable ferroelectric phase under the application of electric field. The (Pb0.955La0.03)(Zr0.86Ti0.14)O3 (x = 0.03) ceramic exhibits not only high of and high depolarization temperature (Td) of 179 ℃ but also excellent FOMs with ???? = , ???? = , and ???? = 3 47 5 ???? ? . In addition, the highest of is achieved in (Pb0.94La0.04)(Zr0.86Ti0.14)O3 (x = 0.04) ceramic. These results demonstrate that the PLZT ceramics of x = 0.03 and 0.04 are promising candidates for pyroelectric applications.
关键词： ferroelectric/antiferroelectric material,energy harvesting,(Pb,La)(Zr,Ti)O3 ceramics,pyroelectric properties
更新于2025-09-23 15:23:52