Improvement Of Electrical Properties Research Articles

Graphene Nanoplatelet and Multiwalled Carbon Nanotube Doping Effect on the Structural and Physical Properties of PolyVinyl Alcohol Composites

Polyvinyl alcohol (PVA) composite thin films were prepared using graphene nanoplatelets (GNPs) and multiwalled carbon nanotubes (MWCNTs) as carbon fillers (CFs). The resulting electrical, optical, mechanical, and structural changes caused by adding the CFs to the pure PVA matrix were characterized. The improvement of electrical, optical, and mechanical properties was interpreted in terms of the percolation theory. Depending on this interpretation, the percolation threshold values, and the critical exponential values of the related properties were calculated. It turns out that the measured mechanical and optical changes were compatible with the site percolation theory while the electrical conductivity was compatible with the classical percolation theory. X-ray diffraction (XRD) measurements were performed to correlate the physical properties with the structure of the PVA composite films. They revealed that the degree of crystallinity of the composites increased with the CF reinforcement and that MWCNT was more effective in improvement of the crystallinity of the PVA composites than GNP.

Nanoscale Investigation on the Improvement of Electrical Properties of Boron-Doped Diamond Nanostructures for High-Performance Plasma Displays

Nanoscale Investigation on the Improvement of Electrical Properties of Boron-Doped Diamond Nanostructures for High-Performance Plasma Displays

Fabrication of graphite-reinforced 6201Al matrix composite with simultaneous enhancement of mechanical and electrical properties by multi-pass friction stir processing

In this study, graphite-reinforced 6201 aluminum alloy matrix composites were fabricated by multi-pass friction stir processing. The mechanical properties and electrical conductivity of the composites were tested, the microstructure and composition of the composites were analyzed by scanning electron microscope and Raman spectroscopy. The results showed that the graphite-reinforced 6201Al matrix composite achieved simultaneous improvement of mechanical and electrical properties compared to the base material, with a 19.5 % increase in ultimate tensile strength and a 1.2 % increase in electrical conductivity. Microstructural and compositional analysis revealed that the graphite reinforcement in the composites was significantly fragmented during FSP, and its size decreased while the number of atomic layers reduced with increase in FSP passes. A directly bonded Al-C interface is observed between the graphite reinforcement and the matrix, and no interface products such as Al4C3 were generated. The graphite reinforcement in the matrix simultaneously serves as a hindrance to dislocation motion and the expansion of microvoids during the tensile process, thereby leading to an enhancement in the tensile strength of the composite. The improvement in the electrical conductivity of the composite is attributed to two factors. On one hand, the structure and properties of graphite-reinforced phase is transformed to be closer to graphene after the severe plastic deformation during FSP process. On the other hand, the directly bonded Al-C interface between the matrix and the reinforcement is able to transfer electrons across the interface.

Cu2SnS3 based photovoltaic structure with improved open circuit voltage for air stable self-driven enhanced NIR photodetection

Copper tin sulfide (Cu2SnS3) is an environmentally benign and economical semiconductor comprising earth-abundant, non-toxic elements with flexible optoelectronic properties for photovoltaic energy conversion and photodetection. The optimization of sulfurization temperature resulted in significant improvement in structure, morphology, elemental composition, optical and electrical properties. A substantial advancement in photovoltaic performance was achieved by integrating a thin layer of SnS and the same enhancement theoretically predicted using SCAPS-1D simulation. Photovoltaic structure with optimized monoclinic Cu2SnS3 as an absorber layer and thin SnS layer (Glass/FTO/CdS/SnS/Cu2SnS3/Ag) resulted in photovoltaic parameters: Voc = 415 mV, Jsc = 17.2 mA.cm−2, and PCE = 2.12 %. We demonstrate the first self-powered SnS/Cu2SnS3 based photodetector which delivers high detectivity of 1.41 × 1011 Jones under the illumination of an 840 nm laser with rapid rise and decay time of 10.2 and 10.1 ms, respectively. Economic and environmentally benign Cu2SnS3 thin films based photovoltaic structures will be beneficial for harvesting sustainable energy and paving a strong platform for self-powered, air-stable, and spectral selective photodetection.

Effect of cerium addition on microstructure, thermal and rheological properties of hypoeutectic Al-Ni alloy

The microstructure, mechanical properties, electrical/thermal conductivity, and rheological behavior of Al-5Ni alloy with different Ce contents were systematically investigated. The experimental results demonstrate that an appropriate addition of Ce reduces the recalescence and growth temperatures of the Al-Ni eutectic structure, resulting in a reduction in precipitation phase size and the formation of a spherical Al3Ni eutectic structure. It leads to improvement in electrical conductivity and mechanical properties. But excessive addition of Ce leads to the formation of slatted Al23Ce4Ni6 on the Al-Ni eutectic boundary, causing the samples with higher Ce content to exhibit lower strength and thermal conductivity. Additionally, the investigation of alloy viscosity indicates significant shear thinning behavior of Al-Ni alloys, which contributes to obtaining uniformly filled and good quality cast products. The variation of melt viscosity suggested that Ce elements could improve the morphology and distribution of α-Al precipitates in the alloy, leading to an increase in viscosity in a specific temperature range.

Highly conductive and mechanically strong metal-free carbon nanotube composite fibers with self-doped polyaniline

Individual carbon nanotubes (CNTs) have gained popularity as lightweight wire materials due to their high electrical conductivity and low density than that of copper wires. Despite intensive research on light-weight and highly conductive CNT fibers, the bulk properties of CNT assemblies are inferior to those of metal wires in terms of electrical conductivity. Herein, we propose a method to increase the specific electrical conductivity of CNT fibers with polyaniline (PANI). The structure and physical properties of the CNT fibers are precisely controlled by optimizing the PANI content through a simple and effective solution process. PANI is considered to enhance CNT orientation, decrease voids, and dope the CNT fibers, resulting in a better electron flow in the fibers. The developed composite fiber with 5 wt% PANI demonstrated remarkable specific electrical conductivity of 6,200 ± 160 S m2/kg (11.9 MS/m) (max: 6,360 S m2/kg), an improvement of 16% above as-spun CNT fiber. Simultaneously, the mechanical properties increased by 27%, yielding a high specific tensile strength of 2.63 ± 0.10 N/tex (5.05 GPa). Furthermore, the toughness improved to 79.5 J/g, approximately a 1.8 times improvement over that of the CNT fiber. The addition of a small amount of PANI to CNT fibers has led to significant improvements in electrical and mechanical properties, which can provide insights into research on the CNT fiber field.

DFT studies of physico-chemical, electronic and nonlinear optical properties of interaction between doped-fullerenes with non-steroidal anti-inflammatory drugs

The interactions of pristine fullerenes and Si-doped fullerenes with three non-steroidal anti-inflammatory drugs were performed by calculations from the density functional theory. The physico-chemical, thermodynamic, nonlinear optical, electronic properties and global reactivity descriptors were highlighted. Our results show that all our formed nanostructures are stable and that their synthesis is thermodynamically favorable. These nanostructures are electrophile and very reactive for a transport process in the body. The improvement in electrical conductivity and nonlinear optical properties show that these nanomaterials can also be used for nonlinear optical and electronic applications.

Tuning the structural, optical, electrical, and dielectric properties of PVA/PVP/CMC ternary polymer blend using ZnO nanoparticles for nanodielectric and optoelectronic devices

Nanocomposite films made of polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and carboxymethylcellulose (CMC) and filled with different concentrations of zinc oxide nanoparticles (ZnO NPs) were created using the solution casting technique. Investigation and discussion were conducted about the effect of ZnO NPs on the pure PVA/PVP/CMC mixture's structural, optical, and electrical features. According to transmission electron microscopy (TEM) and X-ray diffraction (XRD) examinations, the size of the ZnO NPs produced is between 6 and 17 nm and has a hexagonal phase. The X-ray studies of the filled films revealed that the crystallinity of the ZnO NPs has grown at the expense of the PVA/PVP/CMC matrix. According to Fourier Transform Infrared (FTIR) analysis, the main vibrational peaks of PVA, PVP, CMC, and Zn–O varied after filling randomly. For the pure blend, the UV/Vis-NIR transmittance spectra displayed a large absorption peak at 210 nm that could be attributed to the π→π* transitions. After filling, the prepared composites showed a significant decrease in the average transmittance percentage and the appearance of a new small peak at 370 nm that related to the absorption of ZnO NPs. The optical energy gap (Eg), calculated using the indirect and direct allowed transition, was discovered to be reduced as the ZnO NPs content increased. At room temperature, the samples' dielectric characteristics, impedance, and AC conductivity were investigated over a wide frequency range (10−1 to 107 Hz). When the ZnO NPs content was raised, it was seen that the AC conductivity, dielectric loss, and dielectric constant were enhanced. In order to determine the equivalent electrical circuit for each sample, Z′ and Z″ impedance components were analyzed. Due to these remarkable improvements in electrical and optical properties, these nanocomposite films are a potential competitor for use in optoelectronic devices like sensors.

Mitigation of Thermal Instability for Electrical Properties in CaZrO3-Modified (Na, K, Li) NbO3 Lead-Free Piezoceramics.

Lead-free ceramics 0.96(Na0.52K0.48)0.95Li0.05NbO3-0.04CaZrO3 (NKLN-CZ) are prepared by using the solid-state procedure and two-step synthesis technique. The crystal structure and thermal stability of NKLN-CZ ceramics sintered at 1140-1180 °C are investigated. All the NKLN-CZ ceramics are ABO3-type perovskite phases without impure phases. With the increase in sintering temperature, a phase transition occurs in NKLN-CZ ceramics from the orthorhombic (O) phase to the concomitance of O-tetragonal (T) phases. Meanwhile, ceramics become dense because of the presence of liquid phases. In the vicinity of ambient temperature, an O-T phase boundary is obtained above 1160 °C, which triggers the improvement of electrical properties for the samples. The NKLN-CZ ceramics sintered at 1180 °C exhibit optimum electrical performances (d33 = 180 pC/N, kp = 0.31, dS/dE = 299 pm/V, εr = 920.03, tanδ = 0.0452, Pr = 18 μC/cm2, Tc = 384 °C, Ec = 14 kV/cm). The relaxor behavior of NKLN-CZ ceramics was induced by the introduction of CaZrO3, which may lead to A-site cation disorder and show diffuse phase transition characteristics. Hence, it broadens the temperature range of phase transformation and mitigates thermal instability for piezoelectric properties in NKLN-CZ ceramics. The value of kp for NKLN-CZ ceramics is held at 27.7-31% (variance of kp < 9%) in the range from -25 to 125 °C. The results indicate that lead-free ceramics NKLN-CZ is one of the hopeful temperature-stable piezoceramics for practical application in electronic devices.

Deep UV transparent conductive Si-doped Ga2O3 thin films grown on Al2O3 substrates

β-Ga2O3 is attracting considerable attention for applications in power electronics and deep ultraviolet (DUV) optoelectronics owing to the ultra-wide bandgap of 4.85 eV and amendable n-type conductivity. In this work, we report the achievement of Si-doped β-Ga2O3 (Si:β-Ga2O3) thin films grown on vicinal α-Al2O3 (0001) substrates with high electrical conductivity and DUV transparency of promising potential as transparent electrodes. The use of Al2O3 substrates with miscut angles promotes step-flow growth mode, leading to substantial improvement of crystalline quality and electrical properties of the Si:β-Ga2O3 films. A high conductivity of 37 S·cm−1 and average DUV transparency of 85% have been achieved for 0.5% Si-doped film grown on a 6° miscut substrate. High-resolution x-ray and ultraviolet photoemission spectroscopy were further used to elucidate the surface electronic properties of the grown Si:β-Ga2O3 films. An upward surface band bending was found at the surface region of Si:β-Ga2O3 films. Interestingly, all the Si:β-Ga2O3 films have a very low work function of approximately 3.3 eV, which makes Si:β-Ga2O3 suitable materials for efficient electron injection. The present Si:β-Ga2O3 films with high conductivity, DUV transparency, and low work function would be useful as the DUV transparent electrode to develop advanced DUV optoelectronic devices.

Solution-Processable NiOx:PMMA Hole Transport Layer for Efficient and Stable Inverted Organic Solar Cells.

For organic solar cells (OSCs), nickel oxide (NiOx) is a potential candidate as the hole transport layer (HTL) material. However, due to the interfacial wettability mismatch, developing solution-based fabrication methods of the NiOx HTL is challenging for OSCs with inverted device structures. In this work, by using N, N-dimethylformamide (DMF) to dissolve poly(methyl methacrylate) (PMMA), the polymer is successfully incorporated into the NiOx nanoparticle (NP) dispersions to modify the solution-processable HTL of the inverted OSCs. Benefiting from the improvements of electrical and surface properties, the inverted PM6:Y6 OSCs based on the PMMA-doped NiOx NP HTL achieves an enhanced power conversion efficiency of 15.11% as well as improved performance stability in ambient conditions. The results demonstrated a viable approach to realize efficient and stable inverted OSCs by tuning the solution-processable HTL.

Improved thermoelectric performance by microwave wet chemical synthesis of low thermal conductivity SnTe

SnTe is a promising replacement for PbTe due to its non-toxicity and high thermoelectric conversion efficiency. However, it suffers from poor performance caused by the presence of tin vacancies and a wide energy gap between the light and heavy valence bands, as well as high thermal conductivity that inhibits its thermoelectric properties. In this work, complexes of in situ grown SnTe with Bi doping were synthesized by microwave wet chemical synthesis. The complex morphology of the micro-nanoparticles and the formation of holes after spark plasma sintering suppress phonon scattering and greatly reduce the lattice thermal conductivity of the system. The band structure and phonon dispersion of Bi doped SnTe were calculated by first principles, and the reasons for the improvement of electric transport properties and the decrease of thermal conductivity of SnTe were investigated, combined with mechanical properties and sound speed reduction. The effects of various mechanisms such as polycrystalline interfaces, point defects, complex morphologies, and phonon dispersion flat bands on phonon scattering are discussed in detail and the obtaining mechanism of low lattice thermal conductivity is understood.

The Influence of NiO Nanoparticles on Structural, Optical and Dielectric Properties of CMC/PVA/PEDOT:PSS Nanocomposites

The solution casting process was used to fabricate nanocomposite samples composed of carboxymethylcellulose (CMC), polyvinyl alcohol (PVA), poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and filled with varied concentrations of nickel oxide nanoparticles (NiO NPs). The effect of NiO nanoparticles on the structural, optical, and electrical properties of the pure CMC/PVA/PEDOT:PSS mixture was studied and discussed. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis revealed that the NiO NPs are cubic in phase and range in size from 10 to 55 nm. The XRD analysis of the incorporated films indicated that the NiO NPs crystallinity increased at expense of the CMC/PVA/PEDOT:PSS composites. Fourier Transform Infrared (FTIR) examination revealed the main absorption vibrational peaks of CMC, PVA, PEDOT:PSS, and Ni-O, whose intensities changed randomly after filling, revealing the intermolecular interaction between the nanocomposite components. The UV and visible range absorption spectra showed a sharp peak around 228 for the pure blend, which can be assigned to the π→π* transition. After being filled with NiO NPs, the nanocomposites produced displayed new peaks at 292 and 422 nm that steadily increased with increasing NiO NPs concentration. The optical energy gap (Eg) was computed, and it was discovered that when the NiO NPs content increased, the Eg decreased (from 4.88 to 4.06 eV). At room temperature and over a wide frequency range, between 10− 1 and 107 Hz, the samples’ impedance, AC conductivity, and dielectric qualities were examined. Increased NiO NPs content was seen to gradually enhance dielectric loss (up to 2255), and dielectric constant (up to 311). The AC conductivity of the filled samples is also enhanced and corresponds to Jonscher power law. By analysing impedance components of the Z*, the equivalent electrical circuit for each sample was determined. Because of the considerable improvement in optical and electrical properties, these composite films could compete for usage in optoelectronic applications.

Enhanced optical and electrical properties of narrow-bandgap cerium borate glasses and nanostructured glass-ceramics: influence of V2O5-incorporation

Improvement of optical and electrical properties of borate glasses is a great demand for upgrading optoelectronic devices. Additionally, the transformation of borate glasses to nanostructured glass-ceramics endows them with outstanding beneficial properties to widen their application range. Herein, novel borate glass compositions are synthesized by the facile melt quenching method. The influences of V2O5-incorporation and nanocrystallization on the structural, optical, and electrical properties of the investigated cerium borate glasses are studied. The heat-treatment process promotes the precipitation of CeO2 and VCeO4 nanocrystals in the glass network. Linear and high dependence of the band gap of the as-prepared glasses on the V2O5 concentration is observed. A narrow band gap (about 1.6), which lies in the range of ideal bandgaps for two-junction photovoltaic cell applications, is achieved. Strong absorption in the visible and/or UV regions is attained for the studied samples, which is beneficial to shield laser emissions (up to 794 nm) and/or protect against the hazard of UV radiation. High DC conductivity (about 3 × 10−6 S m−1) is approved for the glass sample containing V2O5 content of 10 mol%. The investigated glasses and nanostructured glass-ceramics are recommended as promising candidates for UV-protection Sunglasses, laser safety, visible light irradiation photocatalyst, and next-generation semiconductors.

Improvement of electrical properties in Bi compensated 0.33BaTiO3-0.67BiFeO3 ceramics prepared via spark plasma sintering

Improvement of electrical properties in Bi compensated 0.33BaTiO3-0.67BiFeO3 ceramics prepared via spark plasma sintering

Second harmonic generation and simplified bond hyperpolarizability model analyses on the intermixing of Si/SiGe stacked multilayers for gate-all-around structure

Si/SiGe stacked multilayers are key elements in fabrication of gate-all-around (GAA) structures and improvement of electrical properties, with the evolution of the Si/SiGe interfaces playing a crucial role. In this work, a model is developed based on the simplified bond hyperpolarizability model (SBHM) to analysis the anisotropic reflective second harmonic generation (Ani-RSHG) on a three-period stacked Si/Si1−x Ge x multilayer, which builds on Si(100) diamond structures. The C 4v symmetry of the Si(100) structure enables the second harmonic generation (SHG) contribution from the bonds to be simplified and the effective hyperpolarizabilities of the interfacial and bulk sources to be obtained. The effective interface dipolar and bulk quadrupolar SHG hyperpolarizabilities in the Si1−x Ge x sample with various Ge concentration profiles are modeled by interpreting the concentration of a component element as the probability of the element occupying an atomic site. On the basis of the developed model, the Ani-RSHG spectra of the as-grown samples with various Ge ratios for each layer and the samples annealed at 850 °C and 950 °C are analyzed to inspect the change in Ge distribution and its gradient in depth. The ani-RSHG analysis on as-grown samples showed difference in Ge distribution in samples with the multi Si/SiGe structure, which is not well observed in synchrotron x-ray diffraction (XRD) spectra. For the annealed samples, the response to changes in Ge concentration and its gradient in depth reveal the Si/Si1−x Ge x interface intermixing. Results of high-angle annular dark-field scanning transmission electron microscopy and energy dispersive x-ray spectroscopy agree well with the Ani-RSHG with SBHM findings. Compared with the Raman and synchrotron XRD spectra, the Ani-RSHG with SBHM simulation result demonstrates much better response to changes in compositions of the Si/Si1−x Ge x stacked multilayered structures, verifying the potential for characterizing the concentration distribution in stacked multilayered thin films for GAA structures.

Improvement of electrical properties of ZnO TFT with NbLaO-based stacked gate dielectrics

The double-stacked gate dielectrics (DSGD), which consisted of either NbLaO/Al2O3 or NbLaO/SiO2, were used to improve the electrical performance of zinc oxide thin-film transistor (ZnO-TFT) with single-layer NbLaO gate dielectric (SLGD). Compared to ZnO-TFT with SLGD, the ZnO-TFTs with DSGD exhibit better electrical performance, specifically for the device with the NbLaO/SiO2 DSGD, with an increase of the field-effect mobility from 5.77 cm2V[Formula: see text]s[Formula: see text] to 39.64 cm2V[Formula: see text]s[Formula: see text], an enhancement of the on/off current ratio by two orders of magnitude, a reduction of the subthreshold slope from 110 mV/decade to 70 mV/decade. The performance enhancements are attributed to a low root-mean-square surface roughness of less than 0.3 nm and a low trap-state density of less than [Formula: see text] cm[Formula: see text] (even [Formula: see text] cm[Formula: see text] for the NbLaO/SiO2 DSGD) in the bulk of the channel and at the ZnO/NbLaO interface. The results imply that ZnO-TFTs with DSGD have the potential for the application of high-resolution flat panel display.

Introduction of SWCNTs as a Method of Improvement of Electrical and Mechanical Properties of CFRPs Based on Thermoplastic Acrylic Resin.

The aim of this research was to improve the electrical and mechanical properties of carbon-fibre-reinforced polymers (CFRP) based on thermoplastic acrylic resin ELIUM®, by introducing single-walled carbon nanotubes (SWCNTs) into their structure. The laminates were fabricated using the infusion technique of infiltrating the carbon fabric with the mixture of acrylic resin and SWCNTs. The addition of SWCNTs improved the electrical conductivity through the thickness of the laminate by several times compared to the laminate without modification. No defects or voids were observed in the structure of the fabricated nanocomposites. The introduction of SWCNTs into the CFRP structure increased the Young's modulus, interlaminar shear strength and impact resistance. DMA analysis showed almost no change in the glass transition temperature of the fabricated SWCNT/CFRP nanocomposites compared to the reference laminate.

Investigation of properties of Ta-doped Ga2O3 films prepared with seed layers

Ga2O3 is a promising ultra-wide bandgap semiconductor as a feasible candidate for power electronics, photodetectors, and sensors. Controlling electrical properties through doping is the key to its application in semiconductor devices. In this work, Ta-doped Ga2O3 films were prepared by radio frequency (RF) magnetron sputtering with seed layers. Effects of the thickness of seed layers on the microstructure, morphology, optical and electrical properties of Ta-doped Ga2O3 films were investigated. The fabricated Ta-doped Ga2O3 films exhibited polycrystalline structure with uniform and smooth surface and high optical transmittance (＞80 %) in the visible light region. The results showed that seed layers with appropriate thickness (∼20 nm) is beneficial to the improvement of crystalline quality and electrical properties of Ta-doped Ga2O3 films.

Improvement of Electrical and Mechanical Properties of PLA/PBAT Composites Using Coconut Shell Biochar for Antistatic Applications

Biochar-based environment-friendly polymer composites are suitable substitutes for conventional non-biodegradable polymer composites. In this work, we developed polylactic acid (PLA)/polybutylene adipate-co-terephthalate (PBAT)/biochar (BC) composites with improved mechanical and electrical properties for antistatic applications. Coconut shell biochar was obtained through the pyrolysis of coconut shell in an inert atmosphere, and characterised using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), to investigate the morphology and structural properties. The biochar was converted to powder form, sieved to reduce the particle size (≤30 μm diameters), and melt-mixed with PLA and PBAT to form composites. The composites were extruded to produce 3D printing filaments and, eventually, 3D-printed tensile specimens. The tensile strength and tensile modulus of the 3D-printed PLA/PBAT/BC (79/20/1) composite with 1 wt% of biochar improved by 45% and 18%, respectively, compared to those of PLA/PBAT (80/20). The interfacial interaction between the biochar and polymer matrix was strong, and the biochar particles improved the compatibility of the PLA and PBAT in the composites, improving the tensile strength. Additionally, the electrical resistivity of the composite did reduce with the addition of biochar, and PLA/PBAT/BC (70/20/10) showed the surface resistivity of ~1011 Ω/sq, making it a suitable material for antistatic applications.