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Solution-processed organic field-effect transistors with cross-linked poly(4-vinylphenol)/polyvinyl alcohol bilayer dielectrics
摘要： A single-layer gate dielectric cannot meet the requirements of large permittivity (k) and low surface polarity for fabricating low-operating-voltage, high-performance OFETs. Here, we have designed a bilayer gate dielectric consisting of a low-k cross-linked poly(4-vinylphenol) (CL-PVP) in contact with an active layer to provide a low polar surface and an underneath high-k polyvinyl alcohol (PVA) layer to ensure a high capacitance. The results show that the CL-PVP/PVA bilayer not only offers a smooth and uniform surface with low polarity and low surface energy as well as good solvent resistance for efficient carrier transport, but also possesses a relatively high capacitance and low leakage current for low threshold and operating voltages. We have utilized this bilayer dielectric to fabricate OFETs based on a conventional semiconducting polymer poly(3-hexylthiophene) (P3HT). High overall device performances have been achieved in the devices with a mobility of 0.1 cm2V-1s-1. The maximum density of trap states at the interface between the P3HT film and the CL-PVP/PVA bilayer is estimated to be 7.10×1012 cm-2 eV-1, further proving that this bilayer dielectric provides a high quality interface for P3HT. The CL-PVP/PVA bilayer is thus a promising candidate as a gate dielectric for fabricating high-performance organic or even organic-inorganic hybrid perovskite transistors by a solution processing technique.
关键词： P3HT OFETs,gate dielectrics,low-k CL-PVP/high-k PVA bilayer,dielectric and surface properties
更新于2025-09-19 17:15:36
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Modern control scheme for Z-Source inverter based PV power generation systems
摘要： Z-source inverter (ZSI) based photovoltaic power conversion system (PV-PCS) provides both the DC link voltage boost and DC-AC inversion in single stage with added features. Traditional maximum power point tracking (MPPT) control algorithm generates the required shoot-through interval to output maximum power to the Z-network. At this instant, the voltage across Z-source capacitor is equal to the MPP voltage of PV array. The capacitor voltage cannot be further increased if it is demanded by the load. This paper presents an improved MPPT control algorithm along with modified MPPT algorithm to achieve both the MPPT as well as capacitor voltage control at the same time. Development and implementation of the proposed algorithm has been carried out by Matlab/Simulink software and the results are provided.
关键词： maximum power point tracking (MPPT),Z-source inverter (ZSI),capacitor voltage control (CVC),pulse width modulation (PWM),photovoltaic array (PVA)
更新于2025-09-19 17:15:36
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Effect of annealed ZnS nanoparticles on the structural and optical properties of PVA polymer nanocomposite
摘要： PVA/ZnS nano-composites were prepared by both thermolysis and casting procedures. The influence of annealing temperature of ZnS nano filler on the structure properties of composite films was studied by x-ray diffraction technique and Fourier transform infrared (FTIR) techniques. X-ray analysis revealed that ZnS can be obtained with changing the annealing temperature up to 500 oC, above this temperature ZnS converted into ZnO. Moreover, the crystallite size of ZnS increased from 4 nm to 10 nm as the annealing temperature rose from 300 to 500 oC. The effect of crystallite size of nano filler on extinction coefficient, refractive index, band gap, dielectric constant, single-oscillator and the dispersion energies was studied in details using UV–vis. spectrophotometer technique. The photoluminescence technique (PL) showed that, PVA/annealed ZnS nano-composite films exhibited five sub-emissions spectra for ZnS annealed at 300°C and 400 oC while the sample contained ZnS annealed at 500 oC displayed two sub-emissions. PL intensity enhanced with increasing the crystallite size of ZnS nano particles.
关键词： PVA,size,structure,ZnS,annealed,optical
更新于2025-09-19 17:13:59
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Novel conducting PVA/Carbon quantum dots (CQDs) nanocomposite for high anti-electromagnetic wave performance
摘要： Novel conductive PVA/CQDs nanocomposite films were synthesized through the casting technique for the electromagnetic (EM) wave protection at microwave band. The surface morphology, thermal and mechanical properties were briefly studied. The SEM micrograph showed an excellent distribution, dispersion and a high adhesion property of the CQDs in the PVA chains. Also, DSC analysis showed an increase in the glass temperature (Tglass) from 83.2 °C for fresh PVA to 95.4 °C for 8 wt% of CQD and the increase in melting temperature from 215 °C for fresh PVA to 227.7 °C for the same CQDs concentration. It was found that Young's modulus is directly proportional to CQD nano-particles concentration in the nano-composites from 0.14 GPa for fresh PVA to 4.48 GPa for 8 wt% of CQDs. It was found that the strength at break increases, but the elongation declines with the increase of CQDs nano-particles. The EM shielding effectiveness (SE) of (PVA/CQDs) nanocomposite is measured in the microwave frequency range, and it is found around 36.8 dB with the CQDs concentration (8 wt%). Finally, the PVA/CQDs nano-composite is of promising potential applications in electronics and microwave devices at an affordable cost.
关键词： PVA,Mechanical properties,Electromagnetic shielding,Thermal properties,CQDs nano-particles
更新于2025-09-19 17:13:59
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Light scattering effect of polyvinyl-alcohol/titanium dioxide nanofibers in the dye-sensitized solar cell
摘要： In the present work, polyvinyl-alcohol/titanium dioxide (PVA/TiO2) nanofibers are utilized as a light scattering layer (LSL) on top of the TiO2 nanoparticles photoanode. The TiO2 nanoparticles decorated PVA/TiO2 nanofibers display a power conversion efficiency (PCE) of 4.06%, which is 33% higher than tio2 nanoparticles without LSL, demonstrating the incorporation of PVA/TiO2 nanofibers as LSL reduces the radiation loss and increases the excitation of the electron that leads to high PCE. The incorporation of PVA/TiO2 nanofibers as LSL also increases the electron life time and charge collection efficiency in comparison to the TiO2 nanoparticles without LSL.
关键词： power conversion efficiency,dye-sensitized solar cell,PVA/TiO2 nanofibers,light scattering layer,electron life time
更新于2025-09-19 17:13:59
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Facile synthesis, structure analysis and optical performance of manganese oxide-doped PVA nanocomposite for optoelectronic and optical cut-off laser devices
摘要： In the present work, successful manganese oxide (Mn2O3) nanoparticles (NPs) were synthesized by a combustion technique, while the casting process was employed for the manufacturing of polymer nanocomposites with various weights of Mn2O3 based on Poly(Vinyl Alcohol), PVA. Multiple methods such as X-ray diffraction (XRD), HR-TEM, EDAX, EDS, SEM, FT-IR, DTA analysis, optical spectroscopy from UV to IR regions, and optical reduction (CUT-OFF) setup were used to characterize the structural, elemental chemical analysis, morphological, optical properties, and cut-off laser characteristic of nanocomposite samples. Mn2O3 nanoparticles have a crystallite size of 22.08 nm as calculated using the Debye–Scherer formula from XRD, while the HR-TEM shows a spherical particle of size 30–38 nm range. EDAX spectra and EDS mapping were used to detect the elemental particles of the nanocomposite. The external morphology of the films by SEM images shows an increase in the agglomeration size of the cluster with the percentage of Mn2O3 nanoparticles in PVA. FT-IR spectra show excellent incorporation between the matrix of polymer and the Mn2O3 via the hydroxyl group. Moreover, with increasing the doping rate of nanoparticles, the thermal stability of PVA increased. A significant change of optical transmittance, absorption edge, Urbach energy, and transition bandgap have been observed due to the influence of Mn2O3. The comparison between the bandgap values that have been estimated from Tauc’s relation and thus resulting from optical dielectric loss indicates a direct allowed transition of electrons in the nanocomposites. The light is entirely UV–Vis absorbed by PVA with a high percentage of Mn2O3 nanoparticles. Moreover, the efficiency of the films to decrease the power of two laser beams (635 nm and 533 nm) has been observed. The flexible films of PVA with an elevated rate of Mn2O3 are considered a successful option for low-cost technologies of optical limiting.
关键词： Casting process,Combustion technique,PVA nanocomposite,Optoelectronic,Manganese oxide,Optical cut-off laser devices
更新于2025-09-19 17:13:59
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Effect of nanostructured metal oxides (CdO, Al2O3, Cu2O) embedded in PVA via Nd:YAG pulsed laser ablation on their optical and structural properties
摘要： The physiochemical properties of Polyvinyl Alcohol (PVA) film was enhanced by embedding with nanostructured metal oxides (CdO, Al2O3, and Cu2O) via one-pot and green method, nanosecond Nd:YAG pulsed laser ablation in liquids technique (PLAL). This process was carried by ablation of metal targets (cadmium, copper, and aluminum) immersed in PVA solution by high intensity pulsed laser in the focusing condition. The enhancing of the PVA properties were appeared by studying the structure, optical and morphology of the prepared films before and after embedding by several technique as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV–Visible, Photoluminescence (PL), Scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). From structural investigation, the XRD patterns showed a reduction of CdO, Al2O3, and Cu2O nanoparticles within PVA chain. From optical investigation, the interaction and the structural modifications occurred between PVA chains and each metal oxide nanoparticles appeared in stretching vibration bands, the optical energy band gap (Eg) values by using Tauc equation equaled to 2.33, 3.63, and 3.54 eV for the oxide of Cd, Al, and Cu, respectively, are a good agreement with previous work, and the Photoluminescence spectra showed decreasing in emission intensity in the case of embedding with metal oxides. From morphological investigation, the FE-SEM images showed a homogeneous distribution with spherical shape of metal oxides through the polymer of PVA. The qualitative and semi-quantitative elemental analysis of the prepared samples via EDX technique confirmed the embedding of the metal oxide in the PVA structure. This work helps to open the route to produce various properties of PVA by embedded with different nanostructured metal oxides.
关键词： Laser ablation,Al2O3,Nd:YAG,Metal oxides,nanosecond,PVA,Nanomaterials,CdO,Cu2O
更新于2025-09-16 10:30:52
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[IEEE 2019 2nd International Conference on Power Energy, Environment and Intelligent Control (PEEIC) - Greater Noida, India (2019.10.18-2019.10.19)] 2019 2nd International Conference on Power Energy, Environment and Intelligent Control (PEEIC) - Power Quality Enhancement of Soft Computing FLC MPPT Based Standalone Photovoltaic System
摘要： Single phase system has been secured with Photovoltaic system based on Fuzzy Logic Control based perturbed & observed (P&O) maximum power point tracking phenomenon with active power filter (APF) connected to a nonlinear load. The conventional Perturbed & Observed algorithm is used to achieve maximum power output from Photovoltaic array, Proportional Integral controller with positive sequence detector phase locked loop(PLL) synchronization are implemented to generate reference current. It is emplyed to generate switching signal for VSI in hysteresis band current controlled (HBCC). DC link of PWM converter is controlled with switch controlled of VSI inverter. In proposed work minimize harmonic distortion present in source current due to power electronic based nonlinear load. Total current harmonic distortion (THD) is reduced by shunt active power factor and power factor improve after compensation reactive power supplied by system reduce and active power of system increase. The system designed with MATLAB/SIMULINK 2015(a) platform.
关键词： Shunt Active Power Filter (SAPF),Photovoltaic Array (PVA),Maximum Power Point Tracking (MPPT),PWM Converter,Boost Converter,Fuzzy logic Control (FLC),Proportional Integral controller (PI)
更新于2025-09-16 10:30:52
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Structural, morphological, optical and dielectric properties of M <sup>3+</sup> /PVA/PEG SPE Films (M = La, Y, Fe or Ir)
摘要： Low band gap polymer complexes are promising due to its flexibility, and exhibiting electronic and optical properties of inorganic semiconductors. The effect of PEG on the physical properties of PVA was evaluated. Then, blend (PVA: PEG = 50:50) doped with rare earth (La or Y) and transition metal (Fe or Ir) chlorides to obtain solid polymer electrolyte films. XRD shows that adding PEG to PVA results in a new peak, 2θ = 23o with increased intensity as PEG ratio increases. However, doping with La3+, Fe3+ or Ir3+ eliminate this peak and decrease the crystallinity. SEM exhibits significant changes in the morphology of films. FTIR confirms miscibility between PVA & PEG and the complexation of the salts. The optical band gap (Eg) of PVA ~ 5.37 eV, decreased slightly by blending with PEG. While it decreased significantly to 2.64 eV and 2.78 eV after doping with Fe3+ or Ir3+. There are a consistency between Eg values obtained by Tauc's model and that obtained from the optical dielectric loss. The dielectric constant and loss, in temperature range 303–405 K & frequency range 1.0 kHz ‐ 5.0 MHz, indicate one or two relaxation peak(s) depending on the film composition. Accordingly, conduction mechanism varied between correlated barrier hopping and large polaron tunneling. The DC conductivity was strongly depend on the dielectric loss. The transition metal salts appear to be more effective than the rare earth ones in increasing σac of films to higher values that candidates them in semiconductors industry.
关键词： conduction mechanism,low band gap polymers,activation energy,PVA/PEG blend,rare earth metal complexation,solid polymer electrolyte
更新于2025-09-09 09:28:46
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U-shaped Microfiber Coupler Coated with Polyvinyl Alcohol Film for Highly Sensitive Humidity Detection
摘要： A probe-type relative humidity (RH) sensor was proposed and developed by combination of a U-shaped microfiber coupler (MFC) and a polyvinyl alcohol coating. Optical MFC is considered as an excellent kind of humidity sensor due to its highly sensitive to the environmental RI changes. By covering one layer of PVA film onto the surface of the waist region of the MFC, the sensitive of the proposed sensor was further increased. Experiment results indicated that the proposed sensor exhibited a good linear relationship between the wavelength and relative humidity over the 15% to 85%RH range and which also exhibited sensitivity are about 318.1 pm/%RH. And temperature experiment results showed that the temperature sensitivity of the proposed sensor is about 13.9 pm/℃ over the 20℃ to 50℃ rang, which indicated that the proposed sensor has the performance of being low temperature sensitive.
关键词： temperature insensitive,humidity detection,PVA film,highly sensitive,U-shaped microfiber coupler
更新于2025-09-09 09:28:46