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Piezoelectric and Dielectric Properties of ((K0.475Na0.495Li0.03)NbO3-0.003ZrO2)/PVDF Composites
摘要： The (K0.475Na0.495Li0.03) NbO3-0.003ZrO2 (KNNL-Z) ceramic was synthesized by the conventional solid-state reaction and (KNNL-Z)/PVDF composites were fabricated by hot-pressing process using polyvinylidene fluoride (PVDF) and KNNL-Z ceramic. The effects of the ceramic content on the crystalline structures, morphology, densities, dielectric and piezoelectric properties of (KNNL-Z)/PVDF 0–3 composites were systemically studied. The KNNL-Z ceramic possesses a perovskite phase with orthorhombic symmetry and the PVDF polymer mainly possesses a, b and c phases. Interestingly, the incorporation of the ceramic particles can decrease the crystallite size of the PVDF matrix. In addition, the b phase content increases and the a phase decreases when the ceramic particles are added. When the ceramic content increases from 40 wt.% to 80 wt.%, the relative fraction of b phase increases from 47.7% to 53.8%. Successful incorporation of ZrO2 into the KNN ceramic has been demonstrated by energy-dispersive x-ray spectroscopy and the most elements are homogeneously distributed in the composites. The dielectric and piezoelectric properties are found to be improved with the increase of KNNL-Z content. When 80 wt.% KNNL-Z is added, the dielectric permittivity reaches the value of 272 (100 Hz) at room temperature and the piezoelectric coefficient is 39 pC/N. After 30 days of aging, it is obvious that all the composites present a good stability of their piezoelectric property.
关键词： PVDF,0–3 composite,KNNL-Z,dielectric properties,piezoelectric properties
更新于2025-09-19 17:15:36
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Wearable piezoelectric nanogenerators based on reduced graphene oxide and in situ polarization-enhanced PVDF-TrFE films
摘要： PVDF-TrFE-based wearable nanogenerators were designed and fabricated with enhanced performances via reduced graphene oxides (rGO) and in situ electric polarization. Our laboratory-made polarization system may complete the in situ poling of PVDF-TrFE films in 5 min without heating, which has the advantages of high production efficiency, excellent piezoelectric performances, and favorable uniformity, compared to traditional poling approaches. The addition of rGO into PVDF-TrFE significantly improved the crystallinity of the b-phase PVDF-TrFE and enhanced the formation of hydrogen bonds via interaction of dipoles between rGO and PVDF-TrFE. This further improved the energy-harvesting performances of these piezoelectric nanogenerators with 1.6 times of the open-circuit voltage and 2 times of the power density than that of pure PVDF-TrFE-based devices. The high production efficiency and excellent piezoelectric performances of in situ polarized rGO/PVDF-TrFE make them of great potential for self-powered, wearable/portable devices.
关键词： Electronic materials,Reduced graphene oxide,PVDF-TrFE,Wearable piezoelectric nanogenerators,In situ polarization
更新于2025-09-19 17:15:36
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Effect of ionic liquid concentration on the photovoltaic performance of dye-sensitized solar cell
摘要： Quasi-solid-state electrolytes based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVdf-HFP), propylene carbonate (PC), 1,2-dimethoxyethane (DME) and different concentrations of 1-methyl-3-propylimidazolium iodide (MPII) salt were prepared. The highest room temperature conductivity of 4.6 x 10-3 S cm-1 was achieved with 1.0M MPII. The effect of MPII on the conductivity was discussed on the basis of number free ions. The number of free ions were estimated by impedance spectroscopy method. DSSC at 1.0M MPII shows the conversion efficiency, η of 3.70% with short-circuit current density, Jsc of 8.65 mA cm-2, open circuit voltage, Voc of 641 mV and a fill factor, FF of 66%.
关键词： MPII,Electrolyte,Quasi-solid state,PVdF-HFP,Dye-sensitized solar cells
更新于2025-09-12 10:27:22
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Polymeric Electrolyte Thin Film for Dye Sensitized Solar Cells Application
摘要： In this paper, the possibility of replacing liquid electrolyte in a dye sensitized solar cells with a thin film of conductive polymer material was investigated. Liquid electrolyte in the construction of dye sensitized solar cells leaks and evaporates and leads to corrosion of the electrode, which affects negatively on the conversion efficiency of solar radiation to electricity. The research focuses on the doping of the PVDF-HFP polymer by potassium iodide to improve its electrical conductivity and the development of thin film deposition technology for use in solar cells. Using a scanning electron microscope, with the increase of potassium iodide, changes in the surface morphology of PVDF-HFP were measured. Using a Keithley meter, it was investigated that an increased content of potassium iodide led to a reduction in resistance. The electrical conductivity of the tested samples was calculated. In order to test the suitability of developed materials for application in the construction of photovoltaic cells, a series of dye-sensitized solar cells ITO/TiO2/dye/active layer/Al were prepared. The active layer is made from pure PVDF-HFP and doped with potassium iodide. As a reference solar cell, a standard dye sensitized solar cell with a liquid electrolyte and a counter electrode was also prepared.
关键词： PVDF-HFP,Dye sensitized solar cells,Polyelectrolyte
更新于2025-09-12 10:27:22
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Experimental Study on Fluorine Release from Photovoltaic Backsheet Materials Containing PVF and PVDF during Pyrolysis and Incineration in a Technical Lab-Scale Reactor at Various Temperatures
摘要： With a sharp increase in photovoltaic (PV) installations across the world, PV waste is now a relatively new addition to the e-waste category. From 45,000 tonnes in 2016, the PV waste stream is rapidly increasing and is projected to reach 60 million tonnes by 2050. Backsheets are composite structures made from several material layers of polymer, adhesive, and primer. Widely used PV backsheets can be classified into three core types: (a) KPK (Kynar?/PET/Kynar?), (b) TPT (Tedlar?/PET/Tedlar?), and (c) PPE (PET/PET/ethylvinylacetate). Kynar? and Tedlar? are based on polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVF), respectively. PPE backsheets are fluorine-free composites made primarily from PET. With increasing focus on the end-of-life (EoL) handling of PV waste, the handling of fluoropolymers, which is largely unexplored, requires closer examination to avoid environmental damage. The aim of this study was to obtain information on the fluorine released from PV backsheet materials into the gas phase during combustion and pyrolysis as EoL pathways. Therefore, several experimental trials were conducted to measure fluorine transfer into the gas phase at 300 °C, 400 °C, 500 °C, and 900 °C (for pyrolysis) and at 750 °C, 850 °C, and 950 °C (for incineration).
关键词： fluoropolymers,end-of-life treatment,PVDF/PVF,PV backsheet,pyrolysis and incineration
更新于2025-09-12 10:27:22
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Conducting polyaniline decorated in-situ poled Ferrite nanorod-PVDF based nanocomposite as piezoelectric energy harvester
摘要： PVDF-metal oxide based piezo-nanocomposite is an promising substitute of flexible nanogenerator. Herein, a ternary nanocomposite system Zinc Ferrite nanorod/ Polyvinylidenefluoride (PVDF)/ Polyaniline (PANI) nanochains was presented as alternative energy harvesting material. The inherent problem of low short-circuit current and high internal resistance of the nanocomposite was minimised by introducing a third phase cost-effective conducting supplementary filler, PANI nanochain.PANI assist to overcome the local dielectric dissimilarity by easy formation of conduction pathways via decolalization of π-electrons present in the benzene ring and reduce the internal resistance of composite. Besides, it serves the role of dispersing agent by floating nanofillers throughout the volume and improves the homogeneity of filler distribution. Additionally, PANI reinforces composite with respect to stress accumulation and modulates the release behaviour by entangling with nanofillers by means of Vander Waals force and helps to stabilize the polar PVDF. This lead to an improvement in electro-mechanical response and piezo-response behaviour of nanocomposite. The nanocomposite exhibits a ~42 V ac open circuit voltage and short-circuit current density ～0.85 μA/cm2with an overall increase in power density 35% compare to its binary metal-oxide/PVDF nanocomposite counterpart in response to single finger tapping and releasing. The generated power was utilizedto illuminate twenty six number of red LEDs without any external energy storage unit. Also, the nanocomposite could charge up acommercial capacitor (10μF) within 115 s which can be used for alternative powersouce in self-powered devices and sensors.
关键词： PANI,capacitor charging,short-circuit current,PVDF-metal oxide based nanocomposite,conduction pathway,alternative energy harvesting
更新于2025-09-12 10:27:22
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Facile preparation and properties of polyvinylidene fluoride dielectric nanocomposites <i>via</i> phase morphology control and incorporation of multiwalled carbon nanotubes conductive fillers
摘要： A novel PVDF dielectric nanocomposite was achieved by controlling phase morphology and incorporating conductive ?llers simultaneously, and the mechanical, thermal, dielectric properties of the resultant dielectric nanocomposites were investigated. Mechanical analysis showed that incorporation of modi?ed MWCNTs (MWCNTs-COOH) in the PVDF nanocomposites resulted in signi?cant improvements on the tensile strength (Ts) and elasticity modulus (Em). When the ?ller content was 12 wt%, the Ts of MWCNTs-COOH/PVDF could reach 64.6 MPa. XRD test showed that the addition of MWCNTs-COOH and MWCNTs promoted the formation of β-phase of PVDF. DMA analysis showed that the glass-transition temperature of the PVDF nanocomposites slightly increases on loading of original MWCNTs and this effect was more pronounced on loading MWCNTs-COOH. The dielectric property analysis showed that the original MWCNTs were more likely to form local conductive networks in the PVDF matrix, promoting the electron displacement polarization, and improving the dielectric constant. When the contents of MWCNTs was 12 wt%, the percolation threshold was obtained and the dielectric constant (ε0) reached 286, which was 36 times of pure PVDF. Our work provides a simple way to fabricate polymer blends with excellent dielectric performances, good mechanical properties as well as good processing capability but low cost.
关键词： polyvinylidene ?uoride (PVDF),thermal performance,dielectric properties,multi-walled carbon nanotubes (MWCNTs),mechanical properties
更新于2025-09-11 14:15:04
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[IEEE 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC) - Waikoloa Village, HI (2018.6.10-2018.6.15)] 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC) - Cathodoluminescence Characterization of Semiconductor Doping at the Nanoscale
摘要： PVDF pyroelectric sensor was widely used in many fields. At present, the PVDF pyroelectric sensor has been applied for acoustic measurement. However, the effect of backing on the sensitivity of sensor was not particularly studied until now. In this paper, a Physical model was established in the finite element software. According to this model, the waveform of pyroelectric signal was predicted. By changing the parameters of the backing material, the influence of the backing on the sensitivity of the sensor was analyzed. It is confirmed that the Physical model is effective and the constant pressure heat capacity, attenuation coefficient and acoustic impedance of backing material directly affect the sensitivity of the sensor.
关键词： PVDF pyroelectric sensor,backing material,ultrasonic power,sensitivity
更新于2025-09-11 14:15:04
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β-Phase Crystallization of Poly(vinylidene fluoride) in Poly(vinylidene fluoride)/Poly(ethyl methacrylate) Blends
摘要： The nature of the crystalline phase of poly(vinylidene fluoride) (PVDF) in compatible blends with poly(ethyl methacrylate) (PEMA) was investigated by using X-ray diffraction (XRD), infrared microscopy (IR) and differential scanning calorimetry (DSC). The β phase of PVDF was observed after quenching from the melt and further annealing above the glass transition temperature over a composition range. The PVDF/PEMA blend with weight ratio of 3:2 has formed higher content of PVDF β crystals than others. By taking advantage of fast cooling rate of ultrafast differential scanning calorimeter (UFDSC), the quenching process of blends was modeled and tested simultaneously, and the melting behavior of β crystals in all blends was investigated. Three types of crystallization behavior of β phase PVDF in blends were found after quenching-annealing at different temperatures.
关键词： PVDF/PEMA blend,Ultra-fast scanning calorimetry,Mesophase,β-Crystal of PVDF
更新于2025-09-10 09:29:36
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Improving the electroactive phase, thermal and dielectric properties of PVDF/graphene oxide composites by using methyl methacrylate-co-glycidyl methacrylate copolymers as compatibilizer
摘要： In this work, graphene oxide sheets (GO) filled polyvinylidene fluoride (PVDF) nanodielectric composites with methyl methacrylate-co-glycidyl methacrylate copolymer (MG) as compatibilizer were fabricated by solution blend process. MG improved the dispersion of GO and enhanced the interface strength between GO and PVDF matrix. The strong dipolar interaction between MG on the surface of GO and PVDF resulted in the crystal transformation of PVDF from a-phase to b/c-phase and nearly 81% b/c-phase PVDF formed for PVDF/MG@GO7.0 composite. The thermal stability, mechanical property, melting and crystallization behaviors of PVDF/MG@GO composites were improved obviously due to the enhanced interface strength between GO and PVDF matrix with the aid of MG. MG copolymers not only contributed to the uniform dispersion of GO in PVDF, but also prevented the direct connection of GO and effectively inhibited the occurrence of leakage current in composites. Therefore, the dielectric properties of PVDF/MG@GO composites were also enhanced significantly with the addition of MG compared with the PVDF/GO composites, which supported the fact that the dielectric properties of resulted composites could be tailored by using MG copolymer as compatibilizer.
关键词： thermal properties,PVDF,graphene oxide,compatibilizer,dielectric properties
更新于2025-09-10 09:29:36