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MAPbI3/agarose photoactive composite for highly stable unencapsulated perovskite solar cells in humid environment
摘要： Perovskite solar cells, bearing the merits of facile preparaion and remarkable efficiency, has great potential for bringing the photovoltaic industry to a new generation. The photovoltaic market demands high-efficiency, high stability and low-cost fabrication of perovksite solar cells, especially stability to the humid environment for operation. Here, MAPbI3/agarose photoactive material for humid stable unencapsulated devices has been proposed. These solar cells have been operated in ambient humid environment without glove box, exhibiting efficiency up to 14.66% and retain 90% of its PCE after 1392 h and 60% of initial PCE after 1972 h in ambient humid environment (RH>70%) without encapsulation. FTIR and XPS measurements reveal two critical factors for the improved stability. The molecular level interactions between agarose and MAPbI3 passivates the grain boundaries of perovskite thus preventing its degradation. Moreover, the formation of Li+-agarose complex at the interface between perovskite layer and hole conductive layer, effectively prevents the water uptake of MAPbI3 layer. Both effects of passivation and minimization of hygroscopicity of LiTFSI by agarose lower the decomposition speed of perovskite, which obviously increases the power efficiency and stability of device.
关键词： humid stability mechanism,perovskite solar cells,MAPbI3/agarose photoactive composite
更新于2025-11-14 15:24:45
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Enhanced visible-light-driven photocatalytic activity of BiFeO3 via electric-field control of spontaneous polarization
摘要： Well-polarized BiFeO3 nanoparticles have been successfully prepared by a facile electrical poling method with the assist of a soluble organic-inorganic composite film. From XRD, TEM and SEM studies, no significant change in the crystal structure or morphology was detected after the electrical poling process. The visible-light driven photocatalytic process of poled BiFeO3 nanoparticles was accelerated by 2 times compared to unpoled BiFeO3. By combining time-resolved photoluminescence (PL), photoinduced silver deposition testing and photoelectrochemical measurements, it can be revealed that the enhanced photocatalytic performance of poled samples can be properly attributed to the promoted separation and prolonged lifetime of the photogenerated carriers caused by the ferroelectric polarization. These findings may offer a new route to promote the photocatalytic or photoelectric performances of BiFeO3 for advanced applications by adjusting the ferroelectric polarization.
关键词： BiFeO3 nanoparticles,Organic-inorganic composite film,Ferroelectric polarization,Electrical poling technology,Photocatalytic activity
更新于2025-11-14 15:24:45
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Obtainment of Stabilized Zirconium Dioxide via the High-Frequency Magnetron Sputtering of a Metallic Target
摘要： The influence of the yttrium concentration on the structure of coatings prepared via the high-frequency magnetron sputtering of a metal target is investigated. The results of coating deposition in pure argon and a mixed (Ar + O2), reactive medium are discussed. It is demonstrated that a nonequilibrium body-centered-cubic solid solution based on zirconium with an extended homogeneous region (up to 16 at % Y) is formed under the condition that a target is sputtered in pure argon. During reactive-coating deposition, the formation of cubic or tetragonal zirconium dioxide is generated depending on the yttrium concentration. The tetragonal structure is created if the yttrium concentration is 8 at %. It is found that the obtained tetragonal zirconium dioxide is thermally stable both in terms of structure and in morphology upon heat treatment in air at 1100°C for 11 h.
关键词： zirconium dioxide,magnetron sputtering,nanostructured film,composite,coating
更新于2025-11-14 15:13:28
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Percolation Effects in Electrolytically-Gated WS <sub/>2</sub> /Graphene Nano:Nano Composites
摘要： Mixed networks of conducting and non-conducting nanoparticles show promise in a range of applications where fast charge transport is important. While the dependence of network conductivity on the conductive mass fraction (Mf) is well understood, little is known about the Mf-dependence of mobility and carrier density. This is particularly important as the addition of graphene might lead to increases in the mobility of semiconducting nanosheet-network transistors. Here, we use electrolytic gating to investigate the transport properties of spray-coated composite networks of graphene and WS2 nanosheets. As the graphene Mf is increased, we find both conductivity and carrier density to increase in line with percolation theory with percolation thresholds (~8 vol%) and exponents (~2.5) consistent with previous reporting. Perhaps surprisingly, we find the mobility increases modestly from ~0.1 cm2/Vs (for a WS2 network) to ~0.3 cm2/Vs (for a graphene network) which we attribute to the similarity between WS2-WS2 and graphene-graphene junction resistances. In addition, we find both the transistor on- and off-currents to scale with Mf according to percolation theory, changing sharply at the percolation threshold. Through fitting, we show that only the current in the WS2 network changes significantly upon gating. As a result, the on-off ratio falls sharply at the percolation threshold from ~104 to ~2 at higher Mf. Reflecting on these results, we conclude that the addition of graphene to a semiconducting network is not a viable strategy to improve transistor performance as it reduces the on:off ratio far more than it improves the mobility.
关键词： graphene,ionic liquid,thin film transistor,WS2,carrier density,composite,mobility,Printed electronics
更新于2025-10-22 19:40:53
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Layer-by-layer MoS2:GO composite thin films for optoelectronics device applications
摘要： With reference of our previous report (Appl. Surf. Sci. 2018, ASAP), the molybdenum disulphide (MoS2) thin film were prepared by the dip-coating technique at different temperatures (4000C – 4500C) using methanolic solution of ammonium molybdate and ammonium thiocyanate that are used as bare-substrate for the deposition of graphene oxide (GO) thin films. For the deposition of graphene oxide (GO), commercially purchased GO (0.5 mg in 10 mL aqueous solution) was deposited by dip-coating technique on dip-deposited MoS2 thin film to make layer-by-layer MoS2:GO composite thin films and hence studied their electronic and electrical behaviours. The micro-structural and surface morphology were studied using Raman spectroscopy and field emission scanning electron microscopy, whereas optical band estimated from the optical absorption spectra. The electronic structure and their bonding properties were studied using x-ray photoelectron spectroscopy and the electrical behaviours were observed from the current-voltage (I-V) characteristic curve. The formation of different phases of MoS:GO thin films show an enhanced electronic and electrical performance due to their unique-structure and the synergetic effect of MoS2:GO nanosheets when compared to those of bare MoS2.
关键词： XPS Spectroscopy,Layer-by-layer MoS2:GO composite thin films,I-V curve
更新于2025-10-22 19:40:53
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Enhanced optoelectronic performance of plasma electrolytic oxidized monocrystalline silicon using rGO incorporation
摘要： rGO/SiO2 composite coating was successfully prepared by plasma electrolyte oxidation (PEO) process on monocrystalline silicon (mc-Si) substrate. Investigating the effect of rGO incorporation into the SiO2 coating revealed that the addition of rGO leads to a significant increase in the photo-trapping ability due to the high specific surface area and excellent electron transfer efficiency. The PL intensity of the composite sample was found to decrease, which signified the suspension of the electron-hole pairs’ recombination. As a result, the photocurrent gain of the composite coating enhanced about 5.5 times. Likewise, the time-response switching featured an over two-fold increase for the rGO/SiO2 coating, impressively.
关键词： Semiconductors,Plasma electrolyte oxidation,Optoelectrical properties,Composite materials,rGO/SiO2 composite
更新于2025-09-23 15:23:52
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Versatile Processing of Metal-Organic Framework-Fluoropolymer Composite Inks with Chemical Resistance and Sensor Applications
摘要： We report a new class of MOF inks with a water-repellent, photocurable fluoropolymer (PFPE) having up to 90 wt% MOF loading. These MOF inks enable to process various MOFs through spray coating, pen writing, stencil printing, and moulding at room temperature. Upon UV-curing, the hydrophobic PFPE matrix efficiently blocks water permeation but allows accessibility of chemicals into MOF pores, thereby freeing the MOF to perform its unique function. Moreover, by introducing functional MOFs we successfully demonstrated a water-tolerant chemosensor for a class of aromatic pollutants in water and a chemical-resistant thermosensor for visualizing temperature image. This approach would open up innumerable opportunities for those MOFs that are otherwise dormant.
关键词： MOF-polymer composite,Chemosensor,MOF processing,Thermosensor,Metal-Organic Framework,Chemical resistance
更新于2025-09-23 15:23:52
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Complex Dielectric and Impedance Spectroscopic Studies in a Multiferroic Composite of Bi2Fe4O9-BiFeO3
摘要： Complex dielectric and impedance spectroscopic studies have been carried out in a detailed manner on the system comprising of Bi2Fe4O9-BiFeO3 composite particles dispersed in a α-Fe2O3 matrix as prepared using ball milling and controlled annealing treatments. This multiferroic composite is observed to exhibit a giant dielectric constant associated with a low tangent loss. A non-Debye type of relaxation has been deduced based on complex modulus analysis. Based on these studies, the important role played by bismuth ferrite nanoshell in the core-shell composite of Bi2Fe4O9-BiFeO3 is elucidated for the observed complex impedance spectroscopic properties of the system. Electron hopping across Fe2+/Fe3+ and oxygen vacancies are deduced to be playing an important role in conduction mechanisms based on activation energy analysis of the complex impedance spectroscopy results.
关键词： dielectric,composite,Bi2Fe4O9,multiferroic
更新于2025-09-23 15:23:52
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PVDF composites with spherical polymer-derived SiCN ceramic particles have significantly enhanced low-frequency dielectric constants
摘要： We report a novel functional hybrid film fabricated by using polysilazane-derived SiCN ceramics as fillers and polyvinylidene fluoride (PVDF) as the matrix. Regular spherical-shaped and amorphous SiCN ceramic powders were fabricated via a facile solvothermal method combined with a polymer-derived ceramic (PDC) process. The dielectric properties of the SiCN/PVDF composites were investigated by broadband dielectric spectroscopy from 0.1 Hz to 106 Hz. The composites showed significantly enhanced low-frequency dielectric constants. When the SiCN loading content reached 40 vol%, the dielectric constant of the composites was approximately 360 at 0.1 Hz, which is 20 times the value of pure PVDF (18). The dielectric constant of the composites at 0.1 Hz fit the effective medium theory (EMT) model well. The results suggest that the SiCN/PVDF composites are promising dielectric materials and have potential use in electrical applications.
关键词： spherical SiCN ceramics,SiCN/PVDF composite,high-e
更新于2025-09-23 15:23:52
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Cs/MAPbI3 composite formation and its influence on optical properties
摘要： The stability issue is very critical for organic hybrid perovskite CH3NH3PbI3 to be used in solar cell applications; whereas CsPbI3 is reported to be more stable than that of CH3NH3PbI3. In the present work, we attempt to substitute Cs+ in the organic hybrid perovskite CH3NH3PbI3 matrix to form Csx(CH3NH3)1-xPbI3 with 0 ≤ x ≤ 0.4 in ambient conditions i.e., at room temperature and in air via solid state reaction route. The structural studies reveal presence of both CH3NH3PbI3 (tetragonal, I4/mcm) and CsPbI3 (orthorhombic, Pnma) phases for x > 0. It is appearing that partial solid solution formation has occurred up to x = 0.2 but for x > 0.2, the composite formation dominates. The optical band gap is slightly increased by ~ 0.02 eV with substitution. These compounds keep the basic feature of parent CH3NH3PbI3 along with stability of CsPbI3.
关键词： Composite,Raman,Perovskite materials,XRD
更新于2025-09-23 15:23:52