Transferring the high power conversion efficiencies (PCEs) of spin‐coated perovskite solar cells (PSCs) on the laboratory scale to large‐area photovoltaic modules requires a significant advance in ...scalable fabrication methods. Digital inkjet printing promises scalable, material, and cost‐efficient deposition of perovskite thin films on a wide range of substrates and in arbitrary shapes. In this work, high‐quality inkjet‐printed triple‐cation (methylammonium, formamidinium, and cesium) perovskite layers with exceptional thicknesses of >1 µm are demonstrated, enabling unprecedentedly high PCEs > 21% and stabilized power output efficiencies > 18% for inkjet‐printed PSCs. In‐depth characterization shows that the thick inkjet‐printed perovskite thin films deposited using the process developed herein exhibit a columnar crystal structure, free of horizontal grain boundaries, which extend over the entire thickness. A thin film thickness of around 1.5 µm is determined as optimal for PSC for this process. Up to this layer thickness X‐ray photoemission spectroscopy analysis confirms the expected stoichiometric perovskite composition at the surface and shows strong deviations and inhomogeneities for thicker thin films. The micrometer‐thick perovskite thin films exhibit remarkably long charge carrier lifetimes, highlighting their excellent optoelectronic characteristics. They are particularly promising for next‐generation inkjet‐printed perovskite solar cells, photodetectors, and X‐ray detectors.
This work demonstrates inkjet‐printed triple‐cation perovskite solar cells with high efficiencies of >21% and stabilized power conversion efficiencies up to 18.5%. The printed thin films are micrometer thick and show large columnar grains over the entire layer. Material properties are linked to device performance and a detailed report on the fabrication process is given.
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•Ionic liquid as multifunctional additive regulates electrodeposition, structure and properties of copper foils.•The as-prepared copper foil gives ultrahigh tensile strength and ...elongation.•Refining crystal grains and increasing twin boundaries account for the superior properties of copper foils.
Improving the properties of electrodeposited copper foil, the negative current collector of lithium-ion batteries, is crucial to the ongoing development of high-energy–density batteries. Despite the broad usage of chemical additives to regulate the copper foil, there remains substantial room for advancement due to the complexity of the mixed additives and the lack of related mechanism research. In this study, a functionalized ionic liquid, 1-aminopropyl-3-methyl imidazole chloride (C3NH2CImCl), was designed and used as a new and single additive for controlling the deposition growth of Cu2+ ions, allowing the preparation of copper foil with ultrahigh tensile strength and simultaneously high elongation. By using the optimal C3NH2CImCl concentration of 30 mg/L, copper foil with a tensile strength of 455.6 MPa and an elongation as high as 17.1 % can be achieved. Subsequent structural characterizations and electrochemical analysis suggested that the addition of C3NH2CImCl regulated the grain growth through cathode polarization and enhanced the copper foil properties by refining crystal grains and increasing the density of the Σ3 twin boundaries of the copper foil. A detailed understanding of the mechanism through which C3NH2CImCl affects Cu2+ ions electrodeposition is crucial for the development of innovative additives for electrodeposited copper foils, particularly for the production of high-property copper foils.
The simple planar configuration of organic–inorganic hybrid perovskite solar cells produced by a solution coating process has great potential to be a low-cost and high efficiency photovoltaic ...technology. However planar perovskite films produced by “normal” spin coating usually show a dendritic grain morphology giving many gaps in the film, resulting in poor coverage of the substrate and thus a low power conversion efficiency. Here a facile gas-assisted solution processing technique is reported that has changed the kinetics of nucleation and crystal growth of the perovskite during the spin coating, producing very uniform perovskite thin films consisting of densely packed single crystalline grains. This microstructure is an ideal candidate for the p–i–n solar cell device. Planar perovskite solar cells constructed from these films produced a highly reproducible average power conversion efficiency of 15.7±0.7%. The highest efficiency achieved was 17.0% with a slightly lower steady-state value of 16.5% at the maximum power output of the solar cell.
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•A facile gas-assisted method was employed to prepare uniform CH3NH3PbI3 film.•The gas-assisted method promoted the fast nucleation of CH3NH3PbI3 from DMF solution.•The perovskite film was composed of single-crystal grains with high crystallinity.•Planar perovskite solar cells constructed using these films showed the best efficiency of 17%.•The prepared solar cells had a good reproducibility with an average efficiency of 15.7±0.7%.
Two-Dimensional Compact Variational Mode Decomposition Zosso, Dominique; Dragomiretskiy, Konstantin; Bertozzi, Andrea L. ...
Journal of mathematical imaging and vision,
06/2017, Letnik:
58, Številka:
2
Journal Article
Recenzirano
Decomposing multidimensional signals, such as images, into spatially compact, potentially overlapping modes of essentially wavelike nature makes these components accessible for further downstream ...analysis. This decomposition enables space–frequency analysis, demodulation, estimation of local orientation, edge and corner detection, texture analysis, denoising, inpainting, or curvature estimation. Our model decomposes the input signal into modes with narrow Fourier bandwidth; to cope with sharp region boundaries, incompatible with narrow bandwidth, we introduce binary support functions that act as masks on the narrow-band mode for image recomposition.
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and TV terms promote sparsity and spatial compactness. Constraining the support functions to partitions of the signal domain, we effectively get an image segmentation model based on spectral homogeneity. By coupling several submodes together with a single support function, we are able to decompose an image into several crystal grains. Our efficient algorithm is based on variable splitting and alternate direction optimization; we employ Merriman–Bence–Osher-like threshold dynamics to handle efficiently the motion by mean curvature of the support function boundaries under the sparsity promoting terms. The versatility and effectiveness of our proposed model is demonstrated on a broad variety of example images from different modalities. These demonstrations include the decomposition of images into overlapping modes with smooth or sharp boundaries, segmentation of images of crystal grains, and inpainting of damaged image regions through artifact detection.
Mesoporous LTA zeolite was synthesized by heating only the organic-free mother slurry that runs through a flow-type microwave reactor system within a few minutes. The synthesized LTA particles were ...well-crystallized automorphic crystals with a diameter range of 300–600 nm. Each particle consisted of small crystal-grains, which exhibited a mesoporous feature. The vapor adsorption characteristics confirmed that water adsorption occurs in the mesoporous region in addition to adsorption in the micropores.
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•LTA zeolite was synthesized using the original flow-MW system within a few minutes.•The system enables the precise control of the temperature to obtain a single phase.•Mesoporous LTA was obtained from the viscos mother slurry without additives.•Each mesoporous LTA particle consisted of small crystal-grains.•The vapor adsorption isotherm confirmed the water adsorption in the mesopores.
Dissimilar Ti-based amorphous alloy sheets were butt welded by a pulsed laser and metallurgical joints were obtained. The β-Ti crystal grains in nanometre scale unevenly distribute on the amorphous ...background in the fusion zone. With the increase of laser pulse energy and pulse duration, the crystalline β-Ti grains grow up from spherical to dendritical profile, but the crystalline size reaches its maximum of about 1 µm, which is much smaller than the grains in base metal. The refinement of the grains in fusion zone results from the fast cooling speed during welding. The microhardness in the welded joints ranges from 470 to 525 HV. Average tensile strength of the welded joint is about 1510 MPa (86% of pure Ti-based amorphous alloy BM and 91% of β-Ti dendrite reinforced Ti-based amorphous alloy BM).
The process of electrodeposition of nickel coatings from electrolytes based on a deep eutectic solvent (DES) mixture of choline chloride and lactic acid with a molar ratio of 1:3 was studied. The ...physicochemical properties and characteristics of DES, namely, conductivity, FT-IR and NMR analysis were determined. FT-IR results confirmed that H-bonds occurring between two components in DES were the main force leading to the eutectic formation. Electrochemical techniques were used to characterize the deposition process and scanning electron microscopy was used to study the deposit morphology. Based on polarization measurements, it has been found that at NiCl2·6H2O content of 1.14 M and a temperature of 75 °C, the limiting current density of nickel electrodeposition was near 2 A dm-2. The polarization of the cathodic nickel deposition varied within -0.63 to 1.1 V at current density of 0.25 A dm-2 It has been shown that an increase of water content in the electrolyte does not significantly affect the current efficiency of the nickel electrodeposition process, which was in a range 85-93 %. However, the increase in water content contributes to the increase of heterogeneity and crystal grains size distribution of galvanic deposits. The established values of the Wagner number indicate the predominance of the primary current density distribution in the process of electrodeposition of nickel coatings. Galvanic coatings possess a highly developed nanostructured surface, exhibit increased capillary properties, and can be used as electrode materials for the process of electrolysis of water.
Scuffing is a catastrophic failure that causes significant surface damages such as plastic flow and welding with a marked increase in friction, wear, temperature and noise. In this study, variations ...in the crystal grain structure of a steel surface was analysed in situ during the scuffing process using a synchrotron X-ray diffraction system, combined with a visible camera and a near-infrared thermometer. The in situ observation system was synchronously operated to capture a contact area between a rotating sapphire ring and a stationary bearing steel pin. The Debye–Scherrer ring diffracted from the contact area was captured by a two-dimensional detector. The scuffing behaviour could be classified as either micro scuffing or macro scuffing. During the micro scuffing period, plastic flow occurred intermittently with a significant temperature rise of approximately 1000 °C. During the macro scuffing period, heat was continuously generated over the contact area. When plastic flow occurred, the captured Debye–Scherrer ring indicated the orientation of crystal grains as well as a phase transformation from martensite to austenite. This study constitutes the first in-situ observation of the behaviour of crystal grains in the dynamic recrystallisation process occurring during the scuffing process.
Graphic Abstract
Implantation of heavy ions into metal matrices leads to the creation of a high concentration of radiation defects. X-ray diffraction studies of Mo and Ta foils implanted with
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Fe ions have been ...carried out. It is shown that the implantation of Fe ions does not significantly affect the lattice parameters. It has been established that irradiation leads to the broadening of diffraction lines and a decrease in the size of crystal grains. The Mo and Ta foils are found to be highly textured, with {100} orientation in the foil plane. Irradiation with Fe ions has no noticeable effect on the texture. However, subsequent annealing at a temperature of 700°С weakens the texture on the irradiated side for Mo and Ta foils without affecting the texture of the nonirradiated side.
The size of crystal grains in lead halide perovskite thin films remains a vital design feature for durable optoelectronic devices. With larger crystals and reduced grain boundaries per surface area, ...the stability of the structures improves as degradation, caused by moisture and oxygen percolating into the grain boundaries, is minimized. Thus far, large scale continuous lateral films of methylammonium lead iodide (MAPbI3) with macroscale crystal grains compatible with thin film (<1 μm thick) solar cells and photodetectors have not been reported. Herein, we employ meniscus-guided blade coating technique to grow thin films of highly oriented millimeter-size MAPbI3 crystals, resulting in over an order of magnitude responsivity enhancement over spin-coated films in lateral photoconductors with channel lengths over 100 μm. Furthermore, the blade-coated MAPbI3 thin films exhibit anisotropic higher conductivity along crystal grains over a millimeter range. With crystals orders of magnitude larger in size, and with no additive treatment or additional layers, blade-coated devices manifest improved stability and retain over 80% of their performance tested in ambient air for over 300 h in comparison to spin-coated devices that reach less than 50% of their original peformance within the first 36 h.
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