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排序方式: 共有257条查询结果,搜索用时 15 毫秒
1.
Jiajia Suo Bowen Yang Edoardo Mosconi Hyeon-Seo Choi YeonJu Kim Shaik M. Zakeeruddin Filippo De Angelis Michael Grätzel Hui-Seon Kim Anders Hagfeldt 《Advanced functional materials》2021,31(34):2102902
Surface passivation treatment is a widely used strategy to resolve trap-mediated nonradiative recombination toward high-efficiency metal-halide perovskite photovoltaics. However, a lack of passivation with mixture treatment has been investigated, as well as an in-depth understanding of its passivation mechanism. Here, a systematic study on a mixed-salt passivation strategy of formamidinium bromide (FABr) coupled with different F-substituted alkyl lengths of ammonium iodide is demonstrated. It is obtained better device performance with decreasing chain length of the F-substituted alkyl ammonium iodide in the presence of FABr. Moreover, they unraveled a synergistic passivation mechanism of the mixed-salt treatment through surface reconstruction engineering, where FABr dominates the reformation of the perovskite surface via reacting with the excess PbI2. Meanwhile, ammonium iodide passivates the perovskite grain boundaries both on the surface and top perovskite bulk through penetration. This synergistic passivation engineer results in a high-quality perovskite surface with fewer defects and suppressed ion migration, leading to a champion efficiency of 23.5% with mixed-salt treatment. In addition, the introduction of the moisture resisted F-substituted groups presents a more hydrophobic perovskite surface, thus enabling the decorated devices with excellent long-term stability under a high humid atmosphere as well as operational conditions. 相似文献
2.
Major limitation for use of epoxy thermosets in engineering applications is its sudden brittle failure. In the present study dipropylene glycol dibenzoate (DPGDB) based plasticizer is used to modify diglycidyl ether of bisphenol A (DEGEBA) based epoxy resin system via simple blending technique. Bio-based epoxidized linseed oil was also used to modify epoxy resin system and compared with DPGDB modified resin. For DPGDB modified resin storage modulus and loss modulus of the epoxy system modified with 10% plasticizer increased by 7.54% and 12.24%, respectively. The primary mechanism responsible for such behavior is improved crosslinking density. With 5% plasticizer loading, flexural strength increased by 21%. There was an improvement of 312.74% in strain at failure for 10% plasticizer loading, while preserving its mechanical strength. It was found that DPGDB based modification was better than epoxidized linseed oil modification. 相似文献
3.
Rao K. Srinivasa Madhuri T. Krishna Leela Sairam T. Manish Vali Shaik Shoukath Chand Ch. Gopi Sravani K. Girija 《Microsystem Technologies》2022,28(12):2697-2704
Microsystem Technologies - In this paper, we have designed and simulations of RF MEMS shunt switch. The electro-mechanical and electromagnetic analysis of the switch have been done using COMSOL... 相似文献
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Yuanxin Zhou Mohammed A. Baseer Hassan Mahfuz Shaik Jeelani 《Materials Science and Engineering: A》2006,420(1-2):63-71
This paper presents an analytical approach which combines the modified shear-lag model and Monte Carlo simulation technique to simulate the tensile failure process of unidirectional T700 carbon reinforced composite. Two kinds of matrix were investigated in the present paper, one is neat epoxy and the other one is SiC nano-particle filled epoxy. In the model, the strength of the fiber elements is randomly allocated by the Monte Carlo method, the elastic properties of the matrix elements and the friction after the interfaces breakage are definitely allocated. Using this model, the deformation, damage and failure process of the composite are simulated on the microscopic level, the tensile stress–strain relationship is well predicted. The relationship between mechanical properties of the fiber, matrix and composites was discussed. The analysis also shows that, compared with the neat system, nano-phased composite exhibits 10% improvement in tensile strength, which agrees with the experimental data. 相似文献
6.
Shaik Abdul Subhani Karsh Ram Kumar Islam Mohiul Laskar Rabul Hussain 《Multimedia Tools and Applications》2022,81(2):2489-2516
Multimedia Tools and Applications - In the recent digitization era, image hashing is a key technology, including image recognition, authentication and manipulation detection, among many multimedia... 相似文献
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A novel approach for extracting cellulose nanofibers from lignocellulosic biomass by ball milling combined with chemical treatment 下载免费PDF全文
Cellulose nanofibers (CNFs) were isolated from kenaf fibers and wheat straw by formic acid (FA)/acetic acid (AA), peroxyformic acid (PFA)/peroxyacetic acid (PAA), hydrogen peroxide (H2O2) treatment; and subsequently through ball milling treatment. Characterization of extracted cellulose and cellulose nanofibers was carried out through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), and thermogravimetric analysis (TGA). TEM images showed that extracted cellulose nanofibers had diameter in the range of 8–100 nm. FTIR and XRD results implied that hemicellulose and lignin were mostly removed from lignocellulosic biomass with an increase in crystallinity, and isolation of cellulose nanofibers was successful. The TGA results showed that decomposition temperature of cellulose nanofibers increased by about 27°C when compared with that of untreated lignocellulosic biomass. No significant change was observed in the decomposition temperature of bleached celluloses after ball milling. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42990. 相似文献
9.
This article presents the fabrication and characterization of poly dimethylsiloxane/carbon nanofiber (CNF)-based nanocomposites. Although silica and carbon nanoparticles have been traditionally used to reinforce mechanical properties in PDMS matrix nanocomposites, this article focuses on understanding their impacts on electrical and thermal properties. By adjusting both the silica and CNF concentrations, 12 different nanocomposite formulations were studied, and the thermal and electrical properties of these materials were experimentally characterized. The developed nanocomposites were prepared using a solvent-assisted method providing uniform dispersion of the CNFs in the polymer matrix. Scanning electron microscopy was employed to determine the dispersion of the CNFs at different length scales. The thermal properties, such as thermal stability and thermal diffusivity, of the developed nanocomposites were studied using thermogravimetirc and laser flash techniques. Furthermore, the electrical volume conductivity of each type of nanocomposite was tested using the four-probe method to eliminate the effects of contact electrical resistance during measurement. Experimental results showed that both CNFs and silica were able to impact on the overall properties of the synthesized PDMS/CNF nanocomposites. The developed nanocomposites have the potential to be applied to the development of new load sensors in the future. 相似文献
10.
Contact resistance between two dissimilar materials of finite thickness is formulated as two cylinders in contact over an area at their centers. The noncontact gap between the two cylinders is assumed to be filled with a thermally conducting fluid. The lateral surfaces are insulated, while the top and bottom surfaces are kept at constant temperatures. Heat diffusion equations in the cylinders are transformed to two integral equations for the heat flux through the contact and noncontact areas with the interstitial fluid conductance as a parameter. The integral equations are solved numerically. Therefore, no assumption on the heat flux distribution on the contact and noncontact surfaces is made. An expression for the dimensionless overall resistance is developed using the rate of heat transfer through the contact and noncontact areas. The effects of the length of the cylinders and the gap conductance on the overall and contact resistances were evaluated. Radial heat flux and temperature distributions over the contact and noncontact regions were determined. The results are reported in dimensionless form convenient for a parametric study and design analysis. 相似文献