Adsorbed molecular films, referred to as boundary films in tribology, are widely used in various industrial products as a keyway for surface functionalisation, such as lubricity, wettability, and adhesion. Because boundary films are thin nanometre-scale molecular layers and can easily be removed, their formation process cannot be elucidated in detail. In this study, to analyse the growth dynamics of boundary films, the film thickness and molecular orientation of the boundary film of a fatty acid used as an additive in rolling contact as mechanical stimuli were measured in situ. The measurements were performed on simple test lubricants, which were composed of n-hexadecane and stearic acid, at rolling tribological condition between steel and glass (or sapphire) surfaces by ultrathin film interferometry combined with sum-frequency generation spectroscopy according to a unique protocol. The results quantitatively demonstrate shear-induced boundary film formation. The insight gained from these results is anticipated to enable the formulation of high-performance lubricant additives to further reduce friction loss and high-performance glues that can be freely designed for removability.
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http://dx.doi.org/10.1038/s41598-022-07854-5 | DOI Listing |
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January 2025
Department of Physics, Department of Materials Science and Engineering, and Department of Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, 999077, China.
Tin-based halide perovskites represent a highly promising and eco-friendly alternative to lead-based materials with significant potential for optoelectronic applications. However, their advancement is hampered by challenges such as poor film crystallinity and unintended self-doping. Herein, this work reports the fabrication of high-quality CsSnBr perovskite films by plasma-assisted chemical vapor deposition (PACVD), which improves the film quality.
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January 2025
Multifunctional Materials Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India.
The utilization of single crystals is exponentially growing in optoelectronic devices due to their exceptional benefits, including high phase purity and the absence of grain boundaries. However, achieving single crystals with a porous structure poses significant challenges. In this study, we present a method for fabricating porous single crystals (porous-SC) of CsAgBiBr and related halide double perovskites using an infrared-assisted spin coating technique.
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January 2025
Condensed Matter Physics & Nanoscience Research Laboratory, Department of Physics and Material Science, Madan Mohan Malaviya University of Technology, Gorakhpur, 273010, U.P, India.
Nat Commun
January 2025
The Institute of Technological Sciences, Wuhan University, Wuhan, China.
Flexible perovskite solar cells (F-PSCs) are appealing for their flexibility and high power-to-weight ratios. However, the fragile grain boundaries (GBs) in perovskite films can lead to stress and strain cracks under bending conditions, limiting the performance and stability of F-PSCs. Herein, we show that the perovskite film can facilely achieve in situ bifacial capping via introducing 4-(methoxy)benzylamine hydrobromide (MeOBABr) as the precursor additive.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemistry and Center for NanoScience (CeNS), University of Munich (LMU), Butenandtstraße 5-13, Munich 81377, Germany.
Covalent organic frameworks (COFs), crystalline and porous conjugated structures, are of great interest for sustainable energy applications. Organic building blocks in COFs with suitable electronic properties can feature strong optical absorption, whereas the extended crystalline network can establish a band structure enabling long-range coherent transport. This peculiar combination of both molecular and solid-state materials properties makes COFs an interesting platform to study and ultimately utilize photoexcited charge carrier diffusion.
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