Transferring graphene from copper foil to a target substrate should ideally be a nondestructive process, but cracks, holes, and wrinkles have proved difficult to prevent. Here we report a method in which we use a commercially available copolymer in addition to poly(methylmethacrylate) (PMMA) to obtain 99.8% continuous centimeter-scale transferred graphene. Our findings are based on characterization using Raman spectroscopy, quantitative image analysis, scanning electron microscopy, and terahertz time-domain spectroscopy. Compared to conventional methods, this copolymer-assisted approach not only results in fewer holes, but also effectively eliminates cracks and wrinkles. We attribute this to a more thorough relaxation of the initially deposited PMMA by solvent contained in the thicker copolymer layer. This results in improved contact at the PMMA-graphene interface before removal of the underlying copper substrate.
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http://dx.doi.org/10.1039/c7ra12328k | DOI Listing |
ACS Nano
December 2024
Department of Chemistry and Center of Super-Diamond & Advanced Films, City University of Hong Kong, Kowloon, Hong Kong 999077, China.
The large-scale preparation of two-dimensional (2D) materials is pivotal in unlocking their extensive potential for next-generation semiconductor device applications. Wafer-scale single crystals of a high-symmetry 2D material (e.g.
View Article and Find Full Text PDFIn this Letter, an all-fiber tunable mode converter for a mini-two-arm Mach-Zehnder interferometer (MTA-MZI) is proposed and realized for the first time to our knowledge. Employing an electric arc discharge technology, we couple a multi-mode fiber (MMF) and a single-mode fiber (SMF), resulting in an MZI characterized by centimeter-scale arms. The varied sensitivity of fiber modes to curvature makes the high-order modes of the MMF more prone to leakage when subjected to bending, leading to alterations in the output interference fringe pattern of the MZI.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
November 2024
Molecular Design and Function Group, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan.
The emergence of macroscopic self-propelled oscillatory motion based on molecular design has attracted continual attention in relation to autonomous systems in living organisms. Herein, a series of perylenediimides (PDIs) with various imide side chains was prepared to explore the impact of molecular design and alignment on the self-propelled motion at the air-water interface. When placed on an aqueous solution containing a reductant, a solid disk of neutral PDI was reduced to form the water-soluble, surface-active PDI dianion species, which induces a surface tension gradient in the vicinity of the disk for self-propelled motion.
View Article and Find Full Text PDFTalanta
October 2024
Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China. Electronic address:
Compact and user-friendly nucleic acid biosensors play a crucial role in advancing infectious disease research, particularly for coronavirus (COVID-19). While nanophotonic metasurface sensors hold promise for high-performance sensing, they face challenges due to their complexity and bulky readout instruments. In this study, we propose a gradient nanoplasmonic imaging (GNI) metasurface that incorporates the concept of an optical potential well, enabling label-free single-step detection of SARS-CoV-2 sequences.
View Article and Find Full Text PDFSmall
November 2024
Center for Photonic Science and Engineering (CPhSE), Skolkovo Institute of Science and Technology, 3 Nobel Street, Moscow, 143026, Russian Federation.
Various polytypes of van der Waals (vdW) materials can be formed by sulfur and tin, which exhibit distinctive and complementary electronic properties. Hence, these materials are attractive candidates for the design of multifunctional devices. This work demonstrates direct selective growth of tin sulfides by laser irradiation.
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