Technique To Synthesize Monolayer Films

Technique To Synthesize Monolayer Films - Featured Graphene Other 2D materials
Figure: (Top) Photos showing spin-coating settings used to coat a substrate surface with a colloidal suspension of titanium oxide nanosheets. (Bottom) Schematic diagram illustrating the mechanism of synthesizing a monolayer film composed of neatly tiled nanosheets. A thin layer of the suspension is first formed over the substrate surface. The thickness of the layer is then gradually reduced, which causes its interference colors to change. The layer eventually dries. Credit: National Institute for Materials Science

A NIMS group has developed a novel technique to synthesize monolayer composed of neatly tiled two-dimensional materials, such as oxide nanosheets and , on substrate surfaces in as quickly as one minute.

A NIMS research group led by Takayoshi Sasaki has developed a novel technique to synthesize monolayer films composed of neatly tiled two-dimensional , such as oxide nanosheets and graphene, on surfaces in approximately one minute. The technique may facilitate industrial production of various nanosheet-based devices as it offers a simpler and quicker alternative to the conventional, complicated film fabrication procedures.

Ultimate two-dimensional materials of atomic- or molecular-scale thickness—represented by graphene and oxide nanosheets—possess a number of extremely desirable properties (e.g., high conductivity, high dielectric and catalytic properties). For this reason, their potential to bring about technological innovation in a wide range of fields, including , environmental and technology has been much anticipated, making them the subject of active R&D efforts worldwide. Many two-dimensional materials have been produced in colloidal form (i.e., sheet materials with widths within the micrometer range dispersed in solutions). In order to take full advantage of the properties of these materials for device applications, an important first step is to array them in an orderly manner—like playing cards—on the surfaces of various base materials. In other words, it is critical to develop a technique to eliminate gaps and overlapping between nanosheets arrayed in monolayer films. Once a monolayer film can be successfully synthesized, it will be feasible to synthesize multilayer films and superlattice films by repeating the monolayer film synthesis process. This approach could potentially lead to the development of devices with diverse functions. Currently, the Langmuir-Blodgett (LB) method is generally used to synthesize monolayers composed of neatly tiled nanosheets. However, this method is not practical for industrial-scale production as it requires skillful manipulation and complex conditions. In addition, the fabrication of films using this method normally takes about one hour. Because of these issues, there is strong demand for the development of simpler, quicker and more industrially practical film fabrication techniques.

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