Researchers report on the technology of manufacturing nanosheets in one minute

A research group led by Professor Minoru Osada (Hu) and Postdoctoral Researcher Yu Shi (He, He) at the Institute for Future Materials and Systems (IMaSS), Nagoya University in Japan, has developed a new technology for fabricating thin nanosheets. Films of two-dimensional materials a few nanometers thick, in about one minute.

This technology enables high quality, large nanofilms to be formed in a single click without the need for specialized knowledge or technology. Their findings are expected to contribute to the development of the industrial fabrication process for different types of nanoplatelet devices. The study has been published in Applied Materials and ACS Interfaces.

Nanosheets have a thickness measured in nanometers. Nanometers so thin that the leaves cannot be seen from the side with the naked eye. They have potential uses in several different fields, including electronics, catalysis, energy storage, and biomedicine. Those made of graphene and inorganic nanosheets are being tested for use in a range of devices, from solar cells to sensors and batteries, because they have electrical functionality, transparency and heat resistance that differ from those of conventional bulk materials.

However, current techniques used to fabricate these thin films, such as the Langmuir-Blodgett method, require skilled machining and complex conditions. “Using current methods, it takes about an hour to make a single layer,” Osada said. “This creates a major bottleneck in nanosheet fabrication.”

The group aims to develop a new process that can produce high-quality, elegantly textured monolayer films of nanoflakes easily and in a short time. They developed an automated film-forming process that produced nanosheets in about a minute with a simple drop of an aqueous colloidal solution onto a substrate heated on a heating plate using an automated pipette. Then, they followed this up by aspirating the solution and removing the liquid. The result was a finely tiled monolayer film with no gaps between the nanosheets.

“Reducing the surface tension of the colloidal aqueous solution and enhancing convection of the nanosheets suppressed overlapping and gaps between the nanosheets and allowed us to control their alignment,” Osada said. “The layer-by-layer creation of multilayer films controlled by the nanosheet thickness unit was possible by precisely replicating the fabrication process of slabged monolayer films.”

“The newly developed method is expected to become an important technology as an industrial method for thin-film fabrication and a nano-coating method for nanosheets because it is simple, rapid, and requires only a small amount of solutions to manufacture high-quality, large-area film with precisely tiled alignment.”

“This technology is based on simple drop and aspiration operations using an automatic pipette and does not require specialized knowledge or technology. This technology is applicable to nanosheets with different textures and compositions, such as oxides, graphene and boron nitride, and can form films on substrates of various shapes, sizes and materials, making it a technology Very versatile for shaping films,” Osada said.