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Japanese researchers have developed a kind of nano cellulose paper semiconductor, which shows the nano micron macro cross scale designability of 3D structure and wide adjustability of electrical properties. The results were published in ACS Nano, a core journal of the American Chemical Society.

Semiconductor nanomaterials with 3D network structure have high surface area and a large number of pores, which make them very suitable for applications involving adsorption, separation and sensing. However, it is still challenging to simultaneously control electrical characteristics, create useful micro and macro structures, and achieve outstanding functionality and end use versatility.

Cellulose is a natural and easily available material derived from wood. Nanocellulose (A4) can be made into nanocellulose (nano cellulose) sheets of similar size. Nanopaper is not conductive, but heating can introduce conductive properties. However, this heat can also damage nanostructures.

Osaka University researchers, in collaboration with the University of Tokyo, Kyushu University and Okayama University, have designed a process that allows nanopaper to be heated without damaging the paper structure from the nanoscale to the macroscopic scale.

"An important feature of nanopaper semiconductors is tunability, as it allows design for specific applications." Associate Professor Gu He Bolong, the author of the study, explained that iodine treatment was very effective in protecting the nanostructure of nanopaper. The combination of this with space controlled drying means that pyrolysis does not significantly change the structure of the design, and the selected temperature can be used to control electrical properties.

The researchers used origami and paper cutting techniques to provide nano paper with macro level flexibility. They fold birds and boxes, punch them into shapes like apples and snowflakes, and use laser cutting to create more complex structures. This demonstrates the level of detail that the new process is likely to achieve and that the heat treatment does not cause damage.

For example, nanopaper semiconductor sensors are incorporated into wearable devices to detect moisture exhaled through masks and moisture on the skin. Nanopaper semiconductors are also used as electrodes in glucose biofuel cells, producing energy that lights a small bulb.

Guhebolon said that the structural maintenance and adjustability of the new research to transform nanomaterials into practical devices are very encouraging, and the new methods lay the foundation for the next step in the development of sustainable electronic products made entirely of plant materials.