Researchers at the Institute of Materials Science in Madrid (ICMM-CSIC) have developed a novel mechanical exfoliation technique to obtain more and better nanosheets van der Waals materials (those that have a layered structure, such as graphene) are much cheaper. The results of the work have just been published in the journal Small methods.
To date, mechanical exfoliation to obtain panels from these materials consists of the use of a Scotch tape on the material you want to peel. When the tape is separated from the material, tiny layers are adhered to it that have the specific properties desired for that particular material.
Although this method is inexpensive and produces high-quality flakes, it is not as scalable as others. To solve this problem is a system of Rollers with polymer cylinders (polyoxymethylene), which rotate facing each other.
The rolls are covered with adhesive tape and the material to be peeled is placed on top. When both cylinders are rotated, they touch each other as they rotate, reproducing on a larger scale the adhesion/detachment process that occurs in manual mechanical peeling.
“At the end of the process, the tape is completely covered with graphene, molybdenum disulfide or another layered material,” he explains. Carmen MunueraResearcher at ICMM-CSIC and one of the authors of the work.
To prevent the rollers from always touching at the same point, it was decided to make them with diameters corresponding to large primes, which ensures “many revolutions are required before the cylinders return to their original relative alignment,” he emphasizes Andres Castellanos-Gómez, also a scientist at ICMM-CSIC and lead author of the study. This ensures that the material is evenly distributed on the adhesive tape.
At the end of the process, the tape is completely covered with graphene, molybdenum disulfide or another layered material.
In this way, they have developed a device that is not only versatile since it can be used with different two-dimensional materials, but also achieves an optimal result (the sheets have a high aspect ratio by obtaining a good lateral size) and an optimal transfer The material is simple. .
“With our method we have a remarkable balance between costs, Scalability and performance“, emphasizes Munuera, pointing out that the technology does not require solvents and therefore leaves no residue between the sheets, “which would have a negative impact on factors such as conductivity.”
The equipment is quite small, which allows working in small spaces, which is necessary when working with materials that decompose in environmental conditions. On the other hand, researchers They shared the plans for their invention in the study itself so that any other laboratory can reproduce it and work with it.
“This method offers opportunities for automation that could increase its commercial use,” adds Munuera. “It is an attractive option for applications in electronics and optoelectronics, as well as for the production of sensors and low-cost electronic components for flexible devices,” concludes Castellanos-Gómez.
Reference:
A. Castellanos-Gomez et al. “High-throughput mechanical exfoliation for cost-effective production of van der Waals nanosheets,” Small methods