The ICMM improves its technique for manufacturing cheap electronic devices with two-dimensional materials

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Ultra-thin materials, just two dimensions thick, are the key to today's electronics and, consequently, to those of the future. However, obtaining them is often an expensive or low-yield task. Now, an international effort led by a team from the Madrid Institute of Materials Science (ICMM-CSIC) has improved its own mechanical exfoliation technique to create and scale up the production of this class of materials in a cheap, scalable way, and with higher performance than similar technologies.

The key findings of the work have just been published in the journal Nano Materials Science. This represents a significant evolution of a previous study in which this team developed a roller system to carry out mechanical exfoliation of the material. To understand the significance of this, Andrés Castellanos Gómez, a CSIC researcher at the ICMM-CSIC and leader of the work, explains that two-dimensional materials (known as van der Waals materials, such as graphite) are typically obtained either by printing techniques (cheap but with very low performance) or by chemical deposition/evaporation (better performance, but very expensive). Mechanical exfoliation would fall between these two techniques, usually relying on adhesive tape applied to the material to be exfoliated and then peeling it off to obtain the two-dimensional layers.

The ICMM technique is a substantial improvement over this conventional manual mechanical exfoliation. "We aim to fill the gap between the two techniques, with material films that are cheaper than printed ones but with performance similar to that achieved by chemical evaporation," explains Castellanos-Gómez. In 2023, their technique consisted of a roller system with counter-rotating cylinders: the rollers were covered with adhesive tape, and the material to be exfoliated was placed on them. In this way, when both cylinders were rotated, they made contact, replicating on a larger scale the sticking-and-peeling process carried out in manual mechanical exfoliation. "At the end of the process, the adhesive tape is completely covered with graphene, molybdenum disulfide, or any other layered material (in two dimensions)," Carmen Munuera, also a researcher at the ICMM-CSIC and a member of the team, explained at the time.

Now, a horizontal sliding motion of the rollers has been incorporated into this system, which has made the films of these nanosheets uniform and increased their size. "We achieve wafer-scale films, that is, about five centimeters in diameter—a size used in industry," the team explains. The result of the improvement has been confirmed by examining the electronic properties of the material: "This scalable technique enables the fabrication of high-quality films suitable for electronic and optoelectronic applications," celebrates Castellanos-Gómez.

To verify that the process works, the team has fabricated phototransistors from a semiconductor called tungsten diselenide (WSe2), achieving performance parameters "comparable to the best devices reported based on electrochemically exfoliated material." "The dry transfer method used ensures minimal contamination and preserves the intrinsic properties of the material," continues Munuera, who highlights that this work "underscores the potential of high-throughput mechanical exfoliation as a cost-effective and reliable route for large-scale production of devices based on 2D materials."

This work has been made possible thanks to funding from the Spanish Ministry of Science, Innovation and Universities, through the Severo Ochoa excellence program and other national projects, as well as from the European Research Council.
 

Reference:
Yigit Sozen* Thomas Pucher, Bhagyanath Paliyottil Kesavan, Nuria Jiménez-Arévalo, Julia Hernandez-Ruiz, Zdenek Sofer, Carmen Munuera, Juan J. Riquelme, Andres Castellanos-Gomez *. Wafer-scale films of two-dimensional materials via roll-to-roll mechanical exfoliation. Nano Materials Science. DOI: https://doi.org/10.1016/j.nanoms.2026.03.018