researchers at vanderbilt university (nashville, tenn.) and the institute of physics of the chinese academy of sciences in beijing have developed a new process for naturally creating patterned monolayers that open the door for having two functionalities in a single material, according to a report on the vanderbilt website.

illustration of the triangular pattern formed by the two-dimensional material
chalcogenide that allows the creation of dual-function devices.
(yu-yang zhang/chinese academy of sciences)

“in electronics, two dimensional (2d) materials are a hot topic because of their many potential applications,” the article explained. while graphene drew attention for a number of years, some scientists are now turning to chalcogenides, which have varied electrical, optical, and thermal properties, because they naturally form monolayers.

the researchers demonstrated that “monolayers formed by two chalcogenides (platinum-selenium and copper-selenium) naturally combine with nanoscale precision into alternating triangles with different phases: metallic and semiconductor. because each phase has different electrical and chemical properties, two different types of molecules can bond to its surface, allowing it to perform two functions simultaneously.”

this process moves beyond the standard technique of tailoring 2-d materials, which requires doping with impurities on crystalline structures, by enabling scientists to functionalize the two phases of the material independently.

the research was recently published in nature materials. the abstract stated:

“two-dimensional (2d) materials have been studied extensively as monolayers, vertical or lateral heterostructures. to achieve functionalization, monolayers are often patterned using soft lithography and selectively decorated with molecules.

“here we demonstrate the growth of a family of 2d materials that are intrinsically patterned. we demonstrate that a monolayer of ptse₂ can be grown on a pt substrate in the form of a triangular pattern of alternating 1t and 1h phases.

“moreover, we show that, in a monolayer of cuse grown on a cu substrate, strain relaxation leads to periodic patterns of triangular nanopores with uniform size. adsorption of different species at preferred pattern sites is also achieved, demonstrating that these materials can serve as templates for selective self-assembly of molecules or nanoclusters, as well as for the functionalization of the same substrate with two different species.”