Photo: Joachim Rode

Doctorate identifies new 2D materials

Physics Materials Data analysis Information technology
DTU’s next Dr. Techn.—Kristian Sommer Thygesen—is in the process of compiling a database of existing and future 2D materials.

Since the one atom thick carbon material—graphene—was discovered 13 years ago, completely new areas of research have thrived. Researchers have discovered—or artificially manufactured—more than 1,000 new materials which are only a single or a very few atoms thick. But with so many completely new materials, who has an overview? A good candidate is Professor Kristian Sommer Thygesen from DTU Physics, who will be defending his doctoral dissertation on 27 October.

The new materials, which are so thin that they are referred to as two-dimensional (2D) materials, range from insulators, semiconductors, metals to superconductors and magnets. So now research is not being conducted into one wonder material, but into more than 1,000 materials of different types—with different applications.

Among other things, Kristian Sommer Thygesen shows in his doctoral dissertation how he and his research team have acquired basic knowledge of a wide range of 2D materials. With the help of quantum mechanical calculations performed on DTU’s supercomputer Niflheim, he and his colleagues at the Center for Nanostructured Graphene have been able to predict a number of the new 2D materials’ properties.

“It’s about understanding how electrons behave in these materials, and what determines their energy levels. This is crucial in determining their applications. The research can reveal whether a material is a potential candidate for photovoltaic cells, catalysis, optical sensors, LED diodes, batteries, and electronic components,” says Kristian Sommer Thygesen.

"The ambition is to have around 1,000 mapped materials in the database before the new year. Of these, only approximately 50 will be among those already known—while the rest will represent entirely new candidates. The database will be free to use. "
Professor Kristian Sommer Thygesen, DTU Physics

He emphasizes, however, that the field is still in its infancy and that it is therefore difficult to point to specific technologies where 2D materials can make the biggest difference.

Considerable challenges still remain, he says, and the calculations are also subject to a degree of uncertainty. However, if we use a computer to map the characteristics and to deselect materials, we can devote more precious laboratory time to the most promising materials.

Photo: Joachim Rode

2D Lego brick
In recent years, research has taken a further twist. By layering different types of 2D materials together it may be possible to create materials with different combined characteristics, thus opening up completely new possibilities. So whereas researchers only a few years ago had one pitch-black Lego brick—graphene—they have now a box containing many more colours and shapes.

“We now have 1,000 Lego bricks, and in principle, we can take any two random bricks and join them together. When we become really good at this, we can start building entirely new materials,” says Kristian Sommer Thygesen.

However, building without instructions is extremely time-consuming, which is precisely why Kristian Sommer Thygesen’s catalogue of 2D materials and their properties has been launched this year in the form of an online database—where researchers from all over the world can learn more about which materials best suit their particular applications.

“The ambition is to have around 1,000 mapped materials in the database before the new year. Of these, only approximately 50 will be among those already known—while the rest will represent entirely new candidates. The database will be free to use. This is the direction in which the field is heading, and I like the idea of openly sharing our data with others in order to improve transparency, reproducibility, and the efficiency of our research.”