Two-dimensional (2D) materials comprise a network of atoms bonded in a sheet of only a few atoms thick, and micron-size in-plane dimensions. Of the many 2D materials that have been isolated of synthesized, the transition metal di-chalcogenides, or TMDCs, have attracted special attention. Depending on the specific transition metal involved, TMDCs are metallic, semimetallic, or semiconducting, and an inspiration for a future of 2D electronic devices. Some TMDCs direct semiconductors, which makes them interesting for optoelectronic applications, and, as they also exhibit catalytic activity, for (photo)catalytic applications.
Besides for applications, 2D materials are also interesting for studying fundamental physics, as in reduced dimensions electrons can behave differently. In particular, the interactions among the electrons, or between the electrons and the atomic lattice, becomes more important, leading to phenomena such as spin density waves or charge density waves, in interplay with the electric polarization. In addition, topological electronic effects are more prominent in 2D.
In our group we use electronic structure calculations to study applications, as well as fundamental properties of 2D materials and materials combinations. We suggest solutions for practical problems, such as which material to use to make (Schottky) barrier-less contacts to TMDCs, and explore fundamental problems, such as the emergence of spin-density waves at TMDC heterojunctions, see the figure below. We look into the catalytic activity of 2D materials for water splitting, which is required for producing hydrogen as a future energy carrier, and also study how 2D materials can be combined with perovskites in future solar cells.