(549g) Electronic and Optical Properties of Transition Metal Dichalcogenides MX2 (M = Ti, W and X = S, Se)

Transition metal dichalcogenides (TMD) are two-dimensional materials with remarkable structural and electronic properties which make them potential candidates for applications in diverse fields of electronics, optics, energy and catalysis. These properties vary notoriously depending on the number of layers and also the lateral size of such layers leading to unique physical and chemical properties that are affected by the edge structure and atomic defects in small nanostructures as well as quantum confinement effects. Semiconducting TMD, for instance, are of tremendous interest since they have a band gap in the visible frequency range. In addition, this gap is very sensitive to external conditions such as strain, thus, it can be tuned, making TMD suitable for optoelectronic applications. Therefore, gaining a better knowledge of the optical and electronic properties behavior of these materials is of great importance. Here we perform first principles calculations, including density functional theory (DFT) and other ab initio methods, to evaluate optical and electronic properties of TiS₂ and WSe₂.For TiS₂ we study how these properties behave under certain strain applied in-plane or out-of-plane. For WSe₂, we aim to investigate the effect of lateral size and edge structure on the optical and electronic properties of monolayer sheets of WSe₂ using small nano-discs with different diameters.