Density Functional Theory Investigations of Optoelectronic Characteristics of MoS, MoSe, and MoSSe Monolayers

Two-dimensional (2D) layered materials have illustrated prominent interest with various usages in optoelectronics, nanoelectronics, and solar cells. Numerous physical behaviors of 2D materials have been explored for a category of monolayer transition metal dichalcogenides (TMDCs). These involve molybdenum disulfide (MoS₂), molybdenum diselenite (MoSe₂), and MoSSe Janus monolayers that have gained remarkable interest because of their distinguished optoelectronic features. Particularly, the band gap transitions of these TMDC materials undergo from indirect band gap transition to direct one by reducing the dimension from the bulk-counterpart to their MoS₂, MoSe₂, and MoSSe monolayers, respectively. To this end, we conducted a comparative investigation and analysis of the electronic structure behaviors as well as optical spectra of MoS₂, MoSe₂, and MoSSe monolayers. The optical absorption spectra of these 2D materials are ranging between the infrared (IR) and visible regimes for MoS₂, MoSe₂, and MoSSe sheets and the absorption of light emerges between 1.6 and 1.8 eV, corresponding to their semiconducting character. These 2D materials are potential candidates for solar cells and optoelectronic applications.