High-Throughput Characterization of Transition Metal Dichalcogenide Alloys: Thermodynamic Stability and Electronic Band Alignment

Alloying offers a way to tune many of the properties of the transition metal dichalcogenide (TMD) monolayers. While these systems in many cases have been thoroughly investigated previously, the fundamental understanding of critical temperatures, phase diagrams, and band edge alignment is still incomplete. Based on first-principles calculations and alloy cluster expansions, we compute the phase diagrams of 72 TMD monolayer alloys and classify the mixing behavior. We show that ordered phases in general are absent at room temperature but that there exist some alloys that have a stable Janus phase at room temperature. Furthermore, for a subset of these alloys, we quantify the band edge bowing and show that the band edge positions for the mixing alloys can be continuously tuned in the range set by the boundary phases.

Automated summary

Alloying can tune the properties of transition metal dichalcogenide (TMD) monolayers. This study investigates the phase diagrams and mixing behavior of 72 TMD monolayer alloys through first-principles calculations and alloy cluster expansions. It is found that ordered phases are generally absent at room temperature, but certain alloys exhibit a stable Janus phase. Additionally, the band edge positions of some alloys can be continuously tuned within the range set by the boundary phases.