Tunable photoelectric properties of monolayer Mo1−xWxTe2 alloys: a first-principles study

Abstract

Monolayer MoTe₂ and WTe₂ within the two-dimensional transition metal dichalcogenides (TMDCs) material family exhibit broad potential for application in optoelectronic devices owing to their direct band gap characteristics. In this work, upon alloying these materials into a monolayer system denoted as Mo_1−xW_xTe₂, intriguing alterations are observed in the electronic and optoelectronic properties. The photoelectric attributes of these alloys can be tailored by manipulating the respective ratios of molybdenum to tungsten (Mo/W). This investigation employs first-principles calculations based on density functional theory (DFT) to assess physical traits of two-dimensional monolayered structures composed from varying compositions of Mo_1−xW_xTe₂. Our findings reveal that while maintaining a direct band gap characteristic across all compositions studied, there is also a reduction observed in electron effective mass near the Fermi level. Moreover, changing in the Mo/W ratio allows gradual adjustments in electronic properties such as density of states (DOS), work function, dielectric function, absorptivity, and reflectivity. Phonon dispersion curves further demonstrate the stability of Mo_1−xW_xTe₂ systems. Notably, Mo_0.5W_0.5Te₂ exhibits lower polarizability and reduced band gap when compared against MoTe₂ and WTe₂ counterparts. This research underscores how alloying processes enable customizable modifications in the electronic and optoelectronic properties of Mo_1−xW_xTe₂ monolayer materials which is essential for enhancing nanoscale electronic and optoelectronic device design.