Utilization of monolayer MoS2 in Bragg stacks and metamaterial structures as broadband absorbers

• Bragg stacks of monolayer MoS2/thin SiO2 films are studied.
• These stacks can be engineered as almost perfect broadband absorbers or reflectors.
• Purely excitonic Bragg absorbers’ average efficiency can be as high as ~95 %.
• Thin TMD films can enhance the metamaterial absorbers’ efficiency and bandwidth.
• They can be engineered as reflectors for saturable absorption applications.

We numerically study the possibility of using atomically thin transition metal dichalcogenides (TMDs) for applications requiring broadband absorption in the visible range of the electromagnetic spectrum. We demonstrate that when monolayer TMDs are positioned into a finite-period of multilayer Bragg stack geometry, they make broadband, wide-angle, almost polarization-independent absorbers. In our study, we consider molybdenum disulfide (MoS2) and silicon dioxide (SiO2) as semiconducting and dielectric thin film of alternate high- and low- index films, respectively. By optimizing the thickness of the SiO2 film, we find that monolayer MoS2 based Bragg stacks can absorb 94.7% of the incident energy in the visible (350–700 nm). Similar structures can be engineered to make perfect reflectors for saturable absorption applications. We also demonstrate that bandwidth of metamaterial absorbers can be expanded using monolayer TMDs.