Electronic and optical properties of MoS2–WS2 multi-layers: First principles study

MoS2–WS2 thin layers with different deposition sequences and stacking configurations have been studied using first principles full potential linearized augmented plane wave method. The electronic and optical properties of ten atomic layers (in [0 0 0 1] direction) of MoS2–WS2 are reported in the present paper. Ten layers of MoS2–WS2, which are free from quantum size effects, show an indirect band gap which varies between 0.89 and 1.22 eV by engineering of the layering sequence and stacking configuration. Optical properties like absorption coefficients, dielectric tensors and refractive indices of bilayer and multilayer films of MoS2–WS2 are determined and are found to be different from the ten layers of MoS2 and WS2. Changes in the electronic and optical properties of multilayers have been elaborated in terms of interlayer and intralayer S–S distances. A comparison of absorption spectra deduced using the first principles calculations for Si and different combinations of multilayers of MoS2–WS2 show their applicability in optoelectronics and photovoltaic devices.