Analysis of the Electronic and Optical Properties of MoS2 and WSe2 Using the First-Principle Density Functional Theory

This paper describes the two-dimensional materials that are popular for their unique properties. The first is the introduction of transition metal dichalcogenides (TMDs) molybdenum disulfide (MoS2) and tungsten selenide (WSe2). Potential replacements for the traditional semiconductor materials used in the IC industry include MoS2 and WSe2 due to their unique properties including electronic and optoelectronic. Simulations were done by using Quantum Espresso for the electronic properties of MoS2 and WSe2.The potential bandgap-tuning of MoS2 and WSe2 has generated interest. The thickness of the material depends on the transition between the direct and indirect bandgap. To examine the features of the MoS2 and WSe2, density functional theory (DFT) is used for first-principle computations on electronic structures. The direct band gap is at K, and the indirect band gap of MoS2 and WSe2 is between the point of the first Brillouin zone and Γ and Γ-K. ‘DFT material properties simulator’ is used to investigate the optoelectronic properties for finding parameters such as absorption coefficient, extinction coefficient, and refractive index for the comparative analysis of mono- and bulk-layer MoS2 by logarithmic graph scale. Our results show the analysis of the electronic properties of MoS2 and WSe2, where MoS2 has better electronic properties than WSe2 with SCF total energy value of MoS2 (−993.3918 Ry) which is better than WSe2 (−402.008Ry), and it will take lesser time for SCF to converge. Overall, calculating SCF and DOS are important steps in the first-principle DFT approach and provide valuable information about electronic properties. After that, we calculated the optoelectronic properties of its mono-layer and bulk-layer and their comparative analysis. The comparative analysis of bulk and mono-layer MoS2 can be used to find visible light (light of wavelength below 500 nm) that can be used as a photodetector. Also, it has been found that MoS2 is most sensitive to light with a wavelength of 450 nm. MoS2 and WSe2 distinct bandgap characteristics can improve their applicability in energy devices like solar cells, FETs, and transistors, double gate FETs in pH sensors, optoelectronics, spintronics, and photoluminescence.