A Comparative DFT Study of Bandgap Engineering and Tuning of Structural, Electronic, and Optical Properties of 2D WS 2 , PtS 2 , and MoS 2 between WSe 2 , PtSe 2 , and MoSe 2 Materials for Photocatalytic and Solar Cell Applications

In early twenty-first century, 2D materials are among the most systematically reachable in the field of material science. Due to its semiconductor properties, the transition metal dichalcogenide family has received attention. In the current research, the GGA-PBE simulation approximation is used to tune energy bandgap (E g ), optical and electronic properties of TMDCs (transition metal dichalcogenide) such as WS 2 , PtS 2 , MoS 2 , WSe 2 , PtSe 2 , and MoSe 2 by density functional quantum computing simulation. It is calculated that the energy bandgap (E g ) of WSe 2 , PtSe 2 , and MoSe 2 shows a decrement trend with small E g 1.43, 0.88, and 0.74 eV respectively as compared to WS 2 , PtS 2 , and MoS 2 with large E g 1.96, 1.62, and 1.50 eV respectively with direct to indirect semiconductor nature. In WSe 2 , PtSe 2 , and MoSe 2 materials the extra gamma active states created which help to build the conduction and valance bands as a consequence of decrement in the E g . A detailed study of optical conductivity shows that optical conductance increases with bandgap decrement (1.96–0.74 eV) in ultraviolet pattern with small shifts at larger energy bands. 2D-TMDCs MoS 2 and MoSe 2 shows maximum optical conductivity and absorbance 105 × 10 3 Ω −1 cm −1 , 2.78 × 10 5 cm −1 and 85 × 10 3 Ω −1 cm −1 , 3.1 × 10 5 cm −1 respectively as compared to WS 2 , PtS 2 , WSe 2 and PtSe 2 due to small energy bandgap. In the reflectivity, a significant increment is found in MoS 2 and MoSe 2 semiconductor materials as compared to WS 2 , PtS 2 , WSe 2, and PtSe 2 due to the decrement in the bandgap. The family of TMDCs such as WS 2 , PtS 2 , MoS 2 , WSe 2 , PtSe 2 , and MoSe 2 are a capable semiconductors materials has a enhanced surface area for absorbance of photo-generated charge carriers and decrease the photo-generated charge carriers recombination rate and increment the charge transportation. The optical properties significantly enlarged MoS 2 and MoSe 2 materials have proficient energy absorbance, and refractive index as compared to WS 2 , PtS 2 , WSe 2 , and PtSe 2 semiconductors, and all these materials are appropriate for photocatalytic and solar cell applications.