Electronic and optical properties of Janus PtSSe multi-layers: a DFT study

One way to tune the electronic and optical properties of two-dimensional materials is by controlling the layer thickness. In this study, we investigated the dependence of the electronic and optical properties on the layer thickness of Janus PtSSe, where the number of layers N ranges from one to six. Bilayer PtSSe preserves the semiconductor nature of the monolayer structure but reduces the band gap. Depending on the stacking order and junction of the bilayer, the value of the band gap ranges from 0.369 to 1.146 eV, whereas that of amonolayer is 1.33 eV. Beyond two layers, PtSSe multilayer begin to resemble those of the bulk, where all structures exhibit a semimetallic nature. The optical property calculations show that the bulk structure has the highest maximum absorption of 16.855 x 10(-4) cm(-1), whereas the lowest belongs to the bilayer structure of 3.276 x 10(4) cm(-1). All layers have different absorption regions that fall in infrared, visible, and ultraviolet spectra for different thicknesses. The maximum reflectivity of 93-97% is attained for semimetallic structures of N >= 3, whereas the monolayer and bilayer structures are more transparent. Our results demonstrate the significance of tuning the electronic and optical properties of Janus PtSSe by changing the number of layers, which is necessary for developing different optoelectronic devices.