Effects of multilayer stacking on the physical properties of 2D CdS using the DFT method

Abstract

In this paper, we have implemented a DFT based Wien2k code to investigate the optoelectronic properties of different CdS multilayers ranging from 1 to 6 stacked layers. The structural properties of CdS multilayers optimized using the GGA-PBEsol approximation show that the different stacked layers are mechanically stable. The optoelectronic properties of CdS multilayers require calculations by the TB-mBJ approach to obtain satisfactory results. Our computational results obtained for the energy band structures show that the gap energy of the first three stacked layers exhibits large gap energy in comparison with the bulk and decreases as well as the stacked layers number increases. Reflectivity and absorption coefficient increase as the number of stacked layers increases, while transmittance decreases. We also note that the first three stacked layers have higher transmittance in the visible range than the bulk. This work proves that nanostructuring by a gradual transition from 3D to 2D structures offers a marked improvement in optoelectronic properties and provides a way to tune the physical properties of the CdS multilayer structure by varying the number of stacked layers. Thus, stacked layers could provide promising efficiency when used as a buffer layer for heterojunction solar cells.