Investigating the structural, electronic, adsorption and optical properties of Te-doped g-ZnO monolayer before and after adsorbing Hg0 and HgCl2, using DFT plus U, TDDFT and DFT-D2 approaches

The electronic and optical properties of Te doped g-ZnO monolayer before and after adsorbing Hg-0 and HgCl2 have been studied by DFT approach. Given the sign and magnitude of adsorption energies, these adsorptions are possible. According to the band structure of ZnO + Te, ZnO + Te + Hg-0 and ZnO + Te + HgCl2 layers, the gZnO gap changed into semiconductor range. By calculating the absorption spectrum, using the TDDFT, we found that all cases have the similar peaks in the ranges of FUV and EUV. These two adsorptions increase the intensity of peaks. The adsorption of Hg-0 creates a peak in the MUV range. In addition, the ZnO+ Te + Hg-0 has a peak in the visible range. By adsorbing HgCl2, a peak appears in the IR-A range. For the resulting materials, having UV/ Vis/IR peaks makes it possible to use them in photovoltaic devices. After adsorbing HgCl2 and Hg-0 by ZnO + Te monolayer, the step behavior of index of refraction is enhancing.