Promising optoelectronic response of 2D monolayer MoS2: A first principles study

First, we have considered the two structures of MoS2: one with the hole as no atom is present in the center of the hexagonal cage termed as 1H-MoS2 and the second one with the presence of an atom at the center of the hexagonal cage is 1T-MoS2. We started the calculation employing generalized gradient approximation (GGA) and modified Becke Johnson (mBJ) within a framework of density functional theory (DFT). Interestingly, both GGA and mBJ have given the same low value of band gaps. Therefore, further calculation has been proceeded with the computationally more expensive hybrid functionals like Heyd-Scuseria-Ernzerhof (HSE) and Becke-Lee-Yang-Par (BLYP) within the LCAO-DFT approach. The calculated value of band gap from HSE is found to be 2.35 eV, compared with the previously reported band gap from GW method. However, the direct band gap calculated by BLYP method is 1.83 eV which is consistent with some of the experimental results. The presence of the direct band gap along K - K symmetry in UV–vis range predicts that 1H-MoS2 is a potential candidate for the optoelectronic applications.