Tuning electronic and optical properties of MoS2 monolayer via molecular charge transfer

Abstract

Density functional theory computations were performed to investigate the adsorption of four organic molecules, including tetracyanoquinodimethane (TCNQ), tetracyanoethylene (TCNE), tetrathiafulvalene (TTF) and benzyl viologen (BV) on the basal plane of MoS₂ monolayer (MoS₂ML). There mainly exist non-covalent weak interactions between these organic molecules and MoS₂ML with considerable charge transfer. Due to the adsorption of organic molecules, the band gap of MoS₂ML can be efficiently reduced as the flat molecular levels lie in the band gap region of MoS₂ML. Moreover, the adsorption of TCNQ can significantly enhance the optical absorption of MoS₂ML in the infrared region of solar spectrum, whereas the adsorption of other molecules has negligible effect on the optical properties of MoS₂ML. Our computations provide a flexible approach towards tuning the electronic and optical properties of MoS₂ML.