Toward a Comprehensive Understanding of Oxygen on MoS2: From Reaction to Optical Properties
Wang, Kangli and Paulus, Beate – 2021
Oxygen (O2) has been reported to greatly enhance the photoluminescence (PL) intensity of MoS2 experimentally. However, the corresponding mechanism and atomic configuration are still controversial. Herein, a comprehensive understanding of O2 on MoS2 from the reaction, electronic properties to optical properties, is provided by performing the state-of-the-art GW-Bethe–Salpeter-equation calculation. Our results reveal that the chemisorption and dissociation of O2 on the defective site tend to passivate the defect state and restore the defect-free band structure and optical absorption spectrum of MoS2 due to the isovalence between O2– (or O22–) and S2– when they are bonded with Mo4+. Moreover, the physisorption of O2 on both defective and pristine surfaces could enhance the optical absorption peak which arises from the charge transfer from the underlying MoS2 to the adsorbate. Our work emphasizes the different roles of different adsorption modes of O2 in modulating the electronic and optical properties of MoS2.