First Principles Study On The Electronic And Optical Properties Of Doped Tungsten Disulfide

Tungsten disulfide?WS₂?is one of the transition metal chalcogenides,which has a two-dimensional layered structure of graphene.Single-layer WS₂ is a direct band gap structure,which has similar proximity to the band gap of silicon dioxide,a high specific surface area,a high mobility and so on.The unique electrical,optical and magnetic properties of WS₂ make it widely used in optoelectronic fields such as electronics,sensors and detectors.It has also become one of the hot research materials in recent years.Crystal doping is an effective way to improve the material properties,this improvement can make materials more widely application.Based on the above background,this paper hopes to improve the performance of the material by modulating the electrical and optical properties of WS₂ by element doping.Firstly,the properties,application and research of tungsten disulfide were introduced.The purpose and significance of this paper were expounded.The basic theories and methods involved in this paper were summarized.Then,a pure tungsten disulfide model and the?A group elements O,Se,Te were respectively doped WS₂ model were established by using the CASTEP module in Materials Studio software.The four models were geometrically optimized.Based on the successful geometric structure optimization,the energy band structures,density of states,absorption spectra and reflection spectra of the four systems were calculated and the reason of the change of the forbidden band width was analyzed.Secondly,based on the supercell model of pure tungsten disulfide,the third cycle elements Si,P,Cl were chosen to substitute doping WS_2,and the superlattice models of different doping systems were established and the geometrical structure of the model was optimized.Based on the successful geometric structure optimization,the energy band structure,density of states,absorption spectra and refraction spectra were calculated.The effects of Si,P,Cl doping on the electronic structure and optical properties of WS₂ were analyzed.Finally,based on the supercell model of pure tungsten disulfide,the energy band structure,the density of states and the absorption of the doped system were calculated by substituting the same concentration of Te atom and Mo atom.The effects of co-doping on the electronic structure and optical properties of the crystalline materials were compared with the Te-Mo co-doping,Te doping and Mo doping.