Study Of Adjustable Photoelectric Properties Of Bilayer/Trilayer Two-Dimensional Blue Phosphorus/Molybdenum Disulfide(Diselenide)Heterostructures

The research and application fields of two-dimensional materials are becoming more and more extensive,and they have shown great application potential in the fields of new energy devices,optoelectronic devices,photocatalysis and solar cells.The combination of materials with different electronic and optical properties can obtain the desired structure,and the vertical stacking or lateral stacking of heterostructures of two-dimensional materials provides a variety of possibilities for the design and actual manufacturing of optoelectronic devices.Two-dimensional monolayer blue phosphorene(Blue P)and transition metal chalcogenides(TMDCs)have been successfully prepared by experiments,and have been verified to have good electronic properties,high electron mobility and flexibility,which are potential candidates for next-generation optoelectronic and photovoltaic devices.In this paper,the electronic,molecular dynamics and optical properties of bilayer/trilayer Blue P/Mo X₂(X=S,Se)heterostructures are systematically studied by first principles and density functional theory.Under the conditions of applying external electric field and stress,the optoelectronic properties of heterostructures have been studied for application in the fields of photocatalysis and photovoltaic devices.The research process of this article is as follows:This paper first calculated lattice parameters of the monolayer blue phosphorene and molybdenum disulfide(selenium)materials,and the lattice mismatch rate of less than 4%indicates the good matching of the heterostructure.Furthermore,six different configurations of bilayer/trilayer Blue P/Mo X₂(X=S,Se)van der Waals(vd W)heterostructures were constructed,and the binding energy values calculated by structural optimization are all negative values,which represent the good stability and practical preparation possibilities of all heterostructures.Compared with the PBE functional,the energy band gap calculated by the HSE06functional is more in line with the experimental value.In the trilayer heterostructures,the charge analysis of Bader shows that the charge transferred from Blue P layer to Mo S₂ layer is more than Blue P layer to Mo Se₂ layer.The calculated electronic localization function indicates that the force between the layers is not a strong covalent bond or a weak ionic bond,but a weak van der Waals force.Subsequently,this paper analyzed the electrostatic potential and charge density difference of the Blue P/Mo X₂(X=S,Se)heterostructure.The larger potential voltage drop and charge accumulation and depletion built on the interface indicate that a relatively strong built-in electric field will inevitably form between layers.The formation of such a strong built-in electric field will hinder the recombination of electron-hole pairs,resulting in an increase in the carrier mobility of the heterostructure.In the next chapter,the molecular dynamics and raman spectra of the bilayer/trilayer Blue P/Mo X₂(X=S,Se)heterostructure are calculated.The phonon dispersion and the 10 ps molecular dynamics simulation both indicate the heterogeneity and mechanical stability of the heterostructure at room temperature.However,due to the different number of layers of monolayer materials,the thermodynamic properties and raman spectra of the heterostructure have been improved and shifted.Finally,when an external electric field or vertical strain is applied to the bilayer/trilayer Blue P/Mo X₂(X=S,Se)heterostructure,the electronic properties of the heterostructure can be well adjusted due to the interlayer coupling and the stark effect.Such good controllable characteristics inspired us to apply it to electronic transistor devices and piezoelectric devices.Subsequently,this paper continued to calculate the dielectric function,light absorption coefficient and optical conductivity of the bilayer/trilayer Blue P/Mo X₂(X=S,Se)heterostructure.With the increase of the number of layers,the light response range and optical properties of the heterostructure have also been greatly improved.The band edge alignment calculation shows that the heterostructure has good photocatalytic properties.In this paper,we also calculated the solar energy conversion efficiency(PCE)of the heterostructure to study the application potential of solar cells.The calculated PCE value of the bilayer heterostructure is not much different,Blue P/Mo S₂ is 14.35%,Blue P/Mo Se₂ is 14.12%.In the trilayer heterostructure,the PCE value of Blue P/Mo Se₂/Blue P is as high as 19.34%,while the PCE value of Mo Se₂/Blue P/Mo Se₂ is only 14.72%.The excellent PCE value makes the heterostructure theoretically applicable to the field of photovoltaic solar cells,and the PCE value can be improved by adjusting the conduction band offset of different layers of the heterostructure.