Theoretical Study On The Electronic Structure,magnetic And Optical Properties Of Triangular Graphyne Quantum Dots

?-Graphyne has the same topological structure as graphene,and also exhibits a Dirac cone energy band structure in the electronic structure.This unique electronic structure makes ?-graphyne to have ultra-high carrier mobility and excellent chemical stability.However,?-graphyne is a zero-band-gap semimetal,so it cannot directly achieve the “off” effect in electronic devices,which greatly limits its application in the field of nanoelectronics.People are committed to finding a way to open the band gap.Due to the simple structure and special physical properties of geometrically tailored zero-dimensional ?-graphyne quantum dots,it has important guiding significance for the research of graphyne-based nano-electronic devices and quantum devices.In addition,splicing ?-graphyne quantum dots into different quantum dot arrays is also an effective method to control the electronic structure of ?-graphyne,which will be an important concept in the practical application of manufacturing nano-integrated circuits in the future.Under this background,the triangle ?-graphyne quantum dots with zigzag boundary and armchair boundary are designed through geometric tailoring.Using the first-principles calculation method based on density functional theory,first,from the perspective of binding energy,the stability of graphyne quantum dots with different boundaries is analyzed;The band structure,density of state,spin state density,magnetic moment,dielectric function,reflection spectrum and absorption spectrum of ?-graphyne quantum dots with different boundary triangles are simulated and calculated.From the perspective of electronic structure,the electrical,optical and magnetic properties of ?-graphyne quantum dots are revealed.The results show that the structure of equilateral triangular graphyne quantum dots is stable,and as the size of quantum dots increases,the structural stability increases.The armchair graphyne quantum dots show a non-spin polarized ground state,and there is an obvious energy gap.And the size of the energy gap decreases as the size of the quantum dot increases.The zigzag graphyne quantum dots have a spin-polarized ground state,and the magnetic moment increases with the size of the quantum dots.The magnetism mainly comes from the electrons of the p-orbitals of the edge carbon atoms.Secondly,using different connection methods,the magnetic zigzag graphene quantum dots are arranged in an array structure.To study the electronic structure of quantum dot arrays in the case of non-magnetic,ferromagnetic and antiferromagnetic,the magnetic source mechanism of quantum dot arrays is analyzed from the perspective of density of state and wave function.The results show that,in the non-magnetic state,the quantum dot array with M1 and M2 connection shows semiconductor properties;the quantum dot array with M3 connection shows metallicity.In the ferromagnetic state,the quantum dot arrays with M1,M2,and M3 connections exhibit the characteristics of dual-polarized magnetic semiconductors.In the antiferromagnetic state,quantum dot arrays with M1,M2,and M3 connections appear as spin-simple semiconductors.Finally,the design and construction of the two-layer torsion structure zigzag graphyne quantum dots,the band structure,wave function,dielectric function,reflection spectrum and absorption spectrum of the torsion structure graphyne quantum dots were simulated and calculated.The relationship between the torsion angle and the energy gap of the torsion angle graphyne quantum dots is analyzed.The results show that the torsion angle will cause the interlayer coupling to change,which in turn will affect the energy gap and optical properties of the double-layer graphyne quantum dots.The research in this paper provides useful theoretical guidance for the experimental preparation of nano-electronic devices base on graphyne.