Theoretical Design And Optoelectronic Properties On The Derivatives Of Two-dimensional Arsenene And Antimonene

Arsenene and antimonene,monolayer arsenic and antimony,was predicted as a two-dimensional(2D)semiconductors with blue and UV photoresponse because of their wide band gaps.Inspired by the extensive investigations of arsenene and antimonene,researchers have also devoted much concern to those derivatives,and much progress has been made in this emerging new area.However,the applications of its derivatives in some optoelectronics fields,especially energy,are still less studied or even absent.In this thesis,based on first-principles calculations,we have systematically studied the derivatives of arsenene and antimonene in view of their fundamental properties(i.e.,geometrical,electronic properties)and functional applications(i.e.,field effect transistors(FET),solar cells and thermophotovoltaic cell).The main contents of this thesis include following four aspects:1.Research on the chemical doping of antimonene by organic moleculesChemical doping is an effective approach to tune the bandgap on semiconductors.In order to realize the tune the electronic structure of antimonene,the theoretical model of antimonene is developed to analyze the chemical doping effects of TTF and TCNQ by comprehensive first-principles calculations.By the strong electron-donating(tetrathiafulvalene,TTF)modified antimonene,we obtain an n-type semiconductor with a deep donor state of 0.73 eV.Importantly,by the strong electron-accepting(tetracyanoquinodimethane,TCNQ)functionalized antimonene,a p-type semiconductor is achieved with a shallow acceptor state of 0.27 eV.Moreover,the co-adsorption of TTF and TCNQ on the antimonene with one-and two-side models,can attain p-type semiconductors with shallow donor state of 0.15 and 0.12 eV.No matter what kind of doping and models,there has interfacial charge transfer between organic molecules and antimonene.2.Research on van der Waals bilayer antimonene for thermophotovoltaic cellsMotivated by the experimental prepared of few-layer antimonene with AB-and ABC-stacking,as well as multilayer van der Waals(vdW)antimonene with non-zero bandgap,we design the 2D stacking various types for vdW bilayer and trilayer grey antimony.All different stacking vdW bilayers and trilayers are high thermodynamic stability via phonon spectra.AB-stacking vdW bilayer antimonene convert into metallic behavior,while A A-and AC-stacking vdW bilayers still maintain the semiconducting behavior.All vdW trilayers also own the metallic behavior,similar with AB stacking vdW bilayer antimonene.Importantly,the AC-stacking vdW bilayer antimonene exhibited a bandgap of 0.62 eV,falling into the optimum range of the thermophotovoltaic(TPV)requirement(0.35-0.75 eV).Such a decisive advantage enables the AC-stacking vdW bilayer antimonene to be a very promising material for high-efficient TPV cell,which has been evidenced by an energy conversion efficiency of 31%for the foremost designed vdW bilayer Sb/AC-based TPV.It is exceeding the traditional TPV materials such as Ge and GaSb.3.Research on ultrahigh carrier mobility of monolayer BX(X=P,As,Sb)Carrier mobility plays a key role in the performance of microelectronic devices,especially the field effect transistors(FET).To design next generation two-dimensional(2D)FET,stable channel materials with higher carrier mobility than silicon and significant band gap are highly desirable,but still not discovered.We find that all BX(X=P,As,Sb)configurations are similar to graphene,but possess direct bandgaps of 1.36,1.14,and 0.49eV,respectively.Such numerical values satisfy the requirement of on/off ratio(>0.4eV).Based on deformation potential theory,BX monolayers are predicted to have superior mobilities(>104 cm2V-1s-1)to phosphorene.Especially,the electron mobility of monolayer BSb is 3.2×105 cm2V-1s-1,approaching the figure of merit in graphene(～3×105 cm3V-1s-1).These results demonstrate that BX monolayers are of paramount significance for next-generation 2D FET manufacture.4.Research on black monolayer arsenic-phosphorus for solar cellsSolar cell is an important kind of optoelectronic devices in the field of erngy utilization.While low power conversion efficient(PCE)of traditional solar cells are found.Based on the experimental systheis of few-layer arsenic—phosphorus,as well as the therotical report of five monolayer phosphorus allotropes,monolayer arsenic-phosphorus polymorphs with α,β,δand ε phases are built.All monolayer arsenic-phosphorus polymorphs show high stability,especially α and β-AsP phases.Significantly,monolayer α-AsP possesses a direct bandgap with energy of 1.54 eV,which covers the main energy of solar spectrum.Moreover,its electronic mobility is as high as 14,380 cm2V-1s-1,which is much higher than silicon.These two crucial merits made it a promising candidate as donor materials for XSC device and the theoretical simulations demonstrate a maximum PCE of 22.1%for the primarily designed a-AsP/GaN solar cells.