First-principles Study On Heterojunctions Composed Of Carbon Nanotubes And A GeSe Monolayer

Through van-der-Walls(vd W)interaction and integration of materials of different dimensions to form a heterojunction is a new method of designing materials.At present,the design of heterojunctions is mostly concentrated on two-dimensional and two-dimensional materials,and the research on the heterojunction of vd W integration between materials of different dimensions needs to be in-depth.Due to the integration of confinement effects of different dimensions,the heterojunctions formed by them can often exhibit excellent optoelectronic properties.Based on the van der Waals interaction,this paper considers the design of one-dimensional(1D)/two-dimensional(2D)nano-heterojunctions composed of one-dimensional carbon nanotubes(CNT)and two-dimensional germanium selenide(GeSe),and calculates the structure,electronic and optical absorption caracteistics of carbon nanotubes with different diameters through first-principles calculation.From the perspective of physical modeling and theoretical calculations,study the combination of the hot two-dimensional material GeSe and one-dimensional carbon nanotube materials that have received wide attention in recent years,and explore the stability of these heterojunctions,as well as electronic and optical properties.The conclusions obtained mainly include the following aspects:(1)A composite structure of two-dimensional GeSe and a series of zigzag(n,0)CNT(n=5-11)ware built,and the stability of these structures were considered from the perspective of binding energy.The binding energies were all negative,showed the stability of the model we built.The charge transfer at the interface was calculated,and it was found that all charges were transferred from GeSe to carbon nanotubes.(2)The electronic properties of the heterostructures were calculated,and their energy bands and density of states were analyzed.It was found that(n,0)CNT/GeSe(n=5-7)heterojunctions exhibit metallicity,while(n,0)CNT/GeSe(n=8-11)heterojunctions exhibit semiconductivity.The reason is that the energy band structures of carbon nanotubes of different tube diameters are different,which results in a change in the energy band structures of the heterojunctions.(3)The optical absorption coefficient and photoelectric conversion efficiency of the heterostructure were calculated.Two-dimensional GeSe itself has excellent performance in optical absorption.It was found that the optical absorption coefficient of(n,0)CNT/GeSe(n=8-11)heterojunctions were significantly enhanced,especially in the ultraviolet and infrared regions,which can reach 10⁵cm^-1 order of magnitude.According to Scharber's theoretical model calculation,it was found that the photoelectric conversion efficiency of(11,0)CNT/GeSe heterojunction can reach17.29%,which is comparable to PCE(16-18%)of double-layer phosphene/Mo S₂heterojunction.It has potential applications in photovoltaic devices.