层数调控磷烯能带与光学性质的研究

Layer-dependent band structure and optical properties of black phosphorene

近年来,黑磷作为兼具石墨烯和过渡金属硫化物之长的新型二维材料而倍受关注.本文基于密度泛函理论,研究了不同厚度黑磷的电子结构与光学性质.结果表明,黑磷的性质与其厚度密切相关,可通过厚度调整实现能带与光学性质的可调控性.层间相互作用导致费米能级附近价带和导带的劈裂,是造成黑磷带隙随层数减小的根本原因.黒磷的静态折射率和静态反射率的大小均随层数的增大有增大的趋势,并且各层黑磷的反射峰均位于紫外光波段.黑磷对光的吸收涵盖了可见光到紫外光区域,对光的损失范围小于4eV.本文基于能带图和分波态密度图,从电子跃迁的角度分析了黑磷各项光学性质的变化情况,旨在为黑磷的带隙及光学性质层数可调控性提供理论依据.

Recently,black phosphorus(BP),a new type of2D material combining advantages of graphene and transition metal dichalcogenides,is of great concern.Investigations show that many excellent properties of black phosphorus are layer-dependent.In this paper,the effects of layer number on the band structure,density of states,optical properties of BP have been studied by using the first-principles calculations based on density function theory(DFT).Based on comparative analysis of band structure and density of states,it is found that band gap decreases with the increase of layer number in few-layer BP because of the splitting of energy bands induced by the inter-layer interactions.The analysis of optical properties shows that the static refractive index and the static reflectivity increase with the increase of the number of layers.Meanwhile,the reflection peaks of each layer of BP are located in the ultraviolet band.The absorption of BP to light covers the range from visible light to ultraviolet region.The variation trends of the dielectric function,refractivity,reflectivity,absorption,loss function and conductivity of BP are further analyzed on the basis of band structure and partial density of states(PDOS),which provides a useful theoretical foundation for the photoelectric application of BP.