四种新型磷烯电子结构及光学性质的第一性原理研究

First-principles studies electronic structures and optical properties of four new phosphorene polymorphs

黑磷(α-P)是兼具石墨烯和二维过渡族金属硫化物优点的新型二维材料,近期成功预测的新型磷烯ε-P,ζ-P和θ-P,具有与黑磷相似的蜂窝状褶皱结构.本文采用第一性原理方法,研究了4种新型磷烯(α-P,ε-P,ζ-P和θ-P)的电子结构及光学性质.结果表明:α-P和ε-P为具有1.542和0.973 eV直接带隙的半导体,ζ-P和θ-P为具有1.874和1.772 eV间接带隙的半导体;它们均表现出强烈的紫外吸收和紫外反射,可用作紫外探测设备或紫外防护材料,能量损失集中在紫外区域,具有良好的储光性能.

Black phosphorus（α-P）, a new member of two-dimensional（2D） materials, which has the common advantages of graphene and transition metal dichalcogenides（TMDs）, is of great concern. Based on the studies of black phosphorus,three new monolayer phosphorene polymorphs（ε-P, ζ-P, and θ-P） have been predicted recently, which greatly enrich the phosphorene structures. Three new monolayer phosphorene polymorphs, composed of P4 square units（ε-P, ζ-P） or P5 pentagon units（θ-P）, all exhibit buckled honeycomb lattices akin to black phosphorus. Remarkably, the θ-P is equally stable as the black phosphorus, and more stable than the other two new phosphorene polymorphs. In this paper, electronic structures and optical properties of monolayer black phosphorus（α-P） and three new monolayer phosphorene polymorphs（ε-P, ζ-P and θ-P） have been investigated based on the first-principles density functional theory（DFT）. In comparison with Perdew-Burke-Ernzerh of generalized gradient approximation（GGA-PBE） with ultra-soft pseudopotential, hybrid density functional（HSE06） with norm-conserving pseudopotential is selected for subsequent calculation, because it is closer to experimental data. The calculation results show that, α-P and ε-P are direct semiconductors with band gaps of 1.542 and 0.973 eV, respectively. ζ-P and θ-P are indirect semiconductors with band gaps of 1.874 and 1.772 eV, respectively. Based on the electronic properties, the optical properties are discussed in detail.It is found that α-P and three new monolayer phosphorene polymorphs have good permeability in the whole infrared and visible region, which means that they can be used as optical transparent materials. Moreover, the peaks of reflectance and absorption spectra are in the ultraviolet region, indicating that they can be used as ultraviolet protection materials or ultraviolet detection equipment. This research is aimed at enhancing the understanding of the photoelectric properties ofα-P and three new monolayer phosphorene polymorphs, and providing an useful theoretical basis for the practical application as photoelectric materials.