Layer-dependent optoelectronic properties of black phosphorus.

The layer-dependent optoelectronic properties of monolayer, bilayer and trilayer black phosphorus (BP) are studied by using the first-principles calculations based on density functional theory (DFT). The valence band splits and the density of states (DOS) in the conduction band obviously shift to the Fermi surface with the increased layer number. The atomic p orbital of BP plays an decisive role in determining the electronic and optical properties, which are drastically different from those of graphene and transition metal dichalogenides (TMDs). The increase of the layer number leads to the metal characteristics. The extinction coefficient and photoconductivity show strong optical responses to the ultraviolet (UV) light, which further increase with the number of layers. BP layers can reflect UV rays effectively because of their metallic properties in the UV energy range. Our study shows that the interlayer interaction can intensely change the electronic and optical properties of BP. [ABSTRACT FROM AUTHOR]