First-principle study on the optical response of phosphorene

The optical response of phosphorene nanostructures was studied using time-dependent density functional theory (TDDFT). Compared with the absorption spectrum of graphene, that of the phosphorene nanostructure exhibits high absorbance in the ultraviolet region, which indicates a high light absorptivity. In a low-energy resonance zone, a spectral band extends to the entire near-infrared regions. When the impulse excitation polarizes in the armchair-edge direction, the low-energy plasmon in a few-layer phosphorene nanostructure shows an apparent long-range charge-transfer excitation but is significantly less pronounced along the zigzag-edge direction. The edge configuration significantly affects the absorption spectrum of monolayer phosphorene nanostructures. The armchair-edge and the zigzag-edge serve different functions in the absorption spectrum. Moreover, the absorption spectrum of the few-layer phosphorene nanostructure changes with the number of layers when the impulse excitation polarizes in the armchair-edge direction. In addition, the change in the low-energy resonance zone is significantly different from that in the high-energy resonance zone.