Bending deformation regulates the electronic and optical properties of black phosphorene

The electronic and optical properties of black phosphorene with different bent angle are studied using density functional theory based on the first-principles. Within the scope of our study, it was found that the phosphorene becomes less stable with the increasement of bending deformation. Bending deformation has great impact on the electronic and optical properties on phosphorene. The bandgap degrades a little at 2.5 degrees bent angle, and then increases when the bent angle does not surpass 15 degrees, after which the bandgap decreases with the increasement of bending deformation. Besides, the bandgap of black phosphorene occurs a direct to indirect transition at 19 degrees bent angle. The bandgap calculated by HSE06 is larger than PBE functional, but the law of changes is consistent. By analyzing the density of states, we concluded that all the undeformed and deformed phosphorene structures have a strong sp orbital hybridization. Besides, the p orbits have narrower gap than s orbits, which causes the narrower bandgaps of these structures. From the analysis of optical properties, we concluded that the black phosphorene with 7.5 degrees bent angle has the highest absorption coefficient. All structures under bending deformation have higher reflectivity peak than intrinsic black phosphorene, among these structures, the black phosphorene with 27.5 degrees bent angle has the highest reflectivity. The novel optical property is observed at the 20 degrees deformed structure, it stops absorbing (reflecting) light first. Redshift and blueshift phenomena are observed at the highest absorption peak and reflectivity peak.