Phosphorene oxides: Bandgap engineering of phosphorene by oxidation

We show that oxidation of phosphorene can lead to the formation of a new\nfamily of planar (2D) and tubular (1D) oxides and sub-oxides, most of them\ninsulating. This confers to black phosphorus a native oxide that can be used as\nbarrier material and protective layer. Further, the bandgap of phosphorene\noxides depends on the oxygen concentration, suggesting that controlled\noxidation can be used as a means to engineer the bandgap. For the oxygen\nsaturated composition, P$_2$O$_5$, both the planar and tubular phases have a\nlarge bandgap energy of about 8.5eV, and are transparent in the near UV. These\ntwo forms of phosphorene oxides are predicted to have the same formation\nenthalpy as o$^\\prime$-P$_2$O$_5$, the most stable of the previously known\nforms of phosphorus pentoxide.\n