Quantum confinement and edge effects in zigzag green phosphorene nanoribbons*

Ab initio calculations were carried out to study size and edge effects on the electronic properties of zigzag green phosphorene nanoribbons (ZGPNRs) with edge chemical functionalization including H, OH, F, Cl, O, and S for the ribbon width up to 3.7 nm. The electronic properties of the ZGPNRs are strongly dependent on the ribbon width and edge chemical species. The ribbons are either semiconducting or metallic depending on the edge functionalization species. The ZGPNRs demonstrate semiconducting behavior with the edge passivation of H, OH, F, or Cl (Group I), while show metallic feather with pristine or O, S edges (Group II). The conduction band minimum (CBM) and valence band maximum (VBM) of the ZGPNRs with the Group I edges are mainly contributed by the inner P atoms and the edge P and functionalization atoms have little contribution. However, for the Group II edges, the electronic bands crossing the Fermi level are dominantly located at the edge atoms. It was also found that the band gap and work function of the ZGPNRs are tunable by varying ribbon width and edge functionalization species.