Modulation of Electronic Structure of Armchair MoS Nanoribbon.

We perform first-principles calculations on electronic structures of armchair MoS2 nanoribbons (AMoS2NRs) passivated by non-metal atoms. In contrast to bare AMoS2NR (AMoS2NR-bare) or purely hydrogen (H) edge-terminated AMoS2NR (AMoS2NR-H), it is found that H and oxygen (O) hybrid edge-terminated AMoS2NR (AMoS2NR-H-O) is more stable. AMoS2NR-H-O exhibits a direct band gap of about 1.43 eV, which is larger than those of pristine AMoS2NR (about 0.61 eV) and AMoS2NR-H (about 0.60 eV), and even exceeds the band gap of bulk MoS2 (about 0.86 eV) and is close to that of monolayer MoS2 (about 1.67 eV). The remarkable band gap of AMoS2NR-H-O is attributed to the charge redistribution on the edge atoms of MoS2 nanoribbon, especially the charges on the edge Mo atoms. Detailed calculations of AMoS2NR-H-O reveal that over 70% of the total density of states (DOS) of the conduction band minimum and the valence band maximum are contributed by the Mo atoms. In particular, edge Mo atoms play a crucial role in modulating the electronic structure. In addition, we have studied a series of functionalized AMoS2NR-H-X with X = S, F, C, N, and P, respectively. It is found that AMoS2NR-H-X with X = S, 2F, C possess remarkable electronic band gaps, while AMoS2NR-H-X with X = F, N, P are metallic. Our studies suggest that non-metal atom hybrid passivation can efficiently tune the electronic band gap of MoS2 nanoribbon and open a new route to obtain MoS2 based practical nanoelectronic device and photo¬voltaic device.