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Benzene-like N6 Rings in Be2N6 Monolayer: a Stable 2D Semiconductor with High Carrier Mobility

Abstract

Designing new two-dimensional (2D) semiconductors with high carrier mobilities is highly desirable for the material innovation, especially when the configuration has novel topological properties. Here, we proposed a first-principles-based design of a 2D crystal, namely Be2N6 monolayer. In which, each N atom is shared by two neighboring N atoms and one Be atom, forming a novel moiety of benzene-like N6 rings. Rather than the instability of hexazine, Be2N6 monolayer has a moderate cohesive energy, good kinetic and thermodynamic stability, due to the stabilization effect of the Be element by forming twelve classical two-centre-two-electron (2c–2e) σ-bonds and five multicenter 6c–2e π-bonds. There are ten π electrons in a unit cell, which satisfies the Hückel rule [4n + 2] (n=2), indicating Be2N6 monolayer aromaticity. As a result, Be2N6 monolayer has an ultra-high mechanical strength of up to 200 J m-2. The particle-swarm optimization (PSO) computations reveal that cyclo-N6-containing Be2N6 monolayer is the lowest-energy configuration in 2D forms with a stoichiometry of 1: 3, and therefore could be synthesized experimentally. Furthermore, Be2N6 monolayer is an indirect semiconductor with a band gap of 1.71 eV at the hybrid functional level, close to that of the bulk amorphous silicon ~1.6 eV widely used in solar cells. At this point, the high electron mobility of up to ~104 cm2 v-1 s-1 and visible-light absorption of ~105 cm−1 are observed for Be2N6 monolayer. If realized, it will not only enrich the knowledge of the bonding nature of nitrogen but also could have potential applications in electronics and optoelectronics.

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Publication details

The article was received on 26 Jul 2017, accepted on 02 Oct 2017 and first published on 03 Oct 2017


Article type: Paper
DOI: 10.1039/C7TC03363J
Citation: J. Mater. Chem. C, 2017, Accepted Manuscript
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    Benzene-like N6 Rings in Be2N6 Monolayer: a Stable 2D Semiconductor with High Carrier Mobility

    F. Li, Y. Wang, H. Wu, Z. Liu, U. Aeberhard and Y. Li, J. Mater. Chem. C, 2017, Accepted Manuscript , DOI: 10.1039/C7TC03363J

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