Issue 42, 2019

Two-dimensional MgX2Se4 (X = Al, Ga) monolayers with tunable electronic properties for optoelectronic and photocatalytic applications

Abstract

Two new two-dimensional (2D) layered materials, namely, MgX2Se4 (X = Al, Ga) monolayers, are predicted to possess novel electronic properties. Ab initio electronic structure calculations show that both MgAl2Se4 and MgGa2Se4 monolayers are direct-gap semiconductors with bandgaps of 3.14 eV and 2.34 eV, respectively. The bandgap of both 2D materials is very sensitive to the in-plane biaxial strain, while the strain induced bandgap changes allow the tuning of optical absorption from the violet to green-light region. Also importantly, the in-plane electron mobility of both 2D materials is predicted to be as high as ∼0.7–1.0 × 103 cm2 V−1 s−1, notably higher than that of the MoS2 sheet (∼200 cm2 V−1 s−1), while it is comparable to that of black phosphorene (∼1000 cm2 V−1 s−1), suggesting their potential application in n-type field-effect transistors. Moreover, suitable bandgap and band-edge alignment make the monolayer MgX2Se4 a potential photocatalyst for water splitting. Lastly, we show that MgX2Se4 possesses a lower monolayer cleavage energy than that of graphite, indicating easy exfoliation of MgX2Se4 layers from their bulk.

Graphical abstract: Two-dimensional MgX2Se4 (X = Al, Ga) monolayers with tunable electronic properties for optoelectronic and photocatalytic applications

Supplementary files

Article information

Article type
Paper
Submitted
31 Aug. 2019
Accepted
25 Sept. 2019
First published
26 Sept. 2019

Nanoscale, 2019,11, 19806-19813

Two-dimensional MgX2Se4 (X = Al, Ga) monolayers with tunable electronic properties for optoelectronic and photocatalytic applications

P. Li, W. Zhang, C. Liang and X. C. Zeng, Nanoscale, 2019, 11, 19806 DOI: 10.1039/C9NR07529A

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