Issue 23, 2022

Prediction of 2D IV–VI semiconductors: auxetic materials with direct bandgap and strong optical absorption

Abstract

Auxetic materials are highly desirable for advanced applications because of their negative Poisson's ratios, which are rather scarce in two-dimensional materials. Motivated by the elemental mutation method, we predict a new class of monolayer IV–VI semiconductors, namely, δ-IV–VI monolayers (GeS, GeSe, SiS and SiSe). Distinctly different from the previously predicted IV–VI monolayers, the newly predicted δ-MX (X = Ge and Si; M = S and Se) monolayers exhibit a puckered unit cell with a space group of Pca21. Their stabilities were confirmed by first-principles lattice dynamics and molecular dynamics calculations. In particular, all these MX monolayers possess a large bandgap in the range of 2.08–2.65 eV and pronounced anisotropic mechanical properties, which are demonstrated by direction-dependent in-plane Young's moduli and Poisson's ratios. Furthermore, all these 2D MX monolayers possess negative Poisson's ratios (even up to about −0.3 for SiSe). Strong optical absorption is observed in these δ-IV–VI monolayers. These interesting physical properties will stimulate the development of 2D flexible devices based on IV–VI semiconductor monolayers.

Graphical abstract: Prediction of 2D IV–VI semiconductors: auxetic materials with direct bandgap and strong optical absorption

Supplementary files

Article information

Article type
Paper
Submitted
11 fev 2022
Accepted
07 may 2022
First published
20 may 2022

Nanoscale, 2022,14, 8463-8473

Prediction of 2D IV–VI semiconductors: auxetic materials with direct bandgap and strong optical absorption

K. Ren, X. Ma, X. Liu, Y. Xu, W. Huo, W. Li and G. Zhang, Nanoscale, 2022, 14, 8463 DOI: 10.1039/D2NR00818A

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