Giant Piezoelectricity of Janus M2SeX (M = Ge, Sn; X = S, Te) Monolayers

It is found that many two-dimensional materials are easy to obtain out-of-plane piezoelectric properties because of their Janus structure. Here, based on the monolayer GeSe and SnSe, we study the electronic structure and piezoelectricity of the Janus M2SeX (M=Ge, Sn; X=S, Te) monolayers. Due to the lack of inversion symmetry and mirror symmetry, as well as flexible mechanical properties, the 2D Janus M2SeX monolayers have large in-plane piezoelectric coefficients d(11) (up to 345.08pm/V) and out-of-plane piezoelectric coefficients d(31) (up to 3.83pm/V). All energy band structures of two-dimensional (2D) Janus M2SeX monolayers show indirect bandgap and Zeeman-type spin splitting after considering spin orbit coupling (SOC). The lack of mirror symmetry leads to out-of-plane spin polarization. In addition, the calculation based on the deformation potential theory shows that the 2D Janus M2SeX monolayers have high carrier mobility. The large piezoelectric properties and high carrier mobility show the application potential of 2D Janus M2SeX monolayers in flexible electronic devices and piezoelectric devices.

Automated summary

The two-dimensional Janus M2SeX monolayers exhibit large piezoelectric coefficients and high carrier mobility due to the lack of mirror symmetry and flexible mechanical properties, showing potential applications in flexible electronic devices and piezoelectric devices.