Intrinsic Coupling between Piezoelectric and Electronic Transport Properties in Janus γ-GeSnXO (X = S, Se) Monolayers with Vertical Piezoelectricity

Due to their properties and potential applications, two-dimensional (2D) materials have shown enormous advantages in electronic and piezoelectric devices. Unfortunately, few 2D materials have both higher piezoelectric effects and better mechanical durability. We predict the Janus γ-GeSnXO (X = S, Se) monolayer with practicable piezoelectric property and good mechanical durability based on density functional theory. The dynamic, thermodynamic, and mechanical stability results can prove it. In addition, the piezoelectric coefficient d33 is 1 to 2 orders of magnitude higher than that of the same type of piezoelectric material. The calculation results meet the law of the electronegativity difference ratio. The piezoelectric performance increases with the increase of the electronegativity difference ratio. Furthermore, there is an intrinsic coupling mechanism between piezoelectric and electronic transport properties in this work, where a smaller polarization electric field is accompanied by a larger carrier mobility. This research establishes a practical foundation to address the requirements of diverse piezoelectric nanodevices.