Effective strategy of enhancing piezoelectricity in stable CrSiN₄Sn semiconductor monolayers by atom-layer-pair effect

It is challenging to reveal the design strategy for strong piezoelectricity nano-materials used in self-powered and smart nano-devices. Through first-principles calculations, an atom-layer-pair effect is found in MoSi_xN_yR_z monolayers with remarkable piezoelectricity. The absolute values of the vertical piezoelectric coefficients have a linear relation with the total electronegativity difference dipole moments. Based on this effect, a promising CrSiN₄Sn monolayer is found with the highest piezoelectricity among the above monolayers. The work expands our understanding of the piezoelectric physical mechanism and provides the design strategy for piezoelectric nano-devices.