Multidirectional Intrinsic Piezoelectricity of 2D Metal Chalcogen–Diphosphate ABP<sub>2</sub>X<sub>6</sub> Monolayers
Shujuan Jiang, Huabing Yin, Jingyu Li, Lu Liu, Xiaobo Shi, Yuli Yan, Chang Liu, Guangping Zheng, Pengfei Liu
Abstract
Due to the simultaneously broken inversion symmetries along multiple directions, ABP 2 X 6 (A = Cu or Ag, B = In or Bi, and X = S or Se) monolayers exhibit the coexistence of sizable piezoelectric coefficients d 11 , d 21 , and d 31 , under unidirectional in‐plane strains or stresses, as determined from first‐principles calculations. Remarkably, the AgBiP 2 S 6 and AgBiP 2 Se 6 monolayers possess d 11 coefficients of 17.33 and 17.25 pm V −1 , respectively; these are much higher than those of extensively studied 2D piezoelectric materials. Meanwhile, the out‐of‐plane d 31 coefficient of AgBiP 2 Se 6 is as high as 0.36 pm V −1 . The ABP 2 X 6 monolayers possessing unique multidirectional piezoelectricity pave novel avenues for the application of piezoelectric devices with multiple functions.