Anomalous Anisotropy of the Piezoelectric Response in 2D Copper‐Based Ternary Chalcogenides CuMX2

Abstract

The development of 2D materials with excellent electronic properties and piezoelectric response is clearly critical for multifunctional piezoelectric devices. Herein, based on first‐principles calculations, the electronic, mechanical, and piezoelectric properties of a series of 2D copper‐based ternary chalcogenides, denoted as CuMX2 (M = Sb and Bi; X = S and Se) monolayers, are systematically studied, which can be obtained by exfoliating from their bulk counterparts. The calculations show that these ternary CuMX2 monolayers exhibit desirable dynamical and thermal stabilities and moderate bandgaps. The calculated piezoelectric coefficients and of these monolayers are in the range of 0.44–6.14 and 9.13–29.52 pm V−1, respectively, which exceed or approach those of most well‐studied 2D systems. Interestingly, as compared with other reported 2D systems, the CuMX2 monolayers exhibit an anomalous anisotropy of piezoelectric response, manifested as the larger coefficient than coefficient . The study demonstrates that the CuMX2 monolayers are potential 2D candidates in nanoelectric and nanopiezoelectric devices.