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 CuMX 2 (M ¼ Sb and Bi; X ¼ S and Se) monolayers, are systematically studied, which can be obtained by exfoliating from their bulk counterparts. The calculations show that these ternary CuMX 2 monolayers exhibit desirable dynamical and thermal stabilities and moderate bandgaps. The calculated piezoelectric coefficients d 11 and d 12 of these monolayers are in the range of 0.44-6.14 and 9.13-29.52 pm V À1 , respectively, which exceed or approach those of most well-studied 2D systems. Interestingly, as compared with other reported 2D systems, the CuMX 2 monolayers exhibit an anomalous anisotropy of piezoelectric response, manifested as the larger coefficient d 12 than coefficient d 11 .The study demonstrates that the CuMX 2 monolayers are potential 2D candidates in nanoelectric and nanopiezoelectric devices.

Theoretical design and discovery of two‐dimensional materials for next‐generation flexible piezotronics and energy conversion

“…Copper based ternary chalcogenides, too, have the potential for planar multidirectional piezoelectric applications. $${\text{CuBiS}}_{2}$$ has largest $${{\rm{e}}}_{11}$$ coefficient, while $${\text{CuSbSe}}_{2}$$ has largest $${{\rm{e}}}_{12}$$ component [69]. A family of hexagonal Groups III–V semiconductors can acquire two stable structures planar and buckled depending on the electrostatic potential energies and $${\text{sp}}^{2}$$–$${\text{sp}}^{3}$$ hybridization of the ions.…”

Ultrafast dynamics under high-pressure

“…2D materials have unique physical and chemical properties as a result of their spatial structure, such as strong exciton binding energy induced by weak Coulomb screening effect, and thus have important and wide applications in the fields of catalysis, energy storage and sensors. In recent years, scientists have conducted deep research on layered 2D materials, such as graphene, metal-sulfur compounds, metal hydroxides, etc, for which the exciton behavior is sensitive due to the 2D structure [74][75][76]. In 2D materials, exciton behavior is decided not only by the quantum confinement effect in the horizontal direction, but also by weak van der Waals (vdW) interactions between layers in the vertical direction.…”

In situ vulcanization synthesis of CuInS2 nanosheet arrays for a memristor with a high on–off ratio and low power consumption

“…Despite their dimensionality, 2D copper chalcogenides could make a crucial difference in determining their properties and integration; [13][14][15] the electronic properties and applications of these materials have rarely been researched compared to their bulk or film forms. 14,[16][17][18] In view of the memristive properties, most 2D memristors possess a switching voltage larger than 1 V compared to copper chalcogenides.…”