Van der Waals force-induced intralayer ferroelectric-to-antiferroelectric transition via interlayer sliding in bilayer group-IV monochalcogenides

• Published in: npj computational materials Vol. 8; no. 1; pp. 1 - 9
• Main Authors: Xu, Bo, Deng, Junkai, Ding, Xiangdong, Sun, Jun, Liu, Jefferson Zhe
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 22.03.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/119/996; 639/925/357/1018; 639/925/927/1007; Antiferroelectricity; Bilayers; Characterization and Evaluation of Materials; Chemical bonds; Chemistry and Materials Science; Computational Intelligence; Covalent bonds; Crystal structure; Energy harvesting; Ferroelectric materials; Ferroelectrics; First principles; Germanium; Interlayers; Materials Science; Mathematical and Computational Engineering; Mathematical and Computational Physics; Mathematical Modeling and Industrial Mathematics; Molybdenum disulfide; Nanogenerators; Open circuit voltage; Piezoelectricity; Polarization; Size effects; Sliding; Theoretical; Tin; Two dimensional materials; Van der Waals forces
• ISSN: 2057-3960; 2057-3960
• DOI: 10.1038/s41524-022-00724-8

Two-dimensional materials with ferroelectric properties break the size effect of conventional ferroelectric materials and unlock unprecedented potentials of ferroelectric-related application at small length scales. Using first-principles calculations, a sliding-induced ferroelectric-to-antiferroelectric behavior in bilayer group-IV monochalcogenides ( MX , with M = Ge, Sn and X = S, Se) is discovered. Upon this mechanism, the top layer exhibits a reversible intralayer ferroelectric switching, leading to a reversible transition between the ferroelectric and antiferroelectric states in the bilayer MX s. Further results show that the interlayer van der Waals interaction, which is usually considered to be weak, can actually generate an in-plane lattice distortion and thus cause the breaking/forming of intralayer covalent bonds in the top layer, leading to the observed anomalous phenomenon. This unique property has advantages for energy harvesting over existing piezoelectric and triboelectric nanogenerators. The interlayer sliding-induced big polarization change (40  μ C cm −2 ) and ultrahigh polarization changing rate generate an open-circuit voltage two orders of magnitude higher than that of MoS 2 -based nanogenerators. The theoretical prediction of power output for this bilayer MX s at a moderate sliding speed 1 m s −1 is four orders of magnitude higher than the MoS 2 nanogenerator, indicating great potentials in energy harvesting applications.