How to enhance the polarization intensity of two-dimensional sliding ferroelectricity for hexagonal boron- or nitrogen-based binary compounds?

In recent years, two-dimensional sliding ferroelectric materials have received widespread attention due to their unique ferroelectric mechanism, which exists in van der Waals bilayer and multilayer systems. However, compared to traditional ferroelectric materials, their relatively weak polarization intensity and low energy barrier limit their practical applications. Here, using the first-principles calculations, we focus on hexagonal layered structures formed by group III-V elements and propose a design principle that utilizes bilayer materials composed of elements with significant differences in atomic electronegativity to address this issue. The results show that materials composed of two atoms with significant electronegativity differences can effectively increase the polarization intensity and possess moderate energy barriers. Furthermore, the polarization intensity can be effectively modulated by adjusting interlayer distance. The research findings have important significance for the exploration of other two-dimensional sliding ferroelectric materials with high polarization intensity.&#xD.