Strain Engineering the Ferroelectric Polarization and Optical Absorption in the FEβ-In2Se3 Monolayer

The van der Waals (vdW)-layered material In2Se3, known for exhibiting spontaneous ferroelectricity at room temperature, has promising applications in nonvolatile memory and advanced optoelectronics. In this work, we report on a strong coupling between strain, ferroelectricity, and optical absorption in the monolayer FEβ-In2Se3. Based on the density functional theory calculations, the monolayer FEβ-In2Se3 has an in-plane spontaneous polarization of 2.109 × 10–10 C/m, seven times larger than that of the reported α-In2Se3. It is found that the external strain can be used as an effective method to modulate the direction and magnitude of ferroelectric polarization. Moreover, our calculations indicate that in-plane polarization will further influence the light absorption anisotropy and absorbance of FEβ-In2Se3. The tunability of strain on the optic properties enables us to design FEβ-In2Se3-based logic devices where the information is read by the light absorption signal. These studies are not only of scientific interest in the interplay between strain and ferroelectric polarization in FEβ-In2Se3 but also open a new path to explore the electronic application of the ferroelectric vdW materials.