Photostriction-tunable Polarization and Structural Dynamics in Interlayer Sliding Ferroelectrics

TL;DR

This study reveals how light-induced lattice expansion in bilayer MoS2 can modulate ferroelectric polarization and bandgap, highlighting a strong electromechanical coupling in sliding ferroelectrics for advanced device applications.

Contribution

It demonstrates photostriction effects in bilayer MoS2, showing how photodoping induces lattice expansion and polarization changes, a novel insight into light-controlled ferroelectric dynamics.

Findings

Photodoping causes in-plane lattice expansion and increased interlayer spacing.

Electron-hole excitation enhances ferroelectric polarization.

Bandgap undergoes significant renormalization due to strain.

Abstract

Two-dimensional ferroelectrics with robust polarization offer promising opportunities for non-volatile memory, field-effect transistors, and optoelectronic devices. However, the impact of lattice deformation on polarization and photoinduced structural response remains poorly understood. Here, we employ first-principles calculations to demonstrate photodoping-induced lattice expansion in rhombohedrally stacked bilayer MoS2, revealing a strong coupling between photodoping carrier and lattice structure. We identify a pronounced photostrictive response in sliding ferroelectrics, wherein electron-hole excitation leads to substantial in-plane expansion, increased interlayer spacing, and enhanced ferroelectric polarization. This strain-induced modulation drives significant bandgap renormalization. The photostriction-tunable polarization and structural dynamics arise from the strong electromechanical coupling inherent to the non-centrosymmetric rhombohedral stacking. The findings provide critical insights into the nonthermal lattice expansion governing sliding ferroelectrics at atomic-scale timescales, while simultaneously laying the groundwork for next-generation electronic and memory technologies by leveraging lattice-tunable polarization switching.