The optoelectronic properties in two-dimensional sliding ferroelectric material XC (X = Ge, Si) under strain

Two-dimensional sliding ferroelectricity has attracted significant attention owing to its unique reversible out-of-plane polarization generated by interlayer sliding. Numerous materials have been experimentally verified to demonstrate this phenomenon. In this work, bilayer honeycomb XC (X = Ge, Si) is investigated using the first-principles calculations to explore the ground state structure, electronic, transport and optical properties. First, the most stable AB configuration is identified, and its electronic structure is studied and modulated via strain engineering. Results indicate that the band gap gradually decreases as the strain transitions from compressive to tensile. Furthermore, the carrier mobility and optical absorption of AB-stacked XC (X = Ge, Si) are researched, revealing exceptionally high mobility that can be effectively tuned within the strain range of −8 %–8 %. Additionally, the optical absorption coefficient of the system presents the phenomenon of red-shift in sequence from compressive to tensile strain. These findings provide valuable insights into the photovoltaic potential of sliding ferroelectrics, suggesting promising applications in photovoltaics, solar cells, and optoelectronic devices.