A type-II GeSe/SnS heterobilayer with a suitable direct gap, superior optical absorption and broad spectrum for photovoltaic applications

Abstract

Van der Waals (vdW) heterobilayers are emerging as unique structures for next-generation electronic and optoelectronic devices. In this work, we predict that the GeSe/SnS heterobilayer has a direct band structure with a gap value of about 1.519 eV and typical type-II band alignment. Moreover, it possesses the characteristics of superior optical absorption (∼10⁵) and a broad absorption spectrum from the visible light to the near ultraviolet region. In addition, the GeSe/SnS heterobilayer also exhibits obviously anisotropic electronic transport and optical properties with larger current and stronger optical absorption along the zigzag direction. Meanwhile, interlayer coupling and applying an external electric field are identified to be effective methods to modify its electronic and optical properties. Thus, these predicted results indicate that the GeSe/SnS heterobilayer will have promising applications in photovoltaic devices.