Rational design of SiC/SnSSe heterostructure for efficient photovoltaic and photocatalytic applications

The search for highly efficient and eco-friendly photocatalysts and photovoltaic solar cells is now in progress, however, it still remains challenging. By first-principles calculations, we demonstrate that Janus SiC/SnSSe van der Waals heterostructures (vdWHs) with a typical type-II band alignment possess great potential in photocatalytic and photovoltaic applications. An intrinsic electric field induced by the Janus feature of SnSSe alongside an interfacial built-in electric field caused by charge transfer from SiC to SnSSe monolayer significantly fosters spatial separation of photogenerated electron-hole pairs in two layers. Since the reduced bandgap of the vdWHs promotes an enhancement of optical absorption in the visible and even infrared regions in comparison with that of their constituting monolayers, the solar-to-hydrogen conversion efficiency reaches as high as 41.5 %, making it a highly efficient photocatalyst. The high photoresponsivity in the visible region endows the proposed system with a powerful potential for photovoltaic applications. Besides, we also find that the optical absorption and photocurrent can be effectively tuned by applying biaxial strains. For instance, the latter increases to 31 % at 4 % tensile strain. These findings provide new prospects for designing direct Z-scheme photocatalysts and photovoltaic devices based on vdWHs.