Review of material properties of (Mo/W)Se2-layered compound semiconductors useful for photoelectrochemical solar cells

Molybdenum/tungsten dichalcogenides constitute a well-defined family of compounds which crystallize in a layer-type structure. These compounds have properties tailored for use as storage electrodes in rechargeable photoelectrochemical solar energy storage cells. These compounds find a wide range of applications in the field of catalysis and as lubricants at high temperatures and pressures. Among IV–VI semiconducting compounds, (Mo/W)Se2-layered compound dichalcogenides exhibit a hexagonal structure. The basic structural unit of such a compound is a sandwich of three planes: one plane of transition metal atoms between two halogen atoms. These sandwich-type structures are only loosely bound together through weak Van der Waals forces, and therefore, extremely anisotropic physical properties result. The material properties of the layered semiconductors, molybdenum diselenide (MoSe2), tungsten diselenide (WSe2) and molybdenum tungsten diselenide (Mo x W1 − x Se2), are prepared by different methods and presented in this review.