WS2 and WSSe bilayer with excellent carrier mobility and power conversion efficiency

The WS2/WSSe and WSSe/WS2 bilayers are constructed using single-layer WS2 and WSSe with a lattice mismatch rate of only 1.85 %, and their structural properties, carrier mobility, electrical properties, and photocatalytic performance are performed using density functional theory. The carrier mobility of WS2/WSSe and WSSe/WS2 bilayers is better than that of single-layer WS2. And the conductivity of the WSSe/WS2 bilayer in the Zigzag direction is superior to that in the Armchair direction. The results of band structure using the HSE06 method demonstrate that the most stable WS2/WSSe and WSSe/WS2 bilayers are type-II band alignment. WS2/WSSe and WSSe/WS2 bilayers can undergo redox reactions at pH = 0 and pH = 7 respectively. And they all emerge a built-in electric field to cause photo-generated carriers to recombine between the layers to upgrade the photocatalytic performance of the bilayer, which is a typical S-scheme heterojunction. And the power conversion efficiency (PCE) of the WS2/WSSe and WSSe/WS2 bilayers are 15.5 % and 15.7 % respectively, so the utilization rate of sunlight is relatively high. In general, WS2/WSSe and WSSe/WS2 bilayers are ideal materials in the field of photocatalytic water splitting.