PEC behaviour of mixed single crystals of tungsten sulphoselenide grown by a CVT technique

Photoelectrochemical (PEC) solar cells have been fabricated with single crystals of WSxSe2−x (0⩽x⩽2) grown by chemical vapour transport (CVT) technique. Energy band location and redox analysis of the material have been done using Mott–Schottky plots. These studies justify the selection of appropriate electrolyte for the PEC work. Various solar cells with single crystals of WSe2, WS0.5Se1.5, WSSe, WS1.5Se0.5 and WS2 as photoelectrodes have been prepared. The solar cell parameters e.g. the fill factor (FF), open circuit voltage (Voc), short circuit current (Isc) and efficiency (η) for all the different cells have been determined. In order to see the effect of increasing the concentration of selenium on the photoresponse, the electrolyte and the intensity of illumination was kept constant and all the samples of WSxSe2−x were prepared from crystals showing absolutely plane faces. The results have been thoroughly described and the implications have been discussed.