Preparation and Photoelectrochemistry of Semiconducting WS2 Thin Films

Crystalline 2H-WS2 thin films were prepared by thermal decomposition of amorphous WS3 films sputter-deposited onto a thin Ni layer. Structural, electrical, and photoelectrochemical properties were investigated. Room temperature photoconductivity and photoelectrochemical response were shown to arise from the same interband transitions as in single crystals. The photocurrent spectra measured as a function of wavelength revealed a structure due to excitonic transitions. Surface modification by adsorption of ethylenediaminetetraacetic acid was shown to increase the photocurrent and to reduce the exciton recombination rate. A rectifying solid−liquid junction, having a barrier height of 0.45 V, was formed with the p-WS2 films immersed in the aqueous [Fe(CN)6]3-/4- redox electrolyte.