Preparation and photoelectrochemical properties of SnS/SnSe and SnSe/SnS bilayer structures fabricated via electrodeposition

In this work, electrodeposition was employed to deposit a series of thin films, including SnS, SnSe, SnS/SnSe, and SnSe/SnS, onto ITO conductive glass, which were then characterized by XRD, EDS, XPS, SEM, and UV–Vis absorption spectrophotometry. The XRD and SEM results verified the successful preparation of these films, while the EDS and XPS results suggested that the atomic ratio approached 1 for the SnS and SnSe films. According to the UV–Vis absorption spectra, the optical absorption properties were greatly improved for the SnS/SnSe and SnSe/SnS bilayer films compared with those of the monolayer films. For SnS and SnSe, direct band gaps of 1.82 and 1.29 eV and indirect band gaps of 1.03 and 0.89 eV, respectively, were separately obtained from the calculations. The photoelectrochemical properties of the as-fabricated films were further investigated under simulated sunlight, and excellent photoresponses and photostabilities were exhibited by all the samples. The photocurrent densities of SnS, SnSe, SnS/SnSe and SnSe/SnS films were 22, 19, 26, and 20 μA/cm2, respectively.