Effect of working pressure on the properties of RF sputtered SnS thin films and photovoltaic performance of SnS-based solar cells

Tin sulfide (SnS) thin films were deposited with a single SnS target by radio frequency magnetron sputtering while varying the working pressure (0.6 Pa to 2.6 Pa), and the structural, chemical, electrical and optical properties of the SnS thin films were investigated. X-ray diffraction results showed that all the SnS thin films had a (111) plane preferred growth orientation, and X-ray photoelectron spectroscopy verified that a SnS thin film was grown with an orthorhombic crystal structure that had, a binding energy of 324.5 eV. Owing to the long wavelength shift in the transmittance spectrum, the optical band gap decreased from 1.56 eV to 1.47 eV. The SnS-based conventionally structured solar cell (Al/ITO/i-ZnO/CdS/SnS/Mo/SLG), which was prepared with a SnS absorption layer and deposited at a working pressure of 2.0 Pa, achieved the highest power conversion efficiency of 0.58%. This result shows its high efficiency compared to those with a conventional structure in other reports.