Highly improved Sb₂S₃ sensitized-inorganic-organic heterojunction solar cells and quantification of traps by deep-level transient spectroscopy

The light-harvesting Sb₂S₃ surface on mesoporous-TiO₂ in inorganic-organic heterojunction solar cells is sulfurized with thioacetamide (TA). The photovoltaic performances are compared before and after TA treatment, and the state of the Sb₂S₃ is investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and deep-level transient spectroscopy (DLTS). Although there are no differences in crystallinity and composition, the TA-treated solar cells exhibit significantly enhanced performance compared to pristine Sb₂S₃-sensitized solar cells. From DLTS analysis, the performance enhancement is mainly attributed to the extinction of trap sites, which are present at a density of (2-5) × 10¹⁴ cm^-3 in Sb₂S₃, by TA treatment. Through such a simple treatment, the cell records an overall power conversion efficiency (PCE) of 7.5% through a metal mask under simulated illumination (AM 1.5G, 100 mW cm^-2) with a very high open circuit voltage of 711.0 mV. This PCE is, thus far, the highest reported for fully solid-state chalcogenide-sensitized solar cells. The light-harvesting Sb ₂S₃ surface on mesoporous-TiO₂ in inorganic-organic heterojunction solar cells is sulfurized with thioacetamide. Through such a simple treatment, the cell records an overall power conversion efficiency of 7.5% under simulated illumination (AM 1.5G, 100 mW cm ^-2) and the performance enhancement is mainly attributed to the extinction of trap sites by deep-level transient spectroscopy analysis.