Highly Improved Sb_2S_3 Sensitized-Inorganic-Organic Heterojunction Solar Cells and Quantification of Traps by Deep-Level Transient Spectroscopy

摘要

The light-harvesting Sb_2S_3 surface on mesoporous-TiO_2 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 Sb_2S_3 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 Sb_2S_3-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) × 10~(14) cm~3 in Sb_2S_3, 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.