In-Situ Sulfur Passivation Enabling High Open-Circuit Voltage in Hydrothermally Sb2S3 Solar Cells

Antimony sulfide (Sb 2 S 3 ) has emerged as a promising top cell candidate for tandem solar architectures due to its suitable bandgap, environmentally friendly and earth-abundant composition. However, sulfur volatilization during the preparation process always affects the quality of the thin film and the photovoltaic performance. To address this challenge, we developed a simple in-situ passivation approach applied during Sb 2 S 3 hydrothermal deposition via the strategic supplementation of sulfur source in precursor solutions. This methodology effectively boosts minority charge carrier life time during preparation processing, concurrently enhancing crystalline quality and improving power conversion efficiency (PCE) of the device. Besides reducing the defect of Sb 2 S 3 absorber, we further systematic optimized the electron transport layer (ETL) architecture by using TiO 2 /CdS bilayer to accelerate the charge transfer rate at the interface of Sb 2 S 3 and ETL and to reduce parasitic light absorption. As an overall result, a PCE of 6.83% with a high open-circuit voltage ( V oc ) of 811.5 mV has been achieved, which is the highest V oc for Sb 2 S 3 solar cells to date. This study provides a promising sulfur passivation strategy for the Sb 2 S 3 solar cells by hydrothermal method.