Regulating Energy Band Alignment via Alkaline Metal Fluoride Assisted Solution Post‐Treatment Enabling Sb₂(S,Se)₃ Solar Cells with 10.7% Efficiency

Continuously boosting the power conversion efficiency (PCE) and delving deeper into its functionalities are essential problems faced by the very new antimony selenosulfide (Sb 2 (S,Se) 3 ) solar technology. Here, a convenient and effective solution post‐treatment (SPT) technique is used to fabricate high‐performance Sb 2 (S,Se) 3 solar cells, where alkali metal fluorides are applied to improve the quality of Sb 2 (S,Se) 3 films in terms of morphology, crystallinity, and conductivity. In particular, this approach is able to manipulate the S/Se gradient in the films and creates favorable energy alignment which facilitates the carrier transport. As a result, the fill factor and short‐circuit current density of Sb 2 (S,Se) 3 solar cells (Glass/FTO/Zn(O,S)/CdS/Sb 2 (S,Se) 3 /Spiro‐OMeTAD/Au) based on the SPT strategy are significantly enhanced, achieving a champion efficiency of 10.7%. To date, this conversion efficiency value represents the highest efficiency of all Sb‐based solar cells. This study provides an effective post‐treatment strategy for improving the quality of Sb 2 (S,Se) 3 film which sheds new light on the fabrication of high‐efficiency Sb 2 (S,Se) 3 solar cells.