Dual‐Ion Directed Synergistic Doping for Regulating Film Crystallization and Carrier Dynamics in High‐Efficiency Antimony Selenosulfide Thin‐Film Solar Cells

Abstract Antimony selenosulfide (Sb 2 (S,Se) 3 ) has attracted significant attention in photovoltaic applications due to its excellent optoelectronic properties. However, despite the recent progress, the efficiency of Sb 2 (S,Se) 3 thin‐film solar cells remains significantly lower than the theoretical limit. Reducing carrier recombination and enhancing crystal orientation‐induced carrier transport is crucial to further improving device performance. In this study, a novel dual‐ion synergistic regulation strategy based on interface passivation layer soaking modification is employed to enhance the crystallization and crystal orientation of Sb 2 (S,Se) 3 thin films. The results demonstrate that soaking and modifying the aluminum oxide (Al 2 O 3 ) interfacial layer with a sodium hydroxide (NaOH) solution effectively reduces the oxygen content on the cadmium sulfide (CdS) surface, thereby suppressing oxygen‐induced [ hk 0] crystal orientation growth in Sb 2 (S,Se) 3 thin films. Moreover, for the first time, this study reveals that the synergistic doping of Na and Al ions regulates the crystallization kinetics of Sb 2 (S,Se) 3 , leading to improve carrier transport, reduce deep‐level defect density, and optimize band structure, ultimately suppressing carrier recombination. As a result, a Sb 2 (S,Se) 3 thin‐film solar cell with an efficiency of 9.79% is achieved under this dual‐ion synergistic regulation strategy.