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

Abstract

Antimony selenosulfide (Sb₂(S,Se)₃) has attracted significant attention in photovoltaic applications due to its excellent optoelectronic properties. However, despite the recent progress, the efficiency of Sb₂(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 Sb₂(S,Se)₃ thin films. The results demonstrate that soaking and modifying the aluminum oxide (Al₂O₃) interfacial layer with a sodium hydroxide (NaOH) solution effectively reduces the oxygen content on the cadmium sulfide (CdS) surface, thereby suppressing oxygen-induced [hk0] crystal orientation growth in Sb₂(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 Sb₂(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 Sb₂(S,Se)₃ thin-film solar cell with an efficiency of 9.79% is achieved under this dual-ion synergistic regulation strategy.